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US20050166413A1 - CMM arm with exoskeleton 
        - Google Patents

Apparatus for a CMM Arm with Exoskeleton is provided comprising an Internal CMM Arm with a base end and a probe end, and an Exoskeleton driving the Internal CMM Arm through a plurality of transmission. One or more contact probes, optical probes and tools are mounted on the probe end. The CMM Arm with Exoskeleton is provided in manually operable and automated embodiments. The CMM Arm with Exoskeleton is operable for accurate measurement or for performing accurate operations. Methods are provided for operation of the CMM Arm with Exoskeleton.

US20050166413A1 - CMM arm with exoskeleton
- Google Patents

CMM arm with exoskeleton

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Publication number

US20050166413A1

US20050166413A1

US10/988,398

US98839804A

US2005166413A1

US 20050166413 A1

US20050166413 A1

US 20050166413A1

US 98839804 A

US98839804 A

US 98839804A

US 2005166413 A1

US2005166413 A1

US 2005166413A1

Authority

US

United States

Prior art keywords

probe

cmm arm

arm

robot

accordance

Prior art date

2003-04-28

Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)

Granted

Application number

US10/988,398

Other versions

US7395606B2

(
en

Inventor

Stephen Crampton

Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Nikon Metrology NV

Original Assignee

Individual

Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)

2003-04-28

Filing date

2004-11-12

Publication date

2005-08-04

2003-04-28

Priority claimed from GB0309662A

external-priority

patent/GB0309662D0/en

2003-11-26

Priority claimed from GB0327503A

external-priority

patent/GB0327503D0/en

2004-03-10

Priority claimed from GB0405396A

external-priority

patent/GB0405396D0/en

2004-11-12

Priority to US10/988,398

priority

Critical

patent/US7395606B2/en

2004-11-12

Application filed by Individual

filed

Critical

Individual

2005-08-04

Publication of US20050166413A1

publication

Critical

patent/US20050166413A1/en

2008-02-05

Assigned to 3D SCANNERS LIMITED

reassignment

3D SCANNERS LIMITED

ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS).

Assignors: CRAMPTON, STEPHEN JAMES

2008-06-09

Priority to US12/135,621

priority

patent/US7591078B2/en

2008-07-08

Publication of US7395606B2

publication

Critical

patent/US7395606B2/en

2008-07-08

Application granted

granted

Critical

2013-12-12

Assigned to NIKON METROLOGY N.V.

reassignment

NIKON METROLOGY N.V.

ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS).

Assignors: 3D SCANNERS LIMITED

2024-07-18

Adjusted expiration

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Status

Expired - Lifetime

legal-status

Critical

Current

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Classifications

B
—
PERFORMING OPERATIONS; TRANSPORTING

B25
—
HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS

B25J
—
MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES

B25J13/00
—
Controls for manipulators

B25J13/08
—
Controls for manipulators by means of sensing devices, e.g. viewing or touching devices

B
—
PERFORMING OPERATIONS; TRANSPORTING

B25
—
HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS

B25J
—
MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES

B25J13/00
—
Controls for manipulators

B25J13/08
—
Controls for manipulators by means of sensing devices, e.g. viewing or touching devices

B25J13/088
—
Controls for manipulators by means of sensing devices, e.g. viewing or touching devices with position, velocity or acceleration sensors

B
—
PERFORMING OPERATIONS; TRANSPORTING

B25
—
HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS

B25J
—
MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES

B25J9/00
—
Program-controlled manipulators

B25J9/06
—
Program-controlled manipulators characterised by multi-articulated arms

G
—
PHYSICS

G01
—
MEASURING; TESTING

G01B
—
MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

G01B11/00
—
Measuring arrangements characterised by the use of optical techniques

G01B11/02
—
Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness

G01B11/03
—
Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by measuring coordinates of points

G
—
PHYSICS

G01
—
MEASURING; TESTING

G01B
—
MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

G01B5/00
—
Measuring arrangements characterised by the use of mechanical techniques

G01B5/004
—
Measuring arrangements characterised by the use of mechanical techniques for measuring coordinates of points

G
—
PHYSICS

G01
—
MEASURING; TESTING

G01B
—
MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

G01B5/00
—
Measuring arrangements characterised by the use of mechanical techniques

G01B5/004
—
Measuring arrangements characterised by the use of mechanical techniques for measuring coordinates of points

G01B5/008
—
Measuring arrangements characterised by the use of mechanical techniques for measuring coordinates of points using coordinate measuring machines

G
—
PHYSICS

G01
—
MEASURING; TESTING

G01B
—
MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

G01B5/00
—
Measuring arrangements characterised by the use of mechanical techniques

G01B5/08
—
Measuring arrangements characterised by the use of mechanical techniques for measuring diameters

G
—
PHYSICS

G01
—
MEASURING; TESTING

G01B
—
MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

G01B7/00
—
Measuring arrangements characterised by the use of electric or magnetic techniques

G01B7/004
—
Measuring arrangements characterised by the use of electric or magnetic techniques for measuring coordinates of points

G
—
PHYSICS

G01
—
MEASURING; TESTING

G01B
—
MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

G01B7/00
—
Measuring arrangements characterised by the use of electric or magnetic techniques

G01B7/004
—
Measuring arrangements characterised by the use of electric or magnetic techniques for measuring coordinates of points

G01B7/008
—
Measuring arrangements characterised by the use of electric or magnetic techniques for measuring coordinates of points using coordinate measuring machines

G
—
PHYSICS

G05
—
CONTROLLING; REGULATING

G05B
—
CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS

G05B2219/00
—
Program-control systems

G05B2219/30
—
Nc systems

G05B2219/37
—
Measurements

G05B2219/37274
—
Strain gauge

G
—
PHYSICS

G05
—
CONTROLLING; REGULATING

G05B
—
CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS

G05B2219/00
—
Program-control systems

G05B2219/30
—
Nc systems

G05B2219/40
—
Robotics, robotics mapping to robotics vision

G05B2219/40305
—
Exoskeleton, human robot interaction, extenders

Definitions

the present invention

concerns apparatus and method for a CMM Arm with Exoskeleton for performing accurate measurement and operations.

CMMs

are of either the moving bridge or horizontal arm structures; companies including Zeiss (Germany), Hexagon Brown&Sharpe (Sweden) and LK (UK) produce them.

Mechanical touch probes for mounting on conventional CMMs

are supplied by companies including Renishaw (UK).

Optical probes for mounting on conventional CMMs

are supplied by companies including Metris (Belgium).

Automatic probe mounts

such as the Renishaw Autojoint are repeatable to a high degree of accuracy and are supplied with a rack of probes for automatic probe changing.

Rigid structures of static Optical probes

are supplied by Perceptron (USA).

Measuring probes on robot arms taking three-dimensional data from the surface of an object whilst moving at typical speeds of 10 mmsec-200 mm/sec (but can be more or less)

are not accurate.

Companies producing robot arms

include Fanuc (Japan) and Kuka (Germany).

Perceptron and LMI-Diffracto (USA)

offer solutions using robot arms and Optical probes.

3D Scanners and Kuka

showed a solution with real-time optical inspection at the Euromold 2001 exhibition in Frankfurt; its accuracy was of the order of 0.5-1 mm.

Standard industrial robots

thermally grow by around 10 microns per degree Celsius temperature increase per meter of reach; errors in excess of 500 microns can be recorded in production line conditions.

LMI-Diffracto

have an automotive production line installation comprising four standard industrial robots supplied by Kuka, each carrying an Optical probe, wherein the robots are compensated for thermal growth, potentially reducing the thermal error in production line conditions to below 100 microns.

compensation for robot thermal growth

is carried out by measuring a fixed artefact with the Optical Probe.

the Optical probes

measure whilst the robot is static between movements. Error mapping has improved robot accuracy.

There are several approaches

including dancing the robot through a program of planned movements whilst measuring it with a photogrammetric system such as that from Krypton (Holland) or Northern Digital (Canada). The measurements are then used to create an error map.

Error compensation for load

has been carried out by measuring the power used by the servos to automatically calculate the loads on the arm. Even with multiple types of error compensation, accuracies of only 0.2 mm (+/ ⁇ 2 Sigma) have been achieved for robots of the type and reach found in large quantities on automotive production lines. The problem with robot arms carrying scanning probes in which there is relative movement between the probe and the object during scanning is that the systems are not accurate enough to be useful.

Leica Geosystems

supply the 6 degrees of freedom Laser Tracker LTD800. It can measure position and orientation over a 35 m range with a single line of sight at up to 1000 measurements per second. Its accuracy is of the order of 50 microns for slow moving targets. Its cost is in excess of US$130,000. Many of its limitations for robot measuring are similar to those of photogrammetry. The main problems with incorporating laser tracker technology into a robot measuring system is that it is expensive, there are limitations to the orientation of the probe being tracked and the resulting systems are not compact and robust enough to be useful.

Robot Controllers for robot arms

are well understood by those skilled in the field; a standard reference work is ‘Robot Manipulators, Mathematics Programming and Control’ by Richard P Paul. Adept Technologies (US) supply 6-axis robot controllers starting at US$8,500.

US

Adept Technologies

Patent Application GB 2036376A Richter assigned to HA Schlatter AG

(Switzerland) programming is achieved by manually guiding a robot by means of a device mounted on the robot that is held by the user and comprises strain gauges that detect the user's intended direction for robot.

Manual CMM Arms

are expected to become more accurate with further development. These Manual CMM Arms are now accurate enough for many measurement requirements and are a growing sector in the measurement marketplace. They have the flexibility of being able to get into areas with difficult access. Manual CMM Arms are acceptably accurate for many applications, but are not automated; they are expensive to operate, particularly since a semi-skilled operator is required; human operators are also subject to human error.

Manual CMM Arms

are produced by companies including: Cimcore (USA), Faro Technologies (USA), Romer (France), Zett Messtechnik (Germany) and OGP (UK).

Cimcore

USA

Faro Technologies

USA

Romer

France

Zett Messtechnik

Germany

OGP

OGP

U.S. Pat. No. 3,994,798 Eaton

U.S. Pat. No. 5,402,582 Raab assigned to Faro Technologies

U.S. Pat. No. 5,829,148 Eaton

U.S. Pat. No. 6,366,831 Raab assigned to Faro Technologies disclose background information on Manual CMM Arms.

the provision of bearings at the joints of Manual CMM Arms

is well known and U.S. Patent Application 2002/0087233 Raab assigned to Faro Technologies discloses background information on bearings.

Manual CMM arms

are typically limited to around 2 metres in reach from the centre of joint 1 to the probe tip because any longer and it requires two operators to use the arm. The longer the Manual CMM arm is, the less accurate it is. In general, for a modular Manual CMM Arm design all other things being equal, the accuracy is at best inversely proportional to the length.

U.S. Pat. No. 6,366,831 Raab

it is disclosed that in the field, Manual CMM Arms typically have an absolute positional accuracy ten or more times that of a robot arm. Some of the factors in robots that cause inaccuracy including joint misalignments are referred to in U.S. Pat. No. 6,366,831.

Manual CMM arms

such as those manufactured by Faro Technologies and Romer are generally operated by a single person using both hands. Each of the operator's hands provides a different 6 DOF action on the segment of the Manual CMM arm that is gripped by the hand. Some skilled operator's may only need one hand in some applications.

a Manual CMM arm

is a mechanism that is controlled in a closed-loop fashion wherein the operator closes the loop. Such control is a skilled activity; the operator needs to control 6 or 7 axes of arm freedom in a variety of different spatial layouts, under the effect of gravity, with just two hands. It is often the case that the operator mishandles the Manual CMM arm and part or all of the Manual CMM arm accelerates under gravity until there is a collision or the operator steadies it. It is the case that during data capture, the operator applies variable and occasionally excessive forces and torques on the Manual CMM arm, which reduce the accuracy of the measurement data the Manual CMM arm outputs.

a Manual CMM Arm

typically has a compensating device built into the second joint that provides a torque on the upper arm that tends to provide a lifting force on the upper arm to counterbalance it.

Compensating devices for manual CMM arms

are disclosed in U.S. Pat. No. 6,298,569 Raab et al, U.S. Pat. No. 6,253,458 Raab et al, and U.S. Patent Application 2003/0167647 Raab et al, all assigned to Faro Technologies. This means that the arm is lighter for the operator to lift and is consequently less tiring to use.

a pneumatic brake on several axes

is disclosed in PCT/EP01/01570 Nietz assigned to Zett Messtechnik GmbH and offered on Axes 1 to 4 of Zett Mess's AMPG-P manual CMM arm product; the pneumatic brakes can be released by radio remote control switch; the pneumatic brakes act on a disk.

the pneumatic brakes and disks

are mounted directly on the manual CMM arm; they add weight to the manual CMM arm and pass moments through the bearings of the manual CMM arm, thereby reducing its accuracy and usability.

Optical probes on Manual CMM Arms

were disclosed by Crampton, the inventor of the present invention, in several patent applications including WO9705449.

Optical probes for Manual CMM Arms

are provided or are being developed by 3D Scanners, Romer, Faro Technologies, Perceptron, Steinbichler (Germany), Pulstec (Japan) and Kreon (France) amongst others.

Optical probes

are generally mounted offset on the side of the Manual CMM Arm or mounted on the probe end of it.

a measurement accuracy standard

does not exist that defines the way accuracy should be measured for point, line and area Optical probes.

Optical probes

have become accurate, largely because their measuring range is short. In general, Optical probes gather measurement data over a measuring range of the order of 20-400 mm. This is often at a standoff to the end of the Manual CMM Arm. The accuracy of the best Manual CMM Arms combined with the best Optical probes is already better than 0.050 mm (+/ ⁇ 2 Sigma) and can be better than 0.010 mm (+/ ⁇ 2 Sigma) or even 0.002 mm (+/ ⁇ 2 Sigma) for short measuring ranges.

a system

comprising a Manual CMM Arm and an Optical probe

measurements from each

are combined to give the output measurement data.

the measurement accuracy of a system comprising a Manual CMM Arm and an Optical probe

is increased by synchronising the timing of a measurement from the Manual CMM Arm and a measurement from the Optical probe.

the measurement accuracy of a system comprising a Manual CMM Arm and an Optical probe

is increased by time-stamping each measurement from the Manual CMM Arm and time-stamping each measurement from the Optical probe and later using a process of interpolation of the two sets of measurements to provide a combined set of measurements.

the later process of interpolation

can be complex.

a robot

can be calibrated using a reference sphere and a spherically tipped probe on the robot by bringing the spherically tipped probe into contact with the reference sphere a number of times with different robot spatial layouts; a 39-parameter kinematic model for a 6-axis robot embodiment is disclosed.

the alignment of Optical probes to Robots

is disclosed in U.S. Pat. No. 6,321,137B1 De Smet.

a method of manually calibrating a Manual CMM Arm

is disclosed in U.S. Pat. No. 5,402,582 Raab assigned to Faro Technologies. Manual CMM Arms are calibrated by the manufacturer before shipping.

a Manual CMM Arm that is manually calibrated

will perform differently depending on how each operator holds and uses it.

a Manual CMM Arm

is required that is under repeatable patterns of loads and bending moments however it is held for each spatial orientation.

a manual method of calibrating Manual CMM Arms

is required that has the same pattern of loads and bending moments that will occur in its use by different operators.

An automated method of calibrating Manual CMM Arms

is needed to increase the repeatability and accuracy of their calibration, in particular enabling more points to be recorded than is practical or cost effective in current manual processes.

the alignment (also known as calibration or qualification) of Optical probes to Manual CMM Arms

is disclosed in WO9705449 by Crampton, the inventor of the present invention.

the tip of a 6 axis articulated measuring device

is attached to the tip of a robot for the purpose of calibrating the robot.

the tip of a 6 axis articulated measuring device

is attached to the tip of a robot for the purpose of generating an error map.

the tip of a 3 axis articulated measuring device

is attached to the tip of a robot or machine for the purpose of measuring the spatial performance of the robot or machine. Neither of these disclosures is used to measure an object.

a surgical robot and a multiple joint sensor arm

are attached at the base; the multiple joint sensor arm is used manually to make measurements on the patient, a robot program is generated based on those measurements and the robot carries out the surgical intervention.

the measurement

is not automated.

Two items of prior art

disclose devices for measuring the position and or orientation of the endpoint of a robot arm subject to deflections from bending and or thermal expansions.

a simple knee joint with a planar goniometer rigidly attached at both ends

is used to monitor the location of the end of the moving segment. The device is limited to operation in a plane and no out of plane bending is measured.

a device for measuring the position and orientation of the end of a robot arm

comprises a multitude of measuring links joined by rotary and linear bearings and measuring devices to measure rotational angles and linear movements. As well as being pinned at both endpoints of the robot arm, measuring links are rigidly pinned to the robot arm in at least one intermediate hinge joint.

This approach

requires 12 accurate rotary and linear measuring devices on a 6-axis robot. The stack-up of errors from the 12 measuring devices call into question whether it could ever be developed into an accurate 3D measuring device for 6-axis robots.

a robot

is shown with both an optical probe and a tool mounted at the probe end of the robot; the robot can be used alternately for measuring with the optical probe and performing an operation with the tool; however, to achieve measuring accuracy, an optical tracking system is used that has all the disadvantages previously mentioned.

a robot

may be mobile, for example mounted on rails, to provide access around a large object being measured; this further disclosure also has the disadvantages of optical tracking.

a manual marking out system utilising the Faro arm and a robot marking out system utilising an industrial robot from Kuka

are disclosed in PCT/GB01/03865 Gooch; these two systems are either accurate or automated but not both.

Manual CMM Arms

Users demand ever higher accuracy from their Manual CMM Arms.

a significant amount of error in Manual CMM Arms

is derived from the operator over-stressing the Manual CMM Arm, variability of moments on the arm through different hand grip positions and built-in counterbalances providing moments across bearings.

a more accurate calibration process

that is automated to remove human error.

a Manual CMM Arm with an Optical probe

is typically used for many hours at a time. During much of this time, the operator holds the Manual CMM Arm at a distance from him, often in awkward locations. The weight that is supported at a distance can be several kilograms for a long Manual CMM Arm. This is hard work and is tiring for many operators, particularly smaller people; operator fatigue is a common problem and this can lead to illness, incapacitation or injury. Much of the work done with Manual CMM Arms is for unique components that only need to be optically inspected once. Often, the surface being inspected is not immediately accessible and requires temporary gantries to be erected for the operator to climb on so that the arm can be manipulated.

articulated arm CMMs

comprising a series of preferably 6 or 7 joints separated by rigid segments are more flexible than orthogonal axis configuration CMMs.

automated orthogonal axis configuration CMMs

are several orders more accurate than automated articulated Robot arms.

automated orthogonal axis configuration CMMs

are less suitable than automated articulated arm Robots for locating in a manufacturing environment such as on an assembly line. The problem is that no automated CMM machine is available that is articulated and sufficiently accurate.

Manual CMM Arms

are becoming more accurate and less robust.

the existing designs of Manual CMM Arms

have the precision measuring system exposed to shocks, moments and abuse in usage and transportation.

Existing designs of transportation case

are unsophisticated and expose Manual CMM Arms to damage, particularly from shock.

Flemming

discloses a robot arm with attached measuring arm that is only usable within a plane and does not take into account out of plane bending.

Slocum

discloses a measurement device for a robot arm for operation within 3D space. It requires 12 rotary and linear measuring devices for a 6-axis robot, it is complex, expensive to manufacture and limited in accuracy due to error stack-up.

Another objective

is to provide a CMM Arm with Exoskeleton that can collect data.

Still another objective

is to provide a CMM Arm with Exoskeleton that can perform operations.

a portable Robot CMM Arm

comprises an automated Exoskeleton that supports and manipulates an Internal CMM Arm via transmission means such that it can carry out measurement of an object.

the Robot CMM Arm and the Internal CMM Arm

are rigidly attached at the base.

the Exoskeleton and the Internal CMM Arm

have the same number of axes and approximately the same joint axis orientations and joint centres.

the Robot CMM Arm

has preferably 6 or 7 axes.

There are transmission means between the Exoskeleton and the Internal CMM Arm

such that the Exoskeleton both drives and supports the Internal CMM Arm.

the transmission means

are non-rigid and the probe end of the Internal CMM Arm can move small amounts relative to the probe end of the Exoskeleton.

This first embodiment

fundamentally differs from the devices of Slocum and Flemming that require rigid attachment between the probe end of the robot arm and the probe end of the measuring device.

At least one probe

is mounted on the probe end of the Internal CMM Arm. Positions from the Internal CMM Arm and measurements from the Probe are combined and a novel systematically changing synchronisation label and method are proposed to avoid inaccuracy from ambiguity in the combination.

a control box

is integrated into the base of the Robot CMM Arm. Slip-rings enable infinite rotation on axial axes.

the Robot CMM Arm

typically weighs 20-30 kg and is portable, enabling it to be brought to the object being measured. It is a further purpose of this first embodiment to provide a method for positioning the Robot CMM Arm to measure data of an object.

This Robot CMM Arm invention

has a novel structure, and novel capabilities that none of Robots, Manual CMM Arms or Conventional CMMs are capable of.

an Industrial Robot CMM Arm

comprises an Exoskeleton that encloses an Internal CMM Arm.

a tool

can be mounted on the Industrial Robot CMM Arm for performing operations such as milling.

the Exoskeleton and the Internal CMM Arm

are rigidly attached at the probe end such that the Internal CMM Arm can measure the position of the tool and guide it more accurately through space than in any previous robot.

an Actively Supported Robot CMM Arm

comprises active transmission means that support and move the Internal CMM Arm from the Exoskeleton for the purpose of precise measurement.

the Exoskeleton

cradles the Internal CMM Arm to unweight it and significantly reduce the forces and moments on it.

the transmission means

are non-rigid and the probe end of the Internal CMM Arm can move small amounts relative to the probe end of the Exoskeleton. This means that the Actively Supported Robot CMM Arm is more accurate than other types of Robot CMM Arm.

air bearings

are provided between the Internal CMM Arm and the Exoskeleton.

a quantity-measuring probe

is attached to the probe end of the Robot CMM Arm. Means are provided for combining the quantities measured with the CAD model of the object being measured.

a method and apparatus for a Mobile Robot CMM Arm

is disclosed.

a Robot CMM Arm

is mounted on a tripod with retractable feet built into an electric vehicle and moved from one measuring position to the next. It is typically used for automatically scanning large objects such as vehicles or aircraft and provides a lower cost and more flexible alternative to the large horizontal or bridge type CMMs currently used.

a Robot CMM Arm with displaceable exoskeleton embodiment

is disclosed.

the Internal CMM Arm

is displaced from the Exoskeleton and manually used for generating a robot program.

the Internal CMM Arm

is replaced in the Exoskeleton and the robot then executes the robot program automatically.

Manual manipulation of the Internal CMM Arm for generating a robot program

has the advantage of being faster and more usable than conventional methods such as using a teach pendant.

a Robot CMM Arm

comprising a coupled CMM Arm and Robot is disclosed.

the CMM Arm

is supported by the Robot in at least two positions: at the probe end and at an intermediate position.

This embodiment

has the advantage of moving the sources of heat from the vicinity of the CMM Arm.

a Manual CMM Arm with Exoskeleton

is disclosed.

the Internal CMM Arm

is supported and driven by an Exoskeleton that is in turn supported and moved by an operator.

Current Manual CMM Arms

combine the functions of measurement, self-support and robustness for operator handling in the same arm.

This eighth embodiment

places the function of measurement into an Internal CMM Arm and the functions of support and robustness for operator handling into the Exoskeleton.

the Internal CMM Arm

is always supported in exactly the same way at each spatial position such that the loads on the Internal CMM Arm are repeatable and are the same as the loads during the calibration process.

This load pattern repeatability

means that the Manual CMM Arm with Exoskeleton is a device that is more accurate than any existing Manual CMM Arm device.

Flexible button means

are provided for the operator to attach a button unit with wireless transmitter at whatever location is convenient on the exoskeleton; a wireless receiver is integrated into the system.

Bump stop means

are provided in the exoskeleton to cushion the Internal CMM Arm from undesirable shocks and loads.

Probe covers

are provided to protect the probe from knocks and to compensate some of the load on a contact probe.

Measuring methods

are provided for the use of the Manual CMM Arm with Exoskeleton and a number of different contact and non-contact probes.

An automated calibration apparatus and method for a Manual CMM Arm with Exoskeleton

is disclosed.

a transportation case with load spreading mechanism

is provided to minimise the magnitude of the shock loads on the Manual CMM Arm with Exoskeleton during transportation.

a Manual CMM Arm with Holding Exoskeleton

is disclosed.

One or more joints in the Exoskeleton

may be locked by means of a brake. This means that an operator who needs to pause in mid-operation, can lock the arm in whatever position it is in, removing the need to return it to its rest position. Previous braking systems have acted through and placed load on the CMM Arm, but this embodiment has the advantage of acting on the Exoskeleton without placing any loads on the Internal CMM Arm.

a Manual CMM Arm with Endoskeleton embodiment of the present invention

is disclosed.

the CMM arm

is external to the supporting endoskeleton.

the function of counterbalancing

has either been parallel and external to the arm as in the Romer and Cimcore devices or embedded in the arm such that the bending moment is across the arm.

This invention

both hides the function of compensation inside the CMM Arm and compensates without applying a bending moment across the arm.

a Robot CMM Arm with Endoskeleton

is disclosed.

the CMM arm

is external to the supporting and driving robot endoskeleton.

the first advantage

is that the External CMM Arm hides all the drives, providing an arm suitable for applications with limited access.

the second advantage

is that the External CMM Arm has greater section and bends less, rendering it more accurate.

FIG. 1A

is a schematic diagram for a 6-axis Robot CMM Arm in accordance with a first embodiment of the present invention

FIG. 1B

is a schematic diagram for a 7-axis Robot CMM

FIG. 1C

is a layout for a Robot CMM Arm system

FIG. 2

is a schematic diagram of the Joints and Segments of the Exoskeleton and the Internal CMM Arm;

FIG. 3

is a schematic diagram of the reach of a Robot CMM Arm

FIG. 4

is a schematic diagram of the virtual reach of a Robot CMM Arm with an Optical probe

FIG. 5A

is a schematic diagram of a long CMM Segment

FIG. 5B

is a schematic diagram of a short CMM Segment

FIG. 5C 1

is a schematic diagram of CMM Segment 8 ;

FIG. 5C 2

is a schematic diagram of cantilever and in-line orthogonal joint options

FIG. 5D

is a schematic diagram of the base

FIG. 5E

is a layout of separate base segments that are separately mounted

FIG. 5F

is a layout of separate base segments that are mounted on the same surface

FIG. 5G

is a layout of the Exoskeleton base mounted on a surface

FIG. 5H

is a layout of a common base

FIG. 6

is a schematic diagram of a stand

FIG. 7A

is a layout of a Robot CMM Arm mounted on a vibration-isolated table

FIG. 7B

is a layout of a floor mounted Robot CMM Arm

FIG. 7C

is a layout of a Robot CMM Arm mounted on a surface plate embedded in the floor;

FIG. 7D

is a layout of Robot CMM Arms mounted on linear rails

FIG. 7E

is a layout of two independent Robot CMM Arms mounted on a horizontal rail

FIG. 7F

is a layout of a Robot CMM Arm mounted on a vertical axis that traverses horizontally;

FIG. 7G

is a layout of two Robot CMM Arms mounted on a moving multiple arm base

FIG. 7H

is a layout of a Robot CMM Arm mounted on an object

FIG. 7I

is a plan view of a Robot CMM Arm mounted adjacent to a processing machine

FIG. 7J

is a layout of a Robot CMM Arm mounted between several processing machines

FIG. 7K

is a layout of a Robot CMM Arm mounted between several work areas

FIG. 7L

is a layout of a Robot CMM Arm on a bridge over the object

FIG. 7M

is a layout of a Robot CMM Arm adjacent to an object mounted on a rotary table

FIG. 7N

is a layout of a Robot CMM Arm adjacent to an object mounted on a linear table

FIG. 8A

is a layout of a Robot CMM Arm mounted on a wall

FIG. 8B

is a layout of a Robot CMM Arm mounted on a gantry

FIG. 8C

is a layout of a Robot CMM Arm mounted on an inclined platform

FIG. 8D

is a layout of a Robot CMM Arm mounted on a horizontal arm CMM;

FIG. 8E

is a layout of a Robot CMM Arm mounted on a moving bridge CMM

FIG. 8F

is a layout of a Robot CMM Arm mounted on a rotating wedge

FIG. 9

is a layout of a Robot CMM Arm with a photogrammetric tracker

FIG. 10

is a detailed layout for a Robotic CMM Arm system

FIG. 11A

is a diagram of the architecture of a Robotic CMM Arm

FIG. 11B

is a diagram of an alternative architecture of a Robotic CMM Arm

FIG. 12A

is a schematic diagram of an encoder

FIG. 12B

is a schematic diagram of a Dual pattern encoder

FIG. 12C

is a schematic diagram of a Dual pattern encoder mapping apparatus

FIG. 12D

is a schematic diagram of axis and pattern centres

FIG. 13A

is a schematic diagram of forced air circulation

FIG. 13B

is a schematic diagram of high inertia and low inertia Robot CMM Arms

FIG. 14

is a schematic diagram of the location of all the transmission means

FIG. 15

is a schematic diagram of the location of the Segment 8 transmission means

FIG. 16

is a schematic diagram of rotation restraining means

FIG. 17

is two sections of radial transmission means

FIG. 18

is two sections of torsional transmission means

FIG. 19

is a schematic of a compensating device

FIG. 20

is a schematic diagram of hard limits and limit switches in an axial joint

FIGS. 21A and 21B

are schematic diagrams of hard limits in an orthogonal joint

FIG. 21C

is a schematic comparison of the axis separations for a Robot CMM Arm and a Manual CMM Arm;

FIG. 22

is a schematic diagram of bearings

FIG. 23

is a view and a section of the probe end of the Internal CMM Arm

FIG. 24

is a longitudinal section of a touch trigger probe mounted on the probe end

FIG. 25

is a longitudinal section of an optical probe mounted on the probe end

FIG. 26

is a view of the optical probe and bracket

FIG. 27A

is a diagram of the architecture of the probe

FIG. 27B

is a schematic diagram of a probe connected to three cables and a probe box

FIG. 27C

is a layout of a probe with one cable to a probe box running exterior to the Robot CMM Arm;

FIG. 27D

is a layout of a probe with a probe box connected through the Robot CMM Arm;

FIG. 28

is a two view schematic diagram of the principle of a stripe probe

FIG. 29

is a schematic diagram of a stripe probe scanning

FIG. 30

is a schematic diagram of the measuring areas of a stripe

FIG. 31

is a schematic diagram of a patch of stripes

FIG. 32

is a schematic diagram of a number of overlapping patches

FIG. 33A

is a schematic diagram of a two-view stripe probe

FIG. 33B

is a schematic diagram of a two-view stripe probe scanning a stepped object

FIG. 34A

is a schematic diagram of a two-stripe probe

FIG. 34B

is a schematic diagram of a two-stripe probe scanning the vertical wall of a stepped object

FIG. 35

is a schematic diagram of a platform for a laptop

FIG. 36

is a schematic diagram of a pendant

FIG. 37

is a schematic diagram of a headset on an operator

FIG. 38A

is a layout of buttons on a Robot CMM Arm

FIG. 38B

is a layout of footswitches

FIG. 38C

is a layout of a remote control with strap

FIG. 39

is a layout of coordinate systems

FIG. 40

is a diagram of the architecture of the Control PCB

FIG. 41A

is a diagram of the architecture of the Joint PCB

FIG. 41B

is a diagram of the position averaging in the Joint PCB

FIG. 41C

is a timing diagram of the encoder counts and trigger pulse

FIG. 41D

is a flow diagram of a position averaging process

FIG. 41E

is a diagram of a strain gauge system

FIG. 42

is a flow diagram for a synchronisation process with the Probe as Master

FIGS. 43A, 43B and 43 C

are timing diagrams for probe measurement

FIG. 44

is a timing diagram showing the delay of a triggered probe measurement

FIG. 45

is a flow diagram for a synchronisation process with the Probe as Slave;

FIG. 46

is a flow diagram for a time stamping measurement process

FIG. 47

is a schematic diagram of a probe scanning a ridged artefact

FIG. 48

is a diagram of +X and ⁇ X scans of the ridged artefact

FIG. 49

is a layout of calibration equipment

FIG. 50

is a diagram of a calibration artefact

FIG. 51A

is a location diagram for positioning the calibration artefact

FIG. 51B

is a layout of calibration equipment with a rotary axis

FIG. 52

is a flow diagram of a measuring process

FIG. 53

is a schematic diagram for an Industrial Robot CMM Arm in accordance with a second embodiment of the present invention.

FIG. 54

is a diagram of a hybrid 6/7-axis Industrial Robot CMM Arm

FIG. 55

is a schematic of a global coordinate system artefact in a multiple Robot CMM Arm cell

FIG. 56

is a flow diagram of a feature inspection process

FIG. 57

is a flow diagram of a surface inspection process

FIG. 58

is a flow diagram of a tool operation process

FIG. 59A

is a flow diagram of an inspection and tool adjustment process

FIG. 59B

is a flow diagram of a component adjustment process

FIG. 60

is a schematic diagram of an Actively Supported Robot CMM Arm in accordance with a third embodiment of the present invention.

FIG. 61

is a diagram of a radial Active Transmission Means with Active Axial Support

FIG. 62

is a schematic diagram of a torsional Active Transmission Means with Active Axial and Radial Support

FIG. 63

is a diagram of an Active Transmission Means with Active Radial Support

FIG. 64

is a schematic diagram of an Active Support Control System

FIG. 65

is a schematic diagram of a Control loop with Active Support

FIG. 66

is a flow diagram of a Quantity Measurement process in accordance with a fourth embodiment of the present invention.

FIG. 67

is a flow diagram of a Quantity Modelling process

FIG. 68

is a flow diagram of a Quantity Analysis, Visualisation and Feedback process

FIG. 69

is a diagram of a Mobile Robot CMM Arm in accordance with a fifth embodiment of the present invention.

FIG. 70

is a floor plan of a Mobile Robot CMM Arm installation

FIG. 71

is a diagram of reference cone installations

FIG. 72

is a data structure for reference cone positions, target positions and tape positions

FIG. 73

is a flow diagram of a Mobile Robot CMM Arm preparation process

FIG. 74

is a flow diagram of a Mobile Robot CMM Arm measuring process

FIG. 75

is a diagram of a Robot CMM Arm with displaceable exoskeleton in accordance with a sixth embodiment of the present invention.

FIG. 76

is a diagram of a slotted tubular Robot Segment

FIG. 77

is a diagram of a split bearing Transmission Means

FIG. 78

is a flow diagram of a Robot CMM Arm with displaceable exoskeleton measuring process

FIG. 79

is a schematic of a coupled Robot CMM Arm

FIG. 80A

is a layout for a Manual CMM Arm with Exoskeleton System

FIG. 80B

is a schematic of the Manual CMM Arm with Exoskeleton at rest

FIG. 81

is a schematic of a Probe Cover

FIG. 82A

is a schematic of an Optical Probe Cover

FIG. 82B

is a schematic of an Optical Probe Cover as a handle

FIG. 83A

is a schematic of a Partial Exoskeleton

FIG. 83B

is a schematic of an Extended Partial Exoskeleton

FIG. 83C

is a schematic of a Protective Extended Partial Exoskeleton with different Internal CMM and Exoskeleton joint positions

FIG. 83D

is a flow diagram of a manual contact measuring process

FIG. 83E

is a flow diagram of an automatic contact measuring process

FIG. 83F

is a flow diagram of a non-contact scanning process

FIG. 83G

is a flow diagram of a contact scanning process

FIG. 83H

is a schematic of a modular robotic calibration rig

FIG. 83I

is a schematic of an external robot calibration rig

FIG. 84

is a schematic of a Transportation case

FIG. 85

is a layout for a Manual CMM Arm with Exoskeleton System

FIG. 86A

is a diagram of an unsupported Manual CMM Arm showing forces

FIG. 86B

is a diagram of a Manual CMM Arm with Exoskeleton showing forces

FIG. 86C

is a diagram of a Manual CMM Arm with Endoskeleton showing forces

FIG. 87

is a schematic diagram of the Joints and Segments of the Robot Endoskeleton and the External CMM Arm;

FIG. 88

is a schematic of the Arm network

FIG. 89A

is a schematic of the Probe End Module interfaces

FIG. 89B

is a diagram of the Probe End Module exoskeleton support

FIG. 89C

is a diagram of the Probe End Module mounting

FIG. 90A

is a diagram of the 1-axis Probe End Module

FIG. 90B

is a section of the hybrid 0/1-axis Probe End Module.

the first embodiment of this CMM Arm with Exoskeleton invention

is a Portable Robot CMM Arm.

This Portable Robot CMM Arm embodiment

comprises an Internal CMM Arm guided by an Exoskeleton.

the Exoskeleton

supports and manipulates the Internal CMM Arm via transmission means such that it can measure accurately.

This invention

can be embodied in many Robot CMM Arm articulated arm layouts. There are two preferable layouts for a Robot CMM Arm in accordance with a first embodiment of the present invention: 6-axis with 6 joints and 7-axis with 7 joints.

FIGS. 1A and 1B

are diagrams showing the preferable 6-axis and 7-axis layouts respectively for a Robot CMM Arm 1 in accordance with a first embodiment of the present invention.

An articulated Robot CMM Arm 1

has a base end 2 and a probe end 3 and comprises a series of segments and rotating joints between the two ends.

An axial joint

(labelled ‘A’ in FIGS. 1A, 1B ) rotates about the common axis of its two adjoining segments.

An orthogonal joint

(labelled ‘O’ in FIGS. 1A and 1B ) rotates as a hinge between its two adjoining segments.

the type of joints in order from the base end 2 to the probe end 3

is AOOAOA referring respectively to joint centres 21 , 22 , 24 , 25 , 26 and 27 .

the type of joints in order from the base end 2 to the probe end 3

is AOAOAOA referring respectively to joint centres 21 , 22 , 23 , 24 , 25 , 26 and 27 .

the 6-axis layout

has the advantage of lower cost.

the 7-axis layout

has the advantage of increased flexibility for access to complex objects.

the preferable 7-axis Robot CMM Arm 1 layout of FIG. 1B

is described in this first embodiment of the Robot CMM Arm 1 invention, but the invention is not limited to this joint layout or the preferable 6-axis layout of FIG. 1A and can have more or less joints than 7. For a simple application, 3 joints can be sufficient.

This invention

is not limited to only rotational axes of movement. As will be disclosed later, it can comprise one or more linear axes of movement to which the base end 2 is preferably attached.

FIG. 1 c

shows the Robot CMM Arm system 150 comprising a Robot CMM Arm 1 , connected to a laptop 151 with a cable 152 .

the Robot CMM Arm 1

has a base end 2 and a probe end 3 . It is mounted on a surface 7 .

a probe 90

is mounted on the probe end 3 of the Robot CMM Arm 1 .

An Optical probe 91

is also mounted towards the probe end 3 of the Robot CMM Arm 1 .

the Robot CMM Arm 1

comprises a base 4 , an Internal CMM Arm 5 , an Exoskeleton 6 and Transmission Means 10 .

the object 9 being measured

is situated on the surface 7 .

FIG. 2

shows the two main parts of the Robot CMM Arm 1 : the Internal CMM Arm 5 and the Exoskeleton 6 sharing a common base 4 and common joint centres 21 , 22 , 23 , 24 , 25 , 26 and 27 .

the Internal CMM Arm 5

comprises segments 32 , 33 , 34 , 35 , 36 , 37 and 38 referred to in the text as CMM Segment 2 - 8 respectively.

CMM Segment 8 38

reaches to the probe end 3 of the Robot CMM Arm 1 .

the common base 4

is also referred to as CMM Segment 1 31 .

the Internal CMM Arm 5

further comprises joints 51 , 52 , 53 , 54 , 55 , 56 , 57 referred to in the text as CMM Joint 1 - 7 respectively.

the Exoskeleton 6

comprises segments 42 , 43 , 44 , 45 , 46 , 47 and 48 referred to in the text as Exoskeleton Segment 2 - 8 respectively.

Exoskeleton Segment 8 48

does not reach to the probe end 3 of the Robot CMM Arm 1 .

the common base 4

is also referred to as Exoskeleton Segment 1 41 .

the Exoskeleton 6

further comprises joints 61 , 62 , 63 , 64 , 65 , 66 and 67 referred to in the text as Exoskeleton Joint 1 - 7 respectively.

the Robot CMM Arm 1

further comprises Transmission Means 72 , 73 , 74 , 75 , 76 , 77 and 78 referred to in the text as Transmission Means 2 - 8 respectively, attaching Internal CMM Arm 5 to Exoskeleton 6 .

Transmission Means 2 72

attaches CMM Segment 2 32 to Exoskeleton Segment 2 42 .

Transmission Means 3 73

attaches CMM Segment 3 33 to Exoskeleton Segment 3 43 and so on correspondingly for Transmission Means 4 - 8 74 , 75 , 76 , 77 and 78 .

the Reach 80 of the Robot CMM Arm 1

is defined as being from Joint Centre 2 22 to the probe end 3 of CMM Segment 8 38 , when the CMM Joints 3 - 7 are rotated to maximise this distance.

the bulk of the Reach 80 of the Robot CMM Arm 1

comprises the sum of the lengths of CMM Segment 3 33 and CMM Segment 5 35 .

the reach 80

is increased with a virtual reach 81 of the distance between the probe end 3 of CMM Segment 8 38 and the Optical measuring mid-point 82 of the measuring depth over which measurements can be taken.

Each CMM Segment

has a high stiffness. Any loads on the Internal CMM Arm 5 resulting in bending or torsion in a segment will reduce the accuracy of the Internal CMM Arm 5 .

Gravity

is a continuous source of load and the effect of gravity is different for different spatial orientations of the Robot CMM Arm 1 .

a typical maximum angular torsional slope in a long CMM segment of the Robot CMM Arm in normal use

is 0.25 arc-second, but could be more or less, particularly depending on the length of the CMM Segment.

a typical maximum angular bending slope in a long CMM Segment of the Robot CMM Arm in normal use

is 0.5 arc second, but could be more or less, particularly depending on the material, length and diameter of the long CMM Segment.

Each CMM Segment

comprises one or more significant items: Segment Item Joints Description CMM Segment 1 Base 1 Machined aircraft aluminium CMM Segment 2 Shoulder 1, 2 Machined aircraft aluminium CMM Segment 3 Housing 2 Machined aircraft aluminium Link 0 Woven carbon fibre Housing 3 Machined aircraft aluminium CMM Segment 4 Elbow 3, 4 Machined aircraft aluminium CMM Segment 5 Housing 4 Machined aircraft aluminium Link 0 Woven carbon fibre Housing 5 Machined aircraft aluminium CMM Segment 6 Hand 5, 6 Machined aircraft aluminium CMM Segment 7 Wrist 6, 7 Machined aircraft aluminium CMM Segment 8 Probe 7 Machined aircraft aluminium

CMM Segments 3 , 5 33 , 35

comprise a Link Member 102 with diameter 108 and wall thickness 109 between two End Housings 100 , 101 housing one joint each.

CMM Segments 2 , 4 , 6 and 7 32 , 34 , 36 and 37

comprise a Double Housing 103 housing two joints, one at each end.

CMM Segment 8 38

comprises a Probe End Housing 105 housing CMM Joint 7 57 at one end with CMM Probe Mounting Means 39 at the other end to which a Probe 90 is attached ending in Probe end 3 .

CMM Joints 2 , 4 , 6 52 , 54 , 56

there are different options for providing an orthogonal joint for CMM Joints 2 , 4 , 6 52 , 54 , 56 .

FIG. 5C 2

a cantilever option and an in-line option are shown for CMM Joint 2 52 .

the preferred option for CMM Joints 2 , 4 , 6 52 , 54 , 56

is in-line.

the scope of the Robot CMM Arm 1

is not limited to either of these joint options but could include any other design of orthogonal joint.

Each Exoskeleton Segment

comprises one or more significant items: Segment Item Joints Description Exoskeleton Segment 1 Base 1 Machined aircraft aluminium Exoskeleton Segment 2 Shoulder 1, 2 Machined aircraft aluminium Exoskeleton Segment 3 Housing 2 Machined aircraft aluminium Link 0 Aluminium tube Housing 3 Machined aircraft aluminium Exoskeleton Segment 4 Elbow 3, 4 Machined aircraft aluminium Exoskeleton Segment 5 Housing 4 Machined aircraft aluminium Link 0 Aluminium tube Housing 5 Machined aircraft aluminium Exoskeleton Segment 6 Hand 5, 6 Machined aircraft aluminium Exoskeleton Segment 7 Wrist 6, 7 Machined aircraft aluminium CMM Segment 8 Probe 7 Machined aircraft aluminium Base Layout

the Base 4

comprises CMM Segment 1 31 housing CMM Joint 1 51 with Joint Centre 21 screwed into Mounting Plate 8 by means of a standard 3.5′′ heavy duty thread 116 and Exoskeleton Segment 1 41 housing Exoskeleton Joint 1 61 with Joint Centre 21 rigidly attached to CMM Segment 1 31 with bolts 106 .

the Mounting Plate 8

is attached to the Surface 7 by Mounting means 104 such as Mounting Bolts 107 .

Both the Internal CMM Arm 5 and the Exoskeleton 6

have base segments 31 , 41 respectively.

Exoskeleton Segment 1 41

is rigidly attached to CMM Segment 1 31 with counter-bored bolts 106 .

CMM Segment 1 31

can be mounted to a first surface 7 a and Exoskeleton Segment 1 41 can be mounted to a second surface 7 b in such a way that CMM Segment 1 31 is not attached to Exoskeleton Segment 1 41 .

both the CMM Segment 1 31 and the Exoskeleton Segment 1 41

can be independently mounted to the same Surface 7 .

CMM Joint 1 51

can be raised higher above the surface 7 by providing a base extension section between the surface 7 and the base 2 .

Such a base extension section

is preferably based on a lightweight tube made of woven carbon fibre with a low Coefficient of Thermal Expansion typically 0.075 ppm/degC. This means that the measurement of the Robot CMM Arm 1 with a base extension tube relative to the surface 7 will not be significantly affected by changes in temperature.

CMM Segment 1 31

can be attached, rigidly or flexibly to Exoskeleton Segment 1 41 which is mounted on a surface 7 .

CMM Segment 1 31 and Exoskeleton Segment 1 41

can be the same base item 4 mounted on surface 7 to which both CMM Segment 2 32 and Exoskeleton Segment 2 42 are attached via CMM Joint 1 51 and Exoskeleton Joint 1 61 respectively. It is a purpose of this Robot CMM Arm invention that there can be any form of base mounting.

This Robot CMM Arm 1 invention

is provided in this first embodiment as a range of portable Robot CMM Arms with different reaches.

the portable Robot CMM Arm Reach 80

varies from 0.6 m to 3 m.

the scope of this invention

is not limited to reaches within this range and the Reach 80 could be less than 0.6 m or more than 3 m.

a typical weight for the moving parts of a medium reach Internal CMM arm 5

is 2.5-4 kg.

the Exoskeleton 6

supports and drives the Internal CMM Arm 5 so as to minimise stresses on the Internal CMM Arm 5 and in particular on the Internal CMM Arm Joints 51 - 57 .

the only loads on the Exoskeleton 6

should be gravity and the loads transferred through the Transmission Means 10 .

the Exoskeleton 6

always supports the Internal CMM Arm 5 in the same places, providing repeatable loadings at the same spatial orientation.

a state of the art Manual CMM Arm

is designed for additional stresses applied to it by the operator, which are significantly higher than those on the Internal CMM Arm 5 and are also applied at different loading locations and directions depending on where and how the operator grips it. This means that an Internal CMM Arm 5 does not need as high stiffness as a Manual CMM Arm of similar reach and is lighter than it.

the Internal CMM Arm 5

has two long Link Members 102 in the upper arm and lower arm: CMM Segment 3 33 , CMM Segment 5 35 .

the Link Member diameter 108 of the Internal CMM Arm 5

is in the range 40 mm-70 mm.

the scope of this Robot CMM Arm 1 invention

is not constrained to this Link Member diameter; Link Member diameters more than 70 mm or less than 40 mm can be used.

a state of the art Manual CMM arm

During handling by an operator, the forces and torques on a state of the art Manual CMM arm come from, amongst others: gravity which is related to the combination of joint angles at that instant in time, the compensating device, the accelerations, and the operator induced forces and torques. The operator can apply bending forces on either link. For this reason, a Manual CMM arm typically has the same link diameter for both segments.

the Exoskeleton 6

supports all segments 32 - 38 of the Internal CMM Arm 5 approximately equally. For this reason, the Internal CMM Arm 5 of this first embodiment has the same Link Member diameter 108 for both segments 33 and 35 .

the scope of this Robot CMM Arm invention

is not constrained to a uniform Link Member diameter and Link Member diameters can be different.

the Link member 102

is essentially a simple beam supported at either end by joints or transmission means.

the main mode of deflection

is under the gravitational force when horizontal. Assuming there are no undesirable moments on the link member 102 , then the deflection of the Link member 102 is largely independent of the Link Member thickness 109 . It follows that the Link member thickness can be very small and this is consistent with the objective of minimum mass for the Internal CMM Arm 5 .

the Link Member thickness 109 of the Internal CMM Arm

is preferably 1 mm to 1.5 mm for both segments 33 and 35 . For longer reach arms, Link Member thickness 109 and/or the Link Member diameter 108 are typically increased to maintain stiffness.

the Link Member diameters and thicknesses

are parameters that are optimised in the design process for different design specifications and manufacturing constraints.

the Exoskeleton Segments 2 - 8 42 - 48

pass down over the Internal CMM Arm segments during assembly.

the shape of the CMMSegments 32 - 38 of the Internal CMM Arm

is constrained to have as small a maximum radial dimension as possible. Any reduction in maximum radial dimension enables the Exoskeleton Segments 2 - 8 42 - 48 to be reduced in size and this makes the Robot CMM Arm invention smaller and more flexible in its application.

the Robot CMM Arm 1

is portable and that the weight be minimised. This object is not compatible with requirements of minimising cycle times and the correspondingly high angular accelerations at the joints. Performance in terms of maximum angular velocities and accelerations are higher for a short reach Robot CMM Arm 1 than for a long reach Robot CMM Arm 1 . Maximum joint angular velocities are typically in the range 20 deg/sec to 400 deg/sec. ExoskeletonJoints 1 - 4 61 - 64 have lower maximum angular velocities than ExoskeletonJoints 5 - 7 65 - 67 because the Torques are higher.

Joint 2

can typically have a maximum angular velocity of 20 deg/sec.

Joint 7

can have a maximum angular velocity of 400 deg/sec.

the scope of this Robot CMM Arm invention

is not constrained to this range of maximum angular velocities and the maximum angular velocity of a joint can be higher than 400 deg/sec or lower than 20 deg/sec.

the Exoskeleton structure

is less stiff than the Internal CMM Arm since high stiffness is not required for the functions of support and drive.

the Exoskeleton structure

is therefore light, making the Robot CMM Arm more portable.

Typical masses for a range of portable Robot CMM Arms

vary from 18 kg for a Im Reach to 35 kg for a 3 m Reach.

the scope of this Robot CMM Arm invention

is not constrained to this range of masses and the maximum mass can be higher than 35 kg or lower than 18 kg.

the Exoskeleton structure

is compact and lies close to the Internal CMM arm. This means that the Robot CMM Arm can access difficult areas for measurement such as car interiors. The Robot CMM Arm can thus be applied to applications that cannot be tackled without extensive preparation of the object such as when a car seat cannot be measured in situ but must be first removed from the car.

the Exoskeleton Segments 42 - 48

form a sealed shape to protect the Internal CMM Arm Segments 32 - 38 from exposure to damaging solids, liquids or gases during use.

the Exoskeleton Segments 42 - 48

are hollow to fit over the Internal CMM Arm Segments 32 - 38 .

the Exoskeleton shape

also serves the functions of making the Robot CMM Arm manually usable and protects parts of the Internal CMM Arm in the event of a collision. Parts of the Exoskeleton structure have non-functional surface shape for reasons of aesthetics.

One of the largest factors determining the Exoskeleton shape

is the size and location of the motor and gearbox drive elements.

the Housings 100 , 101 , 103 , 105

are made of aircraft aluminium; the aluminium is anodised.

the Link members 102

comprise a thin-walled tube made of a woven carbon fibre-epoxy composite material such as Toray T 700 that provides a near-zero coefficient of thermal expansion, high stiffness and low density. Link members 102 can be attached to End Housings 100 , 101 by an adhesive such as epoxy, whilst being supported in a precision jig as will be well understood by a person skilled in the art.

the joint housing items

are made of aircraft aluminium.

the aluminium

is anodised.

the link items

comprise a precision moulding of carbon-fibre.

the link items

are attached to joint housing items by an adhesive such as epoxy, whilst being supported in a precision jig.

Robot CMM Arm

can be mounted onto a number of different structures in different orientations using a number of different mounting means to suit the application that it is used for.

Mounting the Robot CMM Arm 1 to a surface 7

can be by many means 104 including bolting down with bolts 107 , magnetic mounting, vacuum mounting and clamping. It is important that the mounting means 104 used is stiff enough so as not to introduce movement between the mounting plate 8 and the surface 7 during operation of the Robot CMM Arm 1 , thus rendering the Robot CMM Arm 1 less accurate.

the Robot CMM arm 1

is normally mounted on the horizontal mounting surface 112 of a portable stand 110 using a standard 3.5′′ ⁇ 8 thread 116 .

the stand 110

has three wheels 111 that can be locked.

the stand 110

has retractable feet 113 .

the stand 110

has a large footprint to avoid it toppling over. The footprint is larger than for a corresponding Manual CMM Arm because the operator takes part of the arm load of a Manual CMM Arm through his feet, which reduces the torque on the stand 110 .

the mass of the stand 110

is larger than for a corresponding Manual CMM Arm stand because the Robot CMM Arm 1 is heavier than a corresponding Manual CMM Arm.

the stand 110

has an extensible vertical member 115 to raise or lower the base of the Robot CMM Arm.

the stand 110

must be used on a stiff floor surface and not on a carpet or compressible floor covering material.

the stand 110

will preferably be heavy so that the dynamics of the Robot CMM Arm do not cause it to rock; the control of a portable Robot CMM Arm mounted on a stand limits angular accelerations and velocities to avoid rocking the stand 110 and losing accuracy.

An example of a stand 110 for short reach Robot CMM Arms

is stand number 231-0 weighing approximately 100 kg and manufactured by Brunson Instrument Company (US) that is suitable for short and medium reaches. Additional weights may be rigidly attached to the base of the stand 110 to increase its stability. Long reach Robot CMM Arms require a larger and sturdier stand. Referring to FIG.

the Robot CMM Arm 1

can be rigidly mounted on a stable table 120 such as an optical bench or granite block that can be isolated from vibrations travelling through the floor 119 by vibration absorption means 121 situated above the supports 122 .

the Robot CMM Arm 1

can be mounted directly to the floor 119 .

the Robot CMM Arm 1

can be mounted onto a surface plate 123 mounted on the floor 119 .

the Robot CMM Arm 1

is mounted on a rail axis 124 on which it travels across the floor 119 .

the Robot CMM Arm 1

is shown in three different positions A, B, C along rail axis 124 .

a second Robot CMM Arm 1

is mounted on a second rail axis 124 and is shown in two different positions D and E.

the two rail axes

are preferably parallel. This means that two Robot CMM Arms 1 can move independently and measure both sides of a large object 9 such as a motorcycle, car or large vehicle.

the rail axis 124

is preferably linear.

the rail axis 124

is preferably mounted above the floor 119 such that it can be removed and reinstalled in a different location; alternatively, the rail axis 124 can be permanently embedded in the floor 119 .

the rail axis 124

can be manually driven, motor driven in response to manual actuation preferably via a button, or preferably CNC driven.

the Robot CMM Arm 1

will not be as stable whilst translating along the rail axis 124 as when stationary. It is preferable that the Robot CMM Arm 1 does not measure whilst translating along the rail axis 124 and instead the rail axis 124 is used to move the Robot CMM Arm 1 from one measurement location to another such as from A to C via B.

the Robot CMM Arm

can measure during translation along the rail axis 124 but the accuracy will normally be reduced; this situation is most likely when the rail axis 124 , is part of a large machine to which the Robot CMM Arm 1 is mounted. Referring now to FIG.

two Robot CMM Arms 1

can be mounted on the same rail axis 124 and move independently.

Each Robot CMM Arm 1 movement along the rail axis 124

can be manually driven, motor driven in response to manual actuation preferably via a button, or preferably CNC driven.

a suitable application

is the measurement of a car prototype in a design studio. This means that the productivity of a measuring installation with four Robot CMM Arms 1 , two moving independently on each of two rails 124 , can be double that of a measuring installation in which there is only one Robot CMM Arm on each rail axis 124 . Referring now to FIG.

the Robot CMM Arm 1

is mounted on a vertical axis 133 that can move the base of the Robot CMM Arm 1 vertically upwards and downwards.

the vertical axis 133

can move horizontally on a rail axis 124 .

the vertical axis 133

can be manually driven, motor driven in response to manual actuation preferably via a button, or preferably CNC driven.

the vertical axis 133

can be provided for one or both Robot CMM Arms 1 in the twin opposing Robot CMM Arm configuration shown in FIG. 7D or the vertical axis 133 can be provided for one or both arms in the Robot CMM Arm configuration shown in FIG. 7E . Referring now to FIG.

two Robot CMM Arms

are mounted on a moving multiple arm base 134 that moves on the rail axis 124 .

the two Robot CMM Arms

are separated by a suitable distance S such that the working overlap is sufficient to eliminate any unreachable gap between the robots in the working volume.

shorter Robot CMM Arms

are more accurate than longer CMM arms. It is an object of this embodiment that the horizontal rail 124 and vertical axis 133 , either separately or in combination, will mean that a shorter Robot CMM Arm can be used.

An example of such an object 9

is a section of pipe in a gas pipeline that is being measured in and around surface areas that have been corroded; in this example it is easier and less expensive to mount the Robot CMM Arm 1 on the pipe than to build a temporary structure of sufficient stability adjacent to the pipe.

the adaptor 136

can be a magnetic mount for ease of mounting and dismounting of the Robot CMM Arm 1 or any other mounting means 104 may be used.

an adaptor 136

is not required and the Robot CMM Arm 1 may be mounted directly onto the object 9 .

the Robot CMM Arm 1

is mounted adjacent to a processing machine 137 to which an object 9 is mounted.

the processing machine 137

is surrounded by an enclosure 138 with an automatically operated sliding door 139 .

the Robot CMM Arm 1

can measure the object 9 in the machine 137 .

the enclosure 138 and sliding door 139

are required for processing machines 137 in which environmental pollution that may be harmful to the Robot CMM Arm 1 is contained within the enclosure during processing. Some processing machines 137 do not generate environmental pollution harmful to a Robot CMM Arm 1 and do not require enclosures 138 with sliding doors 139 .

a smaller Robot CMM Arm 1 with a short reach 80

can be mounted directly onto the machine 137 such that the Robot CMM Arm 1 is closer to and within reach of the object 9 ; a sliding door is needed to protect the Robot CMM Arm 1 mounted on the processing machine 137 if the processing machine 137 generates harmful environmental pollution.

the Robot CMM Arm 1

is mounted between four processing machines 137 such that the Robot CMM Arm 1 can measure an object 9 mounted in each of the four processing machines 137 .

the Robot CMM Arm 1

is mounted between three work areas 142 . Each work area can contain one object 9 .

a work area 142

may contain one of: no object 9 , an object 9 to be measured, an object 9 being measured, an object 9 that has been measured, an object 9 that is being transferred into or out of the work area 142 .

An object 9 in a work area 142

may be precisely located on a jig in a known position and orientation relative to the Robot CMM Arm coordinate system 363 ; alternatively it may be approximately located by some means such as aligning the object 9 by human eye to markings on the floor.

An object 9

may be located in the work area by any method known to those skilled in the art.

Each object 9 in each work area 142

may be a different part with a different part number or each object may be the same part with the same part number.

One advantage of having several work areas 142 around the Robot CMM Arm 1

is that work may be loaded for automatic measuring overnight, thus increasing the utilisation of the Robot CMM Arm 1 .

a second advantage

is in keeping the Robot CMM Arm 1 fully utilised by replacing a measured object 9 with an unmeasured object 9 at a first work area 142 , whilst the Robot CMM Arm 1 is measuring another object 9 at a second work area 142 .

the Robot CMM Arm 1

is mounted on a low, robust bridge 118 traversing a work area 142 on which an object 9 is situated.

the Robot CMM Arm 1 and the Bridge 118

are designed in such a way that all of the upper side of the object 9 can have an operation performed on it by a probe 90 mounted at the probe end 3 of the Robot CMM Arm 1 .

An object 9

must be comparatively flat to fit under the bridge 118 and still have an operation performed on any area of it.

the bridge 118

is stiff, robust and firmly mounted to the floor 119 such that there is no significant deflection as the Robot CMM Arm 1 moves.

a major application area for this embodiment in which the Robot CMM Arm 1 is mounted on a bridge

is the optical inspection of sheet metal.

the object 9

which may be a sheet metal item undergoes an upstream process such as being formed in a press.

the object 9

is manually transferred to and placed in the work area 142 .

a mechanism

such as an automatic conveyor or material handling robot may automatically place the sheet metal in the work area 142 .

the object 9

is inspected by at least one probe 90 mounted on the Robot CMM Arm 1 .

a data output from the inspection process

there is a data output from the inspection process.

the data

may be created from an automatic comparison of the captured data in the inspection process with a CAD model of the ideal object 9 .

the data output

may be either statistical data or complete inspection data.

the object 9

is removed from the workplace either manually or automatically.

the data output

is used to directly or via the collection and analysis of process statistics make changes to the parameters controlling the upstream process.

the data output

is used to physically change the tooling used in the upstream process.

a linear rail 124

is provided on top of the bridge 118 for moving the Robot CMM Arm 1 to inspect a larger object 9 .

the Robot CMM Arm 1

is mounted on the end of a protruding support that is mounted to one side of the work area 142 and positions the Robot CMM Arm 1 above the middle of the work area 142 .

the Robot CMM Arm 1

can perform an operation on an object 9 that is situated on an object displacing means and that the object 9 is displaced at least once during the operation.

the Robot CMM Arm 1

is mounted adjacent to a rotary table 820 on which the object 9 is located rotating about Axis A.

the rotary table 820

can be manually rotated and locked in a new position with a clamp 822 .

the rotary table 820

can be rotated by motorised means 821 such as a motor or a servo drive.

Automated rotation of the rotary table 820

can be controlled by the Robot CMM Arm System 150 or any other means such as manual actuation via a button or a slave control means.

An angular position recording device 823

such as an encoder is typically attached to the axis A of the rotary table 820 .

the object 9

is displaced four times by moving the rotary table to four positions at 90 degree intervals to give the Robot CMM Arm 1 access to perform an operation on all quadrants of the object 9 .

the Robot CMM Arm 1

does not carry out an operation such as measurement whilst the object 9 is moving.

An advantage of rotating the object 9 on a rotary table 820

is that an operation may be performed on an object 9 that is larger than the reach 80 of the Robot CMM Arm 1 ; it is particularly suitable to wide and or tall objects.

a second advantage of rotating the object 9 on a rotary table 820

is in the case of a complex object 9 to give different access orientations to the Robot CMM Arm 1 to access difficult to enter parts of the object 9 .

the Robot CMM Arm 1

is mounted adjacent to a linear table 824 on which the object 9 is located linearly displacing along axis B.

the linear table 824

has similar position measurement possibilities, control possibilities and advantages to the rotary table 820 .

multiple-axis tables with 2 or more axes

may be used to displace the object. It will be understood by an expert in the field that each type of table axis or axis combination will have different advantages for different classes of object size and shape.

the Robot CMM Arm 1

is stationary and carries out an operation such as non-contact measurement or a contact operation with a tool whilst the object 9 is moving.

both the Robot CMM Arm 1 and the object 9

move simultaneously whilst an operation such as non-contact measurement or a contact operation with a tool is being performed.

further control algorithms

are required to transform coordinate systems to a common coordinate system such as the object coordinate system.

the object 9

may or may not be clamped or otherwise attached to the table so as to eliminate relative movement between the object 9 and the table.

the table

In all table embodiments in which the object 9 moves during the operation, the table must be accurate and the object must not move relative to the table to enable accurate operations to be performed. Tables of the necessary size and accuracy are normally expensive items.

the Robot CMM Arm 1

is mounted in an orientation that is not a horizontal surface and in which the Robot CMM Arm 1 is not approximately vertically upright.

the Robot CMM Arm 1

is mounted orthogonal to a wall 125 .

the Robot CMM Arm 1

is supported from a gantry 126 ; alternatively it could be Supported form a ceiling.

the Robot CMM Arm 1

is mounted on a platform 127 with a surface at 60 degrees to the vertical.

the Robot CMM Arm 1

is mounted on a large, 3-axis conventional CMM such as are employed in automotive companies.

the Robot CMM Arm 1

has significant mass, it is typically expected to weigh from 18-32 kg depending on its accuracy and the reach of the arm, but it could weigh more or weigh less.

a light Robot CMM Arm based on this present invention

could be designed with a mass substantially below 12 kg.

the Robot CMM Arm

is preferably attached to a Moving bridge CMM 129 and Supported vertically downwards from the Vertical column 130 of the Bridge 131 .

the Robot CMM Arm 1

can access all parts of the object 9 being measured.

the scope of this invention

is not limited to the Robot CMM Arm 1 being mounted vertically downwards from the vertical column 130 of a bridge type conventional 3-axis CMM 131 with 3 linear axes or from the horizontal arm 132 of a Horizontal Arm CMM 128 also with 3 linear axes.

the Robot CMM Arm 1

can be mounted from any substantial conventional CMM in any orientation with any number of axes.

the Robot CMM Arm 1

is mounted on a rotating wedge base 135 at angle A to the vertical axis of rotation B.

the scope of this invention

is not limited to the embodiments of the installation of the Robot CMM Arm shown in FIGS. 7 A-G and FIGS. 8 A-F. It is a purpose of this invention that the Robot CMM Arm 1 can be mounted at any orientation in free space. It is a further purpose of this invention that the Robot CMM Arm 1 can be mounted from either a fixed or a movable structure. It is a further purpose of this invention that the Robot CMM Arm 1 can be mounted on any moving structure to translate or orientate the Robot CMM Arm in six degrees of freedom. The moving structure can move at any time during or between measurements. It is a further purpose of this invention that Robot CMM Arms 1 can be provided in an installation in any quantity and any arrangement.

the Robot CMM Arm 1

is preferably mounted to a surface 7 that is rigid with respect to the object 9 being measured.

there can be a continuous relative movement between the Robot CMM Arm 1 and the object 9 being measured

such as caused by large machinery operating nearby that transmits vibrations through the floor.

there can be an occasional relative movement between the Robot CMM Arm 1 and the object 9 being measured

such as caused by a lorry driving by or an accidental knock to the object being measured.

there can be slow relative movement between the Robot CMM Arm 1 and the object 9 being measured

such as caused by thermal expansion of the structure on which the Robot CMM Arm and the object are mounted. Referring to FIG.

the relative movement in 6 degrees of freedom

can be measured by an independent measuring device.

an independent measuring device

examples include the laser tracker by Leica and, preferably, a Photogrammetric tracker 140 by Krypton.

the Robot CMM Arm 1 and the Photogrammetric tracker 140

are mounted on a surface plate 123 .

the object 9

is mounted on a floor 119 subject to movement such that there is significant relative movement between the object 9 and the surface plate 123 .

Photogrammetric targets 141

are attached to the object 9 such that a minimum of 3 targets and preferably more are visible to the Photogrammetric tracker 140 at any time during the measuring process.

Time synchronisation

can be by any method commonly known to an expert in the trade including the triggering of measuring devices simultaneously, time stamping all measurements to a common clock for later processing. Such processing can include temporal interpolation when the relative movement measurement and the Robot CMM Arm measurement are not taken at the same instant.

the process of calibrating the Photogrammetric Tracker 140 measurements to the Robot CMM Arm 1 measurements

is well known to a person skilled I the trade. The result is measurements of Object 9 that are corrected for measured relative movement between the Robot CMM Arm 1 and the object 9 .

the reach 80 of the Robot CMM Arm 1

depends on the application.

the Robot CMM Arm 1 of this first embodiment

is provided as a range of portable Robot CMM Arms 1 with different reaches 80 .

these reaches 80

might be from 0.5 m to 5 m with reaches 80 of 1 m and 1.5 m likely to be the most requested by component customers, reaches 80 of 2 m to 3.5 m to be those requested most by automotive customers, and reaches 80 of 2.5 m to 5 m to be those requested most by aerospace customers.

the reach 80 of the Robot CMM Arm 1 invention

is not constrained in this disclosure; Robot CMM Arm reach 80 can be longer or shorter than the ranges quoted.

Robot CMM Arms

can have longer reaches than the 2 m effective limit of Manual CMM Arms. This means that applications requiring reaches longer than 2 m (for which Manual CMM Arms are not practicably supplied) can be carried out by Robot CMM Arms.

This first embodiment of a Robot CMM Arm 1

is a portable system and is not designed for high angular velocities and accelerations in order to limit the weight of the Robot CMM Arm 1 .

Other embodiments of a Robot CMM Arm 1

can be designed for much higher angular velocities and accelerations.

a lower maximum angular velocity for longer reaches

is accepted in this first embodiment.

the key difference across the range

is a variety of lengths of the links 102 .

a Control Box 159

is mounted onto the Base 4 of the Robot CMM Arm 1 .

Power

is supplied by means of a power cable 155 connected to a power connector 195 .

a power switch 156 and power LED 157

are provided.

An interface connector 194

is provided for, amongst other things, connecting to a probe box 295 via a probe box to arm cable 296 .

a laptop 151

is connected by means of a Laptop communication cable 152 to laptop connector 197 .

a Pendant 153

is connected by means of a Pendant communication cable 154 to pendant connector 198 .

a network 200

is connected via network connector 199 .

Both the Pendant 153 and the laptop 151

can operate for a period from batteries 163 , 164 .

the pendant battery 163

is recharged by placing the pendant in a recharge point 158 with electrical contacts 328 ; power connections are automatically made when the pendant is correctly placed in the recharge point.

the laptop battery 164

is recharged from mains electricity.

a touch trigger probe 92

makes automatic power connection 160 and trigger connection 161 when mounted on the Robot CMM Arm 1 .

An Optical probe 91

makes automatic power connection 160 , trigger connection 161 and probe communications connection 162 when mounted on the Robot CMM Arm 1 .

a Control PCB 172

is connected to ground line 165 and +5 Volt power rail 166 .

Seven motors 176

are connected to seven amplifiers 175 by motor cables 196 and are driven from seven +/ ⁇ 10V control signals 168 output from the Control PCB 172 to the amplifiers 175 .

the Control PCB 172

is connected to seven Joint PCBs 173 by a serial bus 169 .

the Control PCB 172

has two further communication connections 152 and 154 for communicating with the laptop 151 and the pendant 153 respectively.

a +24 Volt power rail 167

provides power to the amplifiers 175 .

a power supply unit 171

is connected to a power supply cable 155 , a battery 170 , ground 165 and power rails 166 , 167 .

At least one Joint PCB 173

is connected to a probe 90 with power 160 , trigger 161 and, where applicable, communications 162 .

All seven motors 176

have brakes 177 which are driven by signals from the Joint PCBs 173 .

the Internal CMM arm 5

comprises seven CMM encoders 178 attached to the joint PCB 173 . Seven encoders 179 mounted on the seven motors 176 driving the Exoskeleton 6 are attached to the joint PCB 173 .

a thermocouple 180 mounted on the Internal CMM Arm 5

is connected to each Joint PCB 173 .

a strain gauge 181 mounted on the Internal CMM Arm 5

is attached to each Joint PCB 173 .

Two limit switches 182

are connected to each Joint PCB 182 .

Two operator Buttons 183

are connected to the Joint PCB 173 of the 7 th joint.

Touch sensors 184

are connected to each Joint PCB 173 .

Each Joint PCB 173

is connected to ground line 165 and +5 Volt power rail 166 .

a trigger bus 174

is connected to each Joint PCB 173 and the Control PCB 172 ; it is used for latching the seven CMM encoders 178 .

a Control PCB 172 and four Joint PCBs 173

are connected in series with a Bus 193 passing through four Slip-ring units 188 located at each axial CMM Joint 1 , 3 , 5 , 7 51 , 53 , 55 , 57 . From one to three joints are driven by each Joint PCB 173 and the Control PCB 172 can also drive one or more joints.

Each Slip-ring unit 188

has the capacity for 28-wires, but the number of wires could be more or less than 28.

the Bus 193

also has 28 wires.

a Control bus 394

is incorporated in the Bus 193 and uses 5 wires.

the Control bus 394

can be proprietary or can be a standard such as the CAN bus.

the CAN bus

is a high-speed low latency control bus.

the CAN bus and associated circuitry

has limitations when driving 7 axes. A faster control solution is to use two CAN buses and drive 4 axes with the first CAN bus and 3 axes with the second CAN bus.

Intelligent drive amplifiers 175

are located next to each motor 176 and connected to a Joint PCB 173 or a Control PCB 172 by a Control bus 394 as well as 24V power and 0V ground. Examples of Intelligent drive amplifiers 175 are the EPOS 24/1 and 24/5 supplied by Maxon Motor, USA. Alternatively, the intelligent drive amplifier functionality can be integrated into the Joint PCB 173 and the Control PCB 172 . The control functionality including servo loop closure takes place in the Control 395 .

the Control 395

is the PCI 208 supplied by Trio Motion Technology, UK.

the PCI 208

has two Control bus 394 outputs permitting fast servo control; these Control bus 394 outputs are the CAN bus standard.

the 5 or 10 wires of the CAN buses

replace around 10 wires for each of the seven motor/encoders that are normally wired directly all the way from the Motor 176 to the Control 395 . Since the number of wires in a Slip-ring 188 is limited by practical considerations such as size and weight, the use of a Control bus 394 that reduces the number of wires in the arm by around 60 wires, permits the use of Slip-rings 188 providing infinite rotation in the axial CMM Joints 1 , 3 , 5 , 7 51 , 53 , 55 , 57 .

the Bus 193

provides power, signal and communications to one or more Probes 90 that might be contact or non-contact of which a Stripe probe 97 is most commonly used.

a Stripe probe 97

is most commonly used.

the provider of a third party probe 90

can use the through channel for any combination of power, ground, signals and buses that is required within the wiring specification limitations of the Robot CMM Arm System 150 .

a typical number of wires provided in the through channel

is 9 but could be less than 9 or more than 9.

the interface connector 194

can also provides synchronisation signal connections for synchronising the Robot CMM Arm 1 and the Probe 90 .

a Control PCB 172

three Joint PCBs 173 , a PC 151 , a Pendant 153 , a network 200 and an Optical Probe PCB 270 are connected together by means of an Ethernet network.

a novel feature of this embodiment of the Robot CMM Arm invention

is the use of a daisy-chain Ethernet arrangement wherein an Ethernet switch 396 is provided at each intermediate PCB in the daisy-chain. This means that the number of cables running up the Robot CMM Arm 1 is reduced by 4 ways for each intermediate PCB, in this case a reduction of 12 ways.

the Control PCB 172

contains an Ethernet Switch 396 such as the 5-way Micrel KS8995.

Each Joint PCB 173

is a dual axis Joint PCB and can have up to two joints connected to it.

Each Joint PCB 172

contains an Ethernet Switch 396 such as the 3-way Micrel KS 8993 .

Each PCB

has a processor with an MCA Ethernet Controller 386 .

the Ethernet used

is 100BaseT; its bandwidth is not significantly reduced by the use of slip-rings.

the scope of this invention

is not limited to the architecture of the Robot CMM Arm System 150 disclosed in this first embodiment but includes all architectures that have the technical effect of the Robot CMM Arm System 150 .

the Control Box 159

is separate from the Robot CMM Arm 1 and connected to the base 4 of the Robot CMM Arm with a cable.

This architecture

can be necessary for Robot CMM Arms where the items in the Control Box 159 require the Control Box 159 to be too big to sensibly fit at the base 4 if the Robot CMM Arm is to be portable.

the architecture of the first embodiment

is preferred because the portable Robot CMM Arm is a single unit without the increased manufacturing cost and location footprint of a separate control box 159 .

a full size personal computer

is used instead of a laptop 151 and the Control PCB 172 is mounted in the personal computer on a standard bus such as the PCI bus; alternatively a network of several computers in a rack are used.

the pendant

is not supplied and the laptop 151 is used to control the Robot CMM Arm 1 .

a connector

is supplied for connecting one or more external axes to the Robot CMM Arm 1 , that are driven by the Control 395 . Examples of such external axes are a linear rail or a turntable.

each CAN bus 394

may be configured to use just 3 wires.

a CAN bus 394

is made available for the systems integrator to interface to by means of a connector in the control panel 159 .

Digital 10 from the Trio Control 395

can also be made available for the systems integrator to interface to by means of a connector in the control panel 159 .

the Emergency Stop circuit

is passed all the way up the arm and can be actuated by sensors or processors in the Joint PCBs 173 or an attached Optical Probe 91 .

the Emergency Stop circuit

may be provided for the systems integrator to interface to by means of a connector in the control panel 159 . Fuses may be provided in the control panel 159 for replacing or resetting; they may be accessible from the control panel or by removing the control panel. Connector jumpers may be provided for any connector through which the Emergency Stop circuit runs.

the Control 395 functionality

can be integrated into the Joint PCB 173 or the Control PCB 172 or an Intelligent Drive Amplifier 175 .

the Internal CMM Arm 5

comprises angular encoders 178 at each CMM joint 51 - 57 .

the scope of this invention

is not limited to angular encoders or to any particular design of angular encoders but can utilise any accurate form of angle measuring device.

the resolution and accuracy of an angular encoder

is limited by several factors including: the diameter of the encoder, the number of printable edges, the linearity of the edges, the linearity of the read head, the amount of interpolation and irregularities in the encoder.

the Internal CMM Arm 5

uses CMM encoders 178 such as those manufactured by Renishaw or Micro-E Systems, USA.

the CMM joints 21 , 22 towards the base end 2 of the Internal CMM arm 5

have larger diameter encoders because there is a longer distance from the CMM encoder 178 to the probe end 3 .

the intermediate joints 23 - 24 at the elbow of the Internal CMM Arm 5

have medium diameter encoders because there is a medium distance from the encoder 178 to the probe end 3 .

the far joints 25 - 27 at the wrist of the Internal CMM Arm 5

have small diameter encoders because there is a small distance from the encoder 178 to the probe end 3 .

the smaller encoder diameters

reduce the weight of the arm carried by the operator at full stretch, make it compact and easy to handle. In the case where there is a large virtual reach 81 caused by the optical probe 91 , it can be important to have higher resolution encoders at the joints 23 - 27 towards the probe end of the arm.

an Internal CMM Arm encoder 178

comprises Renishaw RESR Angular encoders 185 with a 20 micron scale pitch are used together with one or more Renishaw RGH 20 read heads 186 per joint.

two or more read heads 186

are mounted per encoder 185 , they are mounted at either 90 degs to each other as shown in FIG. 12 or preferably 180 degs to each other, but the read heads could be at any other angle to each other.

a 52 mm diameter RESR with 8192 counts

is used on each of CMM Joints 23 - 27 providing a quoted accuracy of +/ ⁇ 5.6 arc seconds per joint.

a 150 mm diameter RESR with 23,600 counts

is used on each of CMM Joints 21 and 22 providing a quoted accuracy of +/ ⁇ 1.9 arc seconds per joint.

the output of each Renishaw read head 186

goes to a Renishaw RGE interpolator 187 .

the output from each Renishaw interpolator 187

feeds into the Joint PCB 173 .

the advantage of using two or more read heads

is twofold.

an angular encoder system

can be provided as a single unit comprising encoder, one or more read heads, interpolator, averaging and error mapping, with one connection from the angular encoder system to the Joint PCB 173 . It is expected that companies such as Renishaw will in the future provide such an angular encoder system of around 50 mm diameter with accuracies of 0.1 arc second.

a Dual pattern encoder 860

comprises an encoder Disk 861 that has an edge Pattern 862 printed around the circumference of each of its two sides A, B, one read-head 186 reading the Pattern 862 on Side A and a second read-head 186 reading the Pattern 862 on Side B, the two read-heads being situated approximately 180 degrees apart.

a Dual pattern encoder mapping apparatus 863

comprising an Accurate rotational stage 864 such as the ABR1000 provided by Aerotech Inc, US, a rotating Clamping mechanism 865 such as a specially shaped bolt for clamping a Disk 861 onto the rotating part of the Accurate rotational stage 864 , two stationary Read-heads 186 situated at approximately 180 degrees to each other and on opposite sides of the Disk 861 such that a first Read-head 186 can read a first Pattern 862 on side A and a second Read-head 186 can read a second Pattern 862 on side B as the Patterns 862 move relative to the stationary Read-heads 186 , and a Mapping system 866 connected to the Accurate rotational stage 864 and the Read-heads 186 with Cables 868 .

an Accurate rotational stage 864

such as the ABR1000 provided by Aerotech Inc, US

a rotating Clamping mechanism 865

such as a specially shaped bolt for clamping a Disk 861 onto the rotating part of

the Accurate rotational stage 864

is much more accurate than the accuracy to which the Dual pattern encoder 860 is expected to perform.

the Mapping system 866

(a) controls the movement of the Accurate rotational stage 864 , (b) reads signals from the Read-heads 186 and (c) outputs a Map 867 .

a Disk 861

is shown on which the Centre of Pattern A 869 , the centre of Pattern B 870 and the Centre of rotation 871 of the axis of the joint carrying the Dual pattern encoder 860 are represented.

the Map 867

is a digital file and contains mapping information providing (i) the Magnitude M of the misalignment of the two Patterns 862 relative to each other, (ii) the Orientation 872 of the misalignment, (iii) an error map for each Pattern 862 mapping the angular errors between the Accurate rotational stage 864 and the printed edges on each Pattern 862 and covering at least print non-linearities of the edges on each Pattern 862 .

the two Patterns 862

are printed to be in reasonable axial alignment with a typical axial misalignment M of 10 microns but this misalignment M could be much more than 10 microns or much less than 10 microns.

the Orientation 872 of the misalignment M

is marked manually on the Disk 861 .

the Sides A and B

are marked manually on the Disk 861 .

the Orientation 872 of the misalignment

is typically known with reference to absolute reference marks on the Pattern 862 read by Read-head 186 .

the process of generating the Map 867

is well known to those skilled in the art. Reference marks on each Pattern 862 are provided to reference the error map.

Up to seven mapped Dual pattern encoders 860

can be provided in a Robot CMM Arm 1 .

a Map 867

is provided for each Dual pattern encoder 860 .

a Joint of the Robot CMM Arm 1 in which there is a Dual pattern encoder 860

is stepped from one rotational axis limit to the other using steps of typically 5 degrees but the step could be more or less than 5 degrees.

Readings from each Read-head 186

are taken at each step to form a set of Readings. The set of Readings are corrected using the error maps of the Map 867 to provide Corrected readings.

the Corrected readings

are processed using the misalignment and misalignment orientation information in the Map 867 to calculate the position of the Joint centre 871 relative to the Centres of Pattern A 869 and Pattern B 870 in a process well understood to those skilled in the art.

the calibrated position of the Joint centre 871 relative to the Centres of Pattern A 869 and Pattern B 870

is used to correct readings from the Dual pattern encoder 860 and make the Robot CMM Arm 1 more accurate.

the calibrated Dual pattern encoder 860

provides angles more accurately than an equivalent single pattern encoder with two read-heads because (a) there are effectively two, independent error-mapped encoder systems rather than one and the results of these two systems provide a better average than for an encoder system with one pattern, (b) errors from non-perpendicularity of the Disk 861 relative to the Joint axis are automatically averaged out.

the Dual pattern encoder 860

has the same number of components, weighs the same and occupies the same volume as an equivalent single pattern encoder with two read-heads.

the Dual pattern encoder 860

may be provided with both patterns 862 on the same side of the Disk 861 in the form of inner and outer radial patterns.

Dual pattern encoder 860

In a further embodiment for a lower cost Dual pattern encoder 860 , if the Patterns 862 are aligned in the manufacturing process of the Disk 861 to a small enough misalignment M, then it is not necessary to have the extra process of mapping the Dual pattern encoder 860 whilst still gaining the benefits of automatically averaging out any axial misalignment in fitting to a joint of the Robot CMM 1 . In an alternative embodiment for a more accurate Robot CMM 1 , two Dual pattern encoders 860 are provided at each joint, preferably located either side of the joint centre.

the portable Robot CMM Arm

operates quietly and can be used in office environments. It is important that the level of emitted audible noise is kept to a minimum in the design. Inherently low-noise drive systems including motors and gearing methods are selected to minimise the emission of audible noise. Fundamentally, the level of audible noise output increases with the velocities and accelerations at which the Robot CMM Arm is driven. Reducing the velocities and accelerations has little impact on cycle time in many applications. This is because typically 90% of the cycle time is taken up with measuring which is a slow process and only 10% can be reduced by means of increasing speed.

control system

can be set by the user to scan quietly with low velocities and accelerations.

the Robot CMM Arm

minimises the emission of electromagnetic radiation by incorporating drive system components with low electromagnetic radiation and providing shielding around the components emitting the most electromagnetic radiation.

the Robot CMM Arm 1

is driven by electric motors 176 that are brushed DC servo motors with encoders.

the drive systems in this invention

are not limited to electric motors of any kind, but can be driven by a range of different power systems including hydraulics or pneumatics. Hydraulics and pneumatics can introduce less vibration into the Robot CMM Arm than electric motors with encoders.

Electric motors 176

can be AC or DC servo motors, stepper motors or other forms of motor; the motors 176 can be brushed or brushless.

a high speed control loop

is provided in which the electric motors 176 and encoders 179 close the loop; this high speed loop is satisfactory for traversing the Robot CMM Arm 1 .

a high accuracy control loop

is provided for contact measurement in which the CMM encoders 178 are used to close a slower higher level loop outside the high speed control loop.

the CMM encoders 178

can be used for position feedback; the Exoskeleton encoders 179 are not then required.

stepper motors

can be used in an open loop format without any position sensing in the control loop.

Robot CMM Arms 1

that can survive an impact with a car body. Due to the presence of the Internal CMM Arm 5 , for most applications it is not essential to have low backlash in the drive train elements. Low cost and low mass drive train components such as belt drives can be used.

one motor 176

is used to drive each joint 61 - 67 .

Robot CMM Arm

In moving a drive unit closer to the base end of the Robot CMM Arm, it is possible to reduce the specification of the drive units situated between the moved drive unit and the base because these previous drive units do not have to work as hard moving the drive unit that has been positioned closer to the base end. Each reduced specification drive unit is lighter and in turn may require other less performant drive units elsewhere. Another benefit from moving a drive unit closer to the base end come from the reduced stress on some Exoskeleton segments enabling them to be designed to be lighter. It can thus be seen that there is a compounding beneficial advantage from moving just one drive unit closer to the base end. It is an object of this invention that the Robot CMM Arm be optimised to minimise its weight and energy consumption for a defined specification, by means including positioning drive units as close to the base end as possible.

JointCentres 3 , 5 [ 23 , 25 ] and their motors 176

are far from the base end 2 compared to a low inertia embodiment of the Robot CMM Arm 1 , in which JointCentres 3 , 5 23 , 25 and their motors 176 are nearer the base end 2 .

the motors

do not have to be adjacent to the joint centres; in alternative embodiments, JointCentres 3 , 5 23 , 25 are distant from the base end 2 , the motors 176 are closer to the base end 2 and a torque transmission means transmits the motor torque along ExoskeletonSegments 3 , 5 43 , 45 from the motors 176 to JointCentres 3 , 5 23 , 25 .

Typical savings from the positioning of drives closer to the base end

can be greater than 1 kg in Robot CMM Arm mass and more than 10% savings in power consumption.

the base 41 of the Exoskeleton 6

is rigidly attached to the base 31 of the Internal CMM Arm 5 such that there can be no significant relative movement between the two bases 41 and 31 and that forces and torques are transmitted through this rigid attachment.

a number of Transmission means 72 - 78

are provided, which may be none, one or more than one for each CMM Segment 32 - 38 .

Each of the Transmission means 72 - 78

is in physical contact with the corresponding Exoskeleton Segment 4248 and the corresponding CMM segment 32 - 38 .

the centres and axes of the CMM Joints 51 - 57 and the Joints 61 - 67

are in substantially the same positions. Factors resulting in slight misalignments of these joint centres and axes include:

Transmission Means 10

will be different for 6-axis and 7-axis Robot CMM Arms 1 .

the arrangement of Transmission Means 10

will be different for short reach and long reach Robot CMM Arms 1 .

the arrangement of Transmission Means 10

will be different for different joint arrangements including different positions and orders of joint.

Any number of Transmission Means

can be used from one discrete Transmission Means to a continuum of contact throughout the length of the Robot CMM Arm.

One Transmission Means

in order to position and orient the probe 90 , if there is only one Transmission Means, it must be Transmission Means 8 78 between CMM Segment 8 38 and Exoskeleton Segment 8 48 . However, a 6 or 7 axis arm has redundancy and the elbow is then free to move under gravity or inertial accelerations. This free movement will result in a second ‘inadvertent’ Transmission Means where the CMM Joint 4 54 impacts the Exoskeleton Joint 4 64 .

the first Transmission Means

must be Transmission Means 8 78 .

the second Transmission Means

must be situated between the JointCentre 2 22 end of CMM Segment 3 33 and the JointCentre 6 26 end of CMM Segment 6 36 in order to control the elbow. If the second Transmission Means is towards JointCentre 2 22 , then the drives on the Exoskeleton 6 will need to be heavy and powerful all the way to the first Transmission Means where the weight of most of the arm is supported; this will result in a much heavier than necessary Robot CMM Arm 1 .

Three Transmission Means

Three Transmission Means in addition to the rigid base connection is the preferred number of Transmission Means of the first embodiment of the Robot CMM Arm 1 .

the Three Transmission Means

are located: near and before JointCentre 4 24 , near and before JointCentre 6 26 and Transmission Means 8 78 before the probe end 3 .

This arrangement of Transmission Means

has the following advantages:

a continuous elastic medium

can be provided between the Internal CMM Arm 5 and the Exoskeleton 6 .

the intermediate volume between the CMM Arm 5 and the Exoskeleton 6

could be filled with a quantity of small rubber spheres that are coated in adhesive such that they adhere to each other and do not flow down or around the intermediate volume in different spatial orientations.

the intermediate volume

could be filled with a material such as bubble-wrap in which pockets of air are trapped in a plastic sheet.

the medium

can be specified to minimise the forces and torques transmitted to the Internal CMM Arm 5 .

the medium

can also be specified to minimise the misalignment of the joints of the Internal CMM Arm 5 with the joints of the Exoskeleton 6 .

the medium

can be specified so that it exhibits desired elasticities in the three component directions: radial, axial and torsional.

the medium

may be continuous throughout the intermediate volume or may be discontinuous such as to resemble discrete Transmission Means.

a continuous medium

may exhibit discontinuous properties; for example the radial, axial and torsional elasticities in different regions of the intermediate volume may vary, perhaps substantially.

Case 3

Auto-rotation can occur if Orthogonal Hinge Joint 6 26 is straight. Auto-rotation involves CMM Segments 6 , 7 36 , 37 rotating together between CMM Joints 5 , 7 55 , 57 . This is likely if there is an off-axis centre of gravity in CMM Segments 6 , 7 36 , 37 to be accelerated by gravity and Orthogonal Hinge Joint 6 26 is not in a vertical orientation. Cases 1, 2 and 3 can be prevented either by a Rotation restraining element built into an overlapping Drive Transmission Means or a separate Rotation Restraining means 940 .

Case 4

Auto-rotation can occur if CMM Segment 8 has an off-axis centre of gravity and is not driven by a Transmission Means. However, a Transmission Means 8 78 is essential and gives a Torsional drive so Case 4 can be neglected.

LockingCase 1

Orthogonal Hinge Joints 2 , 4 , 6 22 , 24 , 26 are straight with their axes horizontal. The arm is vertical if the base axis is vertical. Misalignments may result in bending moments applied to the Internal CMM Arm 5 by the Transmission means. An abuse load might result in bending moments applied to the Internal CMM Arm 5 by the Transmission means. Careful design of the Transmission Means and the stiffness of the Exoskeleton can minimise or eliminate this effect.

LockingCase 2

Orthogonal Hinge Joints 4 , 6 24 , 26 are straight with their axes vertical. If the segments of the Robot CMM Arm 1 after Joint 2 22 are horizontal then there is the situation that CMMSegments 3 - 8 33 - 38 form a single stiff ‘locked’ beam lying horizontally under gravity and supported in two or more locations. When supported at each end, the ‘locked’ beam will deflect significantly in the middle. When supported in 3 or more locations, it is likely that bending moments will arise and worse deflections be exhibited. Misalignments may result in bending moments applied to the Internal CMM Arm 5 by the Transmission means. An abuse load might result in bending moments applied to the Internal CMM Arm 5 by the Transmission means.

LockingCase 3

Orthogonal Hinge Joint 6 26 is straight and its axis is vertical. This is a sub-case of LockingCase 2. The deflections are less. LockingCase 3 may be resolved in a similar manner to LockingCase 2.

CMMJoints 2 , 4 , 6 32 , 34 , 36 in the above example Locking cases or any other Locking Case

can be avoided by either of: 1. Putting hard stops in the Exoskeleton 6 to prohibit the joint reaching 180 degs; 2. Not moving the Robot CMM into spatial orientations where locking takes place.

the Robot CMM Arm 1

is static in the horizontal spatial orientation from Joint 2 onwards.

Three Transmission Means 3 , 5 , 8 73 , 75 , 78

are provided.

Transmission Means 3 73

is located just before JointCentre 3 23 .

Transmission Means 5 75

is located just before JointCentre 5 25 .

Transmission Means 8 78

is located after JointCentre 7 27 .

Rotation Restraining means 940

are provided adjacent to Joint Centres 2 , 4 , 6 22 , 24 , 26 .

probes 90

including optical probes 91 of various masses, centre of gravity positions and moments of inertia will be attached to the probe end 2 of the Robot CMM Arm 1 .

all probes 90

will be designed such that when mounted on CMM Segment 38 , the position of the Centre of Gravity of the combined probe 90 and CMM Segment 8 38 is centred on the axis of CMM Segment 38 in the centre of the Transmission Means 8 78 .

attaching a probe 90 of high mass centred on Centre of Gravity CG 8

will not reduce the accuracy of the Robot CMM Arm because the extra mass is fully supported by the Exoskeleton 6 via the Transmission Means 8 78 .

Rotation Restraining means 940

comprises a Pin 941 and an embedded rubber O ring 942 .

the Pin 941

is rigidly attached to the Internal CMM Arm 5 and protrudes from the axis of CMM Joint 2 52 .

the O ring 942

is rigidly embedded in the Exoskeleton 6 and is aligned with the axis of Exoskeleton Joint 2 62 .

the outside diameter of the Pin 941

is significantly less that the inside diameter of the O ring 942 such that when CMM Joint 2 52 and Exoskeleton Joint 2 62 are aligned, there is a uniform radial air gap between the Pin 941 and the O ring 942 .

the object of the Rotation Restraining means 940

is to prevent auto-rotation R of CMM Segments 2 , 3 when CMM Joint 2 52 is straight. If auto-rotation R starts, it will soon be halted by the Pin 941 swinging round the Axis of JointCentre 2 22 and colliding with the O ring 942 . The air gap is maintained in normal motion of the Robot CMM Arm and prevents undesirable forces or torques being applied to the Internal CMM Arm 5 via the O ring 942 and the Pin 941 .

the Transmission Means 3 73

comprises three Transmission Blocks 201 at 120 degree spacing rigidly attached to the inside of Exoskeleton Segment 3 43 ; the Transmission Blocks 201 are made from a light material such as Aluminium.

the Bonded to the inner surface of the three Transmission Blocks 201

are two layers: an elastic material layer 203 such as neoprene and a low-friction material layer 202 such as PTFE that contacts with CMM Segment 3 33 .

the Transmission Means 3 73

do not transmit axial force because the low-friction material layer 202 permits slip between the CMM Segment 3 33 and the Exoskeleton Segment 3 43 in the axial mode.

the elastic material layer 203

is in constant compression when the Transmission Means 3 73 is assembled in position.

the elastic material layer 203

has a combined cross-sectional area, thickness and stiffness that enables it to remain within its design elastic range without rapidly increasing in stiffness during normal use or compressing a significant distance.

the elastic material layer 203

is much wider than the misalignment under abuse loads of the Internal CMM Arm 5 and the Exoskeleton 6 at that location; this protects the Internal CMM Arm from receiving high forces or torques.

the stiffness of the elastic material layer 203

is low such that it significantly compresses when supporting the maximum weight. It will be appreciated by those skilled in the art that the specification of the cross-sectional area, thickness and stiffness is a known procedure requiring accurate modelling of many factors including misalignment tolerance build-up and deflection of the Exoskeleton under abuse loads.

a benefit from the use of low-friction material 202

is that heat is not generated through friction; this means that the required drive power is minimised and the accuracy of the Internal CMM Arm 5 is maintained by eliminating thermal distortion due to frictional ‘hot’ spots.

Two Bump stops 209

are provided to prevent auto-rotation.

the Bump-stops

are attached to CMM Segment 3 33 . In normal operation, there is an air gap between Bump stop 209 and the Transmission Block 201 .

the Bump Stop 209

has a rubberised surface to reduce impact. If auto-rotation commences, then it is soon stopped by Bump-stop 209 hitting Transmission Block 201 .

Transmission Means 5 75

is similarly arranged for radial drive transmission.

the drive transmission of Transmission Means 8 78

is torsional and radial.

Transmission Means 8 7

comprises two neighbouring units a torsional drive and a radial drive.

the radial drive

is similar to that of FIG. 17 .

FIG. 18

the torsional drive of the Transmission Means 8 78 is shown in Longitudinal Section AA and Axial Section BB.

CMM Segment 8 38

is rotated by means of a torque through Transmission Means 8 78 from Exoskeleton Segment 8 48 .

the Transmission Means 8 78

comprises a Collar 204 bonded to CMM Segment 8 38 .

the Collar 204

further comprises three Driven flanges 209 spaced at 120 degrees, extending outwards radially and extending longitudinally.

Three Slotted Transmission Blocks 205 at 120 degree spacing

drive the driven flange.

Each Slotted Transmission Block 205

comprises two pads of elastic material 203 bonded to the two drive faces of the slot of the Slotted Transmission Blocks 205 .

the Slotted Transmission Blocks 205

are attached to Exoskeleton Segment 8 48 with bolts 206 using washers 207 .

the Slotted Transmission Blocks 205 , the collar 204 and the washers 207

are made from a light material such as Aluminium.

the elastic material 203

has an external low-friction material layer 202 such as PTFE that contacts with the Driven flanges 209 .

the Transmission Means 8 78

do not transmit axial forces because the low-friction material layer 202 permits some slip between the CMM Segment 8 38 and the Exoskeleton Segment 8 48 in the axial mode.

the Transmission Means 8 78

partially transmits radial forces because although the low-friction material layer 202 permits some slip between the CMM Segment 8 38 and the Exoskeleton Segment 8 48 in the radial mode, the Driven flanges 209 are situated at 120 degrees and react together to provide a correcting force to any radial movement between the CMM Segment 8 38 and the Exoskeleton Segment 8 48 .

the elastic material layer 203

is in constant compression when the Transmission Means 8 78 is assembled in position.

the elastic material layer 203

has a combined cross-sectional area, thickness and stiffness that enables it to remain within its design elastic range without rapidly increasing in stiffness during normal use or compressing a significant distance. It will be understood by those skilled in the art that an integrated torsional and radial drive could be provided as a lighter and more compact unit than the two neighbouring torsional and radial drives which have been discussed separately to better disclose the principals behind the invention.

the Exoskeleton 6

can transmit forces and torques to the Internal CMM Arm 5 using a wide range of transmission means 10 that all achieve the objective of minimising forces and torques on the Internal CMM Arm 5 so as to maximise the accuracy of the Robot CMM Arm 1 .

the scope of this Robot CMM Arm 1 invention

is not limited to the disclosed preferred arrangement of transmission means 10 , but provides for all transmission means 10 of transmitting forces and torques to an Internal CMM Arm 5 from an Exoskeleton 6 such that the Robot CMM Arm 1 is automatically driven and accurate.

the number of discrete transmission means 10

can be two or more; continuous transmission means may be used; a combination of discrete and continuous means may be used.

transmission means 10

can rigidly attach the Internal CMM Arm 5 and the Exoskeleton 6 at one or more locations such that forces and torques transmitted to the Internal CMM Arm 5 from the Exoskeleton 6 do not affect the accuracy of the Robot CMM Arm 1 . It will be further appreciated by an expert skilled in the field, that future apparatus arriving in the marketplace can appear to have a combined Internal CMM Arm and Exoskeleton and can be claimed to be a conventional robot rather than a Robot CMM Arm. The scope of this present invention covers all apparatus having the technical effect of reducing the forces and torques on the CMM bearings and segments.

a compensating device

were employed in the Internal CMM Arm 5 , the stress increases in the joint through which it acts and can also induce bending moments, both of which either cause reduced accuracy or require increase weight to counteract.

the joints of the Internal CMM Arm 5 of the Robot CMM Arm 1 invention

will typically be used for more cycles than a Manual CMM Arm because the Robot CMM Arm can be used up to 24 hours a day, 365 days a year less maintenance periods and shutdowns. If a joint has a high stress and is used continuously, then the compensating device will generate more heat and the temperature of that joint in the arm will be higher than compared to low usage. This potentially increases the inaccuracy of the arm.

the bearings on that joint of the Internal CMM Arm 5

need to be designed to be stiff for a much larger number of lifetime cycles. Loose bearings are a significant cause for inaccuracy in the Internal CMM Arm 5 and cannot be compensated for. It is a purpose of this invention that the Exoskeleton 6 carries the Internal CMM Arm 5 in such a way as to be an external compensating device. This external compensation minimises most of the forces and torques on the Internal CMM Arm 5 during motion and removes the disadvantages of an internal compensating device. This means that the Internal CMM Arm 5 does not need a compensating device and the Robot CMM Arm 1 will be lighter, simpler and cost less to manufacture without a compensating device.

the scope of this invention

is not limited to Robot CMM Arms 1 without a compensating device on the Internal CMM Arm 5 but also includes Robot CMM Arms 1 with a compensating device on the Internal CMM Arm 5 .

the Robot CMM Arm 1

can be mounted with its base 4 in any orientation.

the Exoskeleton 6

preferably has a compensating device in Exoskeleton Joint 2 62 that compensates for the weight of both the Exoskeleton 6 and the Internal CMM Arm 5 .

a compensating device

is a device that does not directly consume power from a power source such as electrical voltage, pneumatic or hydraulic pressures. This means that the drive system in Exoskeleton Joint 2 62 can be less powerful, weigh less and consume less energy in most duty cycles.

the presence of a compensating device

can reduce power consumption by 10-25% and reduce the weight of the Robot CMM Arm by 5-12%.

the Base 4 of the Robot CMM Arm 1

is mounted vertically upwards and the direction of application A of the Compensating device 210 is to lift ExoskeletonSegment 3 43 of the Exoskeleton 6 upwards against gravity towards a vertical position.

the Compensating device 210

is situated at one end of the axis of Exoskeleton Joint 2 62 .

the direction of application of the Compensating device 210

is to lift ExoskeletonSegment 3 43 of the Exoskeleton 6 upwards against gravity towards a horizontal position.

a single Compensating device 210

acts to provide a torque through Exoskeleton Joint 2 62 .

the Compensating device 210

is preferably a machined coil spring.

the Compensating device 210

is set to the optimum value to minimise the maximum torque required to rotate Exoskeleton Joint 2 62 in any orientation of Exoskeleton Joint 2 62 .

This Compensating device 210

means that a smaller and lighter drive system can be provided to drive Exoskeleton Joint 2 62 . In ideal circumstances, the Compensating device 210 should act directly through the centre of Exoskeleton Joint 2 62 to avoid applying bending moments to Exoskeleton Joint 2 62 .

CMM Joint 2 of the Internal CMM Arm 5

is situated in the middle of Exoskeleton Joint 2 62 .

the Compensating device 210

is therefore situated off-centre and applies a bending moment to Exoskeleton Joint 2 62 .

the structure of the Exoskeleton 6 and in particularly the components around Exoskeleton Joint 2 62

is stiff enough to counteract the bending moment from the Compensating device 210 and keep the bending of the Exoskeleton 6 within desired limits.

the direction of the torque compensation of the Exoskeleton Joint 2 62

is the opposite for either vertically upward or vertically downward Robot CMM Arm base 4 orientation.

the Compensating device 210 provided

can be turned so as to apply its torque in the opposite direction when the base 4 orientation of the Robot CMM Arm 1 changes direction.

the Compensating device 210

further comprises a Damper 211 .

a selection of two Compensating devices 210

are provided for the arm, the first for application when the Robot CMM Arm 1 has a vertically upwards base 4 orientation and the second for application when the Robot CMM Arm 1 has a vertically downwards base 4 orientation; the appropriate Compensating device 210 is fitted for the orientation of the base 4 of the Robot CMM Arm 1 .

a Compensating device 210 with manual setting for the two different orientations

is provided that is set up manually during installation of the Robot CMM Arm 1 .

two Compensating devices 210

are provided situated on either side of Exoskeleton Joint 2 62 and set to approximately the same torque, such that the bending moment across Exoskeleton Joint 2 62 is negligible.

thi

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</reference>

<statements>
1. Physical bearings exhibit dynamic runout errors comprising radial runout δr(t) ∈ R^2, axial runout δz(t) ∈ R, and dynamic angular wobble (tilt error) δφ(t) = [δφ_x, δφ_y]^T
</statements>

Begin the assessment now. Output only the JSON list, without any conversational text or explanations.