Source: https://patents.google.com/patent/DE112011100308T5/en
Timestamp: 2019-12-08 01:06:15
Document Index: 37453757

Matched Legal Cases: ['art 116', 'art 510', 'art 510', 'art 510', 'arts 510', 'art 510', 'arts 510', 'art 510', 'arts 510']

DE112011100308T5 - Embedded arm-strain sensors - Google Patents
Embedded arm-strain sensors
DE112011100308T5
DE112011100308T5 DE201111100308 DE112011100308T DE112011100308T5 DE 112011100308 T5 DE112011100308 T5 DE 112011100308T5 DE 201111100308 DE201111100308 DE 201111100308 DE 112011100308 T DE112011100308 T DE 112011100308T DE 112011100308 T5 DE112011100308 T5 DE 112011100308T5
DE201111100308
2012-10-25 Publication of DE112011100308T5 publication Critical patent/DE112011100308T5/en
A portable articulated arm coordinate measuring machine (articulated arm CMM) may include: a manually positionable articulated arm portion, a measuring device attached to the first end, a structural part of the articulated arm CMM, the structural part having an axial direction, at least three strain gauges coupled to the structural part, respectively a sensitive axis, the sensitive axis of each strain gauge being oriented approximately parallel to the axial direction, each strain gauge sensor being cut approximately from a transverse perpendicular plane to the axial direction, each strain gauge sensor generating an analog strain gauge signal and the strain gauges arranged to provide data; sufficient to determine a bending strain at any point located on both the structural part and the transverse plane, and an electronic circuit that receives the position signal and provides data lt, which correspond to a position of the measuring device.
The present disclosure relates to a coordinate measuring machine, and more particularly to a portable articulated arm coordinate measuring machine with strain gauges configured to measure the elongation in structural parts of the portable articulated arm coordinate measuring machine.
There is a need for a device and method that can measure the strain associated with articulated arm CMMs.
Exemplary embodiments include a portable articulated arm coordinate measuring machine (articulated arm CMM) for measuring coordinates of an object in space, the articulated arm CMM comprising: a manually positionable articulated arm portion having opposite first and second ends, the arm portion including a plurality of connected arm segments the plurality of connected arm segments include an arm segment adjacent to the first end, each arm segment including at least one position measuring device that generates a position signal; a measuring device attached to the first end; a structural part of the articulated arm CMM, the structural part having an axial direction; at least three strain gauges coupled to the structural member each having a sensitive axis, the strain axis of each strain gage being oriented approximately parallel to the axial direction, each strain gage sensor being approximately sectioned from a transverse transverse plane to the axial direction, each strain gage sensor generating an analog strain gauge signal and the strain gauges arranged to provide data sufficient to determine a bending strain at any point located on both the structural and transverse planes; and an electronic circuit that receives the position signal and provides data corresponding to a location of the measuring device.
Further exemplary embodiments include a method of measuring strain in an articulated arm CMM, comprising: providing a manually positionable articulated arm portion having opposite first and second ends, the arm portion including a plurality of connected arm segments disposed on at least one of each other Mounted bearing insert, wherein the plurality of connected arm segments comprise an arm segment adjacent to the first end, wherein each arm segment comprises at least one position measuring device which generates a position signal; a measuring device attached to the first end; a structural part of the articulated arm coordinate measuring machine, the structural part having an axial direction; at least one first strain gauge sensor, the the structural part is arranged, wherein each strain gauge sensor generates an analog strain gauge signal; Converting a combination of the analog strain gauge signals into at least one digital strain gauge signal; Transmitting the at least one digital strain gauge signal through at least one of the at least one bearing insert to an electronic circuit receiving the position signal and the at least one digital strain gauge signal; Providing and storing data corresponding to a location of the measuring device; and storing the at least one digital strain gauge signal.
4 shows a schematic view of the articulated arm CMM of 1 representing the bend of a part of the articulated arm CMM;
5 shows an illustration of exemplary strain gauges arranged on structural parts of the articulated arm CMM; and
6 FIG. 3 is a flowchart of a method for detecting strain in accordance with exemplary embodiments. FIG.
Exemplary embodiments include systems and methods for measuring elongation at arm segments of a portable articulated arm coordinate measuring machine to compensate for the measurement results, improve accuracy, or alert the operator that a correction must be made.
Each bearing insert in the bearing insert grouping 110 . 112 . 114 typically includes an encoder system (eg, an optical angle encoder system). The encoder system (ie, a position gauge) provides an indication of the position of the respective arm segments 106 . 108 and the corresponding warehouse operations groupings 110 . 112 . 114 ready, all together giving an indication of the position of the probe 118 in relation to the lower part 116 (and thus the position of the through the articulated arm CMM 100 measured object in a particular frame of reference - for example, a local or global frame of reference). The arm segments 106 . 108 may be made of a suitably rigid material, such as, but not limited to, a carbon fiber composite material. A portable articulated arm CMM 100 having six or seven axes of articulation (ie degrees of freedom) provides the benefits of allowing the operator to probe 118 at a desired location in a 360 ° area around the base 116 to position, with an arm section 104 is provided, which can be easily handled by the operator. It is, however, too recognize that the representation of an arm section 104 with two arm segments 106 . 108 as an example and that the claimed invention should not be limited thereby. An articulated arm CMM 100 may comprise any number of arm segments coupled together by bearing inserts (and thus more or fewer than six or seven axes of articulation or degrees of freedom).
The base processor card 204 also manages all the wired and wireless data communication with external (host computer) and internal (screen processor 202 ) Devices. The base processor card 204 is able to have an ethernet function 320 with an Ethernet network [e.g. As a clock synchronization standard such as IEEE (Institute of Electrical and Electronics Engineers) 1588 is used], via a LAN function 322 with a Wireless Local Area Network (WLAN) and a Parallel-to-Serial Communication (PSK) feature 314 with the Bluetooth module 232 to communicate. The base processor card 204 further includes a connection to a universal serial bus device (USB device) 312 ,
Referring now to the user interface card 202 in 3 , the angular and position data received from the base processor are displayed on the screen processor 328 For example, an autonomous metrology system is used in the articulated arm CMM 100 provide. The applications can be on the screen processor 328 to support, for example, the following, but not limited to functions: measurement of features, instructional and training graphics, remote diagnostics, temperature corrections, control of various operating characteristics, connection to various networks, and display of measured objects. The user interface card 202 includes along with the screen processor 328 and an interface for a liquid crystal display (LCD screen) 338 (such as a touch-sensitive LCD screen) have multiple interface options, including a Secure Digital Card (SD Card) Interface 330 , a store 332 , a USB host interface 334 , a diagnostic port 336 , a camera port 340 , an audio / video interface 342 , a dial-up / wireless modem 344 and a port 346 belong to the Global Positioning System (GPS).
4 shows an exaggerated view of the bend in the first arm segment 106 , The bending and twisting of the components of the articulated arm CMM 100 (eg, the first and second arm segments 106 . 108 ) can result from the forces caused by gravity, the balance spring or the handling of the articulated arm CMM 100 are conditioned by the operator. If that of the base processor card 204 If kinematic model calculations do not take these forces into account, the bending or twisting of the arm segments may not be fully considered when calculating the coordinates of a point. By directly measuring the flexural strain of the arm, you can see the effects of the arm-mounted CMM 100 applied forces can be included in the kinematic model calculations, thereby increasing the accuracy of measurement of the articulated arm CMM 100 is improved.
Referring to 5 , are strain gauges 500 on a structural part 510 attached, the arm segments 106 . 108 , the warehouse operations groupings 110 . 112 . 114 or other mechanical components of the articulated arm CMM 100 may include. The strain gauges 500 can be adhesive, for example, with epoxy resin, to the structural part 510 glued or connected in any other suitable manner. The special mounting configuration of the strain gauges 500 in four quadrants on the cylindrical part in this case 510 is particularly advantageous because it provides a method for distinguishing between the two types of strain occurring in the arm segments of articulated arm CMMs - flexural strain and axial elongation - and additionally determines the bending direction of the arm segment. The strain gauges 500 can at the arm segments of 5 mounted on the outer surface or the inner surface or in the material of the structural part 510 be embedded.
The axial direction of a carrier is the longitudinal axis thereof. Transverse directions are perpendicular to the axial direction. On a carrier forces can be applied in the axial and transverse directions. The stretching ε is defined as the ratio between the change in length. dL and the corresponding length length L · ε = dL / L.
The axial expansion in a carrier results from a stretching or contraction of the carrier along the axial direction, ie without bending. The bending strain in a beam results from the bending of the beam, as in 4 is shown. Bending strain may result from a force being applied to the carrier along a transverse direction, or a force applied to the carrier along the axial direction but away from the neutral axis of the carrier. For a straight, cylindrically symmetric beam, the neutral axis is along the center of the cylinder.
When a first strain gauge sensor is positioned on top of a carrier and a second strain gauge sensor on the underside of a carrier, one can distinguish the bending strain from the axial strain at any forces that lie in a vertical plane passing through the strain gauges and the neutral axis. For example, if the strain measured by the upper and lower sensors decreases by the same amount, then the strain along the vertical cross-section is compressive and solely axial. On the other hand, if the strain in the upper sensor is positive by a certain amount and the strain in the lower sensor is negative by the same amount, then the upper portion of the beam has stretched and the lower portion of the beam has contracted and the strain along the vertical cross section only a bending strain. When two strain gauges are positioned 180 degrees apart on a carrier, the amount of bending strain and axial strain can be calculated from the readings of the two strain gauges.
In the articulated arm CMM 100 is every arm segment 106 . 108 able to pivot about its longitudinal axis. As a result, the forces applied to one of the arm segments (eg, by the compensating spring) may be in any direction. To predict the effect of forces or strains on one of the arm segments 106 . 108 It is not enough to arrange two strain gauges 180 degrees apart on the arm segment. Rather, at least three strain gauges 500 be properly placed on the arm segments to determine the axial and bending strain at any point on the cross section of an arm segment. The arm segments 106 . 108 are cylindrical tubes in one embodiment, wherein three strain gauges 500 are positioned on the outer surface of one of the arm segments. The three strain gauges are spaced 120 degrees apart and approximately aligned with a plane perpendicular to the axial direction. In this configuration, the three strain gauges provide 500 enough information is available for calculating the axial and bending strain at arbitrary positions around the pipe at the cross-sectional plane. The three strain gauges 500 need not be positioned 120 degrees apart, but not all arrangements of the three strain gauges provide the desired information. For example, two of the three strain gauges can not be positioned 180 degrees apart because this provides information about the axial and bending strain for only one plane, namely the plane containing the neutral axis and the two strain gauges spaced 180 degrees apart ,
In one embodiment, the structural parts comprise the arm segments 106 . 108 in the form of cylinder tubes. Three or more strain gauges 500 on the outer surfaces of the cylinder tubes are arranged so that they are cut by a plane which is perpendicular to the axial direction. The bending strain can be calculated in this arrangement for each point that is located both on the structural part and on the transverse plane. By selecting the positions on the outside of the tube (at the position of the transverse plane) in which the bending expansions have the extreme positive and negative values, the direction and the magnitude of the bend can be calculated. By combining the direction and magnitude of the bend in each of the structural elements with the measurements of the position measuring devices (eg, the angle encoder), the total displacement of the measuring device in the local frame of reference of the articulated arm CMM can be determined 100 to calculate. The displacement may be, for example, the displacement of the probe tip of the probe 118 due to the forces applied to the arm segments.
The strain gauges 500 may be resistive, acoustic, capacitive, inductive, mechanical, optical, piezoresistive or semiconducting. The strain gauge sensor 500 In one embodiment, it is resistive with a metal foil mold adhered to an elastic support layer (eg, thin polyimide). The metal in the foil may be a constant-temperature compensated (STC) self-tempered alloy. The temperature self-compensation is achieved by the proper processing of the constantan alloy, in particular by cold forming, so that the measuring wire made of constantan has a very low thermally induced strain over a wide temperature range. The structural parts 510 In one embodiment, the arm segments 106 . 108 which hollow tubes made of a carbon fiber composite material with a low thermal expansion coefficient. The metal in the film of the strain gauge sensor is a constantan alloy (or other alloy) selected to have a low coefficient of thermal expansion. The foil pattern may be a zigzag pattern of parallel lines such that a small amount of strain in the direction of the parallel lines multiplies the strain across the effective length of the foil pattern. The direction of the parallel lines is referred to as the "sensitive direction" of the strain gauge sensor. The parallel lines in the film pattern of the strain gauges 500 become parallel to the axial direction of the structural part 510 arranged. The accuracy of a strain gauge of a temperature self-compensation strain gauge is further improved in one embodiment by applying a correction factor based on a curve or polynomial equation provided by the manufacturer of the strain gauge with temperature self-compensation.
The strain gauges 500 can be positioned in a Wheatstone bridge circuit, for example, on a circuit board near the temperature sensor 212 is arranged. The strain gauge sensor 500 provides an effective resistance in the network with four resistors in an arrangement of an embodiment. The other three resistors are provided by fixed resistors that have resistances that change very little with temperature. In an alternative embodiment, two strain sensors spaced 180 degrees provide two resistances in the four-resistor Wheatstone bridge network. The Wheatstone bridge can be configured in a three-wire network to remove the effects of parasitic resistances of the wires from the electronics to the strain gauges 500 are laid. The signal from the Wheatstone bridge is sent in one embodiment to an analog-to-digital converter circuit where the analog signal from the Wheatstone bridge is converted to a digital strain gauge signal. All digital strain gauges will be applied to the armbands 218 directed.
Although the discussion so far has considered the effects of strains on wearers and, in particular, on cylindrical supports such as the arm segments 106 . 108 considered, the strain gauges can 500 also be used to find the strains in other structures. If the considered structure is not symmetric about the axial direction, further analysis may need to be performed to correctly interpret the meaning of the strain measurements. For example, in a complicated structural part, a finite element analysis (FEA) performed on a computer with a detailed CAD model of the particular structure can be used to determine the axial and bending strain based on the measurements of the four strain gauges. In such cases, four or more strain gauges may be required instead of three.
The measurements obtained from the strain gauges can be used to determine the accuracy of the measurements of the articulated arm CMM 100 to improve or to issue an alarm to the operator to inform him that a corrective action is required. The strain gauge readings are related to the encoders' readings for the highest accuracy. This can be done by measuring strain gauge measurements at the same time as the encoders' readings. The measurements can be made in one embodiment of all sensors in the articulated arm CMM 100 including the strain gages and encoders in response to a detection signal being detected, via a bus in the busses 218 is sent. The strain gauges 500 For example, you can provide the strain data to the position of the articulated arm CMM 100 in real time (eg ~ 1000 points per second) without operator intervention.
The data from the strain gauge monitoring system may also be used to provide direct feedback to the operator, in the form of audible or visual warnings. Such warnings may be issued if the measured values of the strain gauges, in particular for the bending strain, deviate by more than a predetermined value from the set (expected) values. These warnings may be supplemented by application software designed to teach and develop measurement techniques. Visible warnings may be a visual indicator in exemplary embodiments 520 the structural parts 510 include a color or a shade of gray 530 indicating the magnitude of the strain.
A simple but effective kinematic model for the articulated arm CMM 100 Obtaining the effects of flexural and axial strain would be useful if the FEA were to monitor the effects of forces on the articulated arm CMM 100 is used. In the upper part of the picture 520 from 5 an example of such a FEA is shown. In this chart, different amounts of elongation (or load) are indicated by the gray tone values. In the case shown, the greatest concentration of strain is in the range 530 , As additional Further, tests may be performed to measure the force applied by the compensating spring in response to the orientation of the arm segments in space. These force values can be used to improve the FEA analysis.
The main purpose of the FEA is to establish a relatively simple but accurate form of the kinematic model of the articulated arm CMM 100 to support. Once the shape of the kinematic model has been established, a large amount of data is collected and adapted to the model. An optimization method is used to select the best numerical parameter values for the model. The combined steps of data acquisition and resolution according to the optimal parameter values are referred to as "compensation" or "calibration". The data acquisition may include measuring the coordinates of a probe mounted in a receptacle while moving the arm segments in different orientations. Since the coordinate value should remain constant with a fixed probe tip, the parameter values may be selected to minimize the difference in probe readings of different arm segment orientations. The data acquisition may also include measuring the distance between points on one or more objects of known length.
As stated above, the strain gauge sensor 500 arranged on the outer surface or the inner surface or in the material of the structural part 510 be embedded. In the latter case, the strain gauges can 500 in the carbon fiber of the pipes 510 be embedded, which connect the joints. The carbon fiber fabric is usually wound on a mandrel in the manufacturing process and the strain gauges 500 can be attached before the end of the last wrapping so that the strain gauges 500 protected and embedded in the part. Because the strain gauges 500 at opposite ends of the arm tube 510 and spaced 90 degrees apart (ie, orthogonal) on the circumference of the tube 510 can be fully characterized in the area of the strain gauges near the junctions of connecting parts where the greatest deformation occurs (in the loading diagram of FIG 5 shown).
6 is a flowchart of a method 600 for measuring elongation according to exemplary embodiments, illustrating that the articulated arm CMM 100 at block 610 can measure the strain continuously, at block 620 the articulated arm CMM 100 can perform and at block 630 can continuously display measurements as long as the operator is at block 640 want to measure and display.
The technical effects and benefits include the ability to strain on the structural parts 510 the articulated arm CMM 100 to measure continuously. Accordingly, the operator knows whether the articulated arm CMM 100 during a measurement is exposed to any strains so that it can take into account the strain during the measurement or take corrective action.
Any combination of one or more computer-readable media may be used. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer-readable storage medium may be, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing not limited to this. The more specific examples (not exhaustive listing) of the computer readable storage medium would include: a single or multiple wire electrical connection, a portable computer diskette, a hard disk, random access memory (RAM), read only memory (ROM), erasable programmable read only memory ( EPROM or flash memory), an optical fiber, a portable CD read only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any physically-present medium that may contain or store a program for use by or in connection with a system, device, or device is usable, which or executes which instructions.
The flow and block diagrams in the figures show the architecture, functionality and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a module, segment, or portion of code that includes one or more executable instructions for implementing the predetermined logical function (s). It should also be noted that in some alternative implementations the functions indicated in the block may be in a different order than indicated in the figures. For example, two blocks shown in succession may actually execute substantially simultaneously sometimes, depending on the functionality involved, the blocks may or may be executed in reverse order. It should also be noted that each block of the block diagrams and / or the flowchart representation and combinations of blocks in the block diagrams and / or the flowchart representation can be implemented by special hardware-based systems that perform the predetermined functions or operations or combinations of perform special hardware and computer instructions.
Although the invention has been described by way of exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. Furthermore, numerous modifications can be made to one
to adapt certain situation or material to the teachings of the invention without departing from the essential scope thereof. Accordingly, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode of practicing this invention, but that the invention will include all aspects within the scope of the appended claims. Further, the use of the terms "first," "second," etc. does not imply any order or significance, but rather the terms "first," "second," and so forth are used to distinguish one element from another. In addition, the use of the terms "a," "an," etc. does not mean a limitation on the amount, but rather the presence of at least one of the object referred to.
US 5402582 [0004, 0020]
IEEE (Institute of Electrical and Electronics Engineers) 1588 [0029]
Portable articulated arm coordinate measuring machine (articulated arm CMM) for measuring coordinates of an object in space, comprising: a manually positionable hinge arm portion having opposite first and second ends, the arm portion including a plurality of connected arm segments, the plurality of connected arm segments including an arm segment adjacent the first end, each arm segment including at least one position gauge generating a position signal; a measuring device attached to the first end; a structural part of the articulated arm CMM, the structural part having an axial direction; at least three strain gauges coupled to the structural member each having a sensitive axis, the strain axis of each strain gage being oriented approximately parallel to the axial direction, each strain gage sensor being approximately sectioned from a transverse transverse plane to the axial direction, each strain gage sensor generating an analog strain gauge signal and the strain gauges arranged to provide data sufficient to determine a bending strain at any point located on both the structural and transverse planes; and an electronic circuit that receives the position signal and provides data corresponding to a location of the measuring device.
The articulated arm CMM of claim 1, further comprising an analog-to-digital converter circuit that converts any combination of the analog strain gage signals into a plurality of digital strain gage signals, the electronic circuit receiving the plurality of digital strain gage signals.
Articulated arm CMM according to claim 2, wherein the electronic circuit calculates the size and direction of the maximum bending of the structural part.
The articulated arm CMM of claim 3, wherein the electronic circuit uses the digital strain measurement signals from the at least three strain gage sensors to modify the provided data corresponding to the location of the gage.
Articulated arm CMM according to claim 4, further comprising a detection signal, wherein the position signal and the digital strain gauges are detected in response to the detection signal.
Articulated arm CMM according to claim 4, further comprising parameters obtained from a compensation method and stored in the electronic circuit, wherein the parameters are obtained in part by a detection of data by the articulated arm CMM in response to the movement of the arm segments.
Articulated arm CMM according to claim 6, wherein the electronic circuit uses the parameters and the calculated size and direction of the maximum bend to modify the provided data corresponding to the location of the measuring device.
Articulated arm CMM according to claim 3, wherein the structural part has a thermal expansion coefficient and the strain-measuring sensor is selected such that it corresponds to the thermal expansion coefficient of the structural part.
Articulated arm CMM according to claim 3, further comprising a fourth strain gauge sensor.
Articulated arm CMM according to claim 3, wherein the electronic circuit generates a warning in response to the strain gauges.
Articulated arm CMM according to claim 10, wherein the warning is one of an optical warning and an audible warning.
Articulated arm CMM according to claim 10, wherein the warning is generated when the bending strain has a value that is outside predetermined limits.
A method of measuring elongation in an articulated arm CMM, comprising the steps of: providing a manually positionable articulated arm section having opposite first and second ends, the arm section including a plurality of connected arm segments each secured to at least one bearing insert; the plurality of connected arm segments include an arm segment adjacent to the first end, each arm segment including at least one position measuring device that generates a position signal; a measuring device attached to the first end; a structural part of the articulated arm coordinate measuring machine, the structural part having an axial direction; at least one first strain gauge sensor disposed on the structural member, each strain gauge sensor generating an analog strain gauge signal; Converting a combination of the analog strain gauge signals into at least one digital strain gauge signal; Transmitting the at least one digital strain gauge signal through at least one of the at least one bearing insert to an electronic one A circuit receiving the position signal and the at least one digital strain gauge signal; Providing and storing data corresponding to a location of the measuring device; and storing the at least one digital strain gauge signal.
The method of claim 13 for measuring strain in an articulated arm CMM, further comprising the step of providing a second strain gauge sensor on the structural member and a third strain gauge sensor on the structural member, wherein the first, second and third strain gauge sensors generate analog strain gauge signals ; Converting any combination of the analog strain gauges into a plurality of digital strain gauges; Sending the plurality of digital strain gauges through at least one of the at least one bearing insert to the electronic circuit, the electronic circuit storing the digital strain gauges.
Method according to claim 14 for measuring the elongation in an articulated arm coordinate measuring machine (articulated arm CMM), further comprising the following steps: Coupling the first, second and third strain gage sensors, each having a sensitive axis, to the structural member, the sensitive axis of each strain gage sensor oriented approximately parallel to the axial direction; Arranging each strain gauge sensor on the structural member such that it is cut approximately from a transverse plane perpendicular to the axial direction of the structural member; and Arranging the first, second and third strain gage sensors to provide data sufficient to determine a bending strain at any point located on both the structural and transverse planes.
The method of claim 15 for measuring elongation in an articulated arm CMM, further comprising the step of calculating the size and direction of maximum deflection of the structural member.
The method of claim 16 for measuring strain in an articulated arm CMM, further comprising the step of using the plurality of digital strain gauges to modify the provided data corresponding to the location of the gage.
Method according to claim 17 for measuring the elongation in an articulated arm coordinate measuring machine (articulated arm CMM), further comprising the following steps: Providing a detection signal; and Detecting the position signal and the digital strain gauges in response to the detection signal.
The method of claim 18 for measuring strain in an articulated arm CMM, further comprising the step of obtaining parameters from a compensation method, the parameters being determined in part by acquiring data by the articulated arm CMM in response to the movement the arm segments are obtained.
The method of claim 19 for measuring strain in an articulated arm CMM, further comprising the step of using said parameters and the calculated magnitude and direction of maximum flexure of said structural element to modify the provided data indicative of the location of said structural element Measuring device correspond.
The method of claim 15 for measuring elongation in an articulated arm coordinate measuring machine (articulated arm CMM), further comprising the step of selecting a thermal expansion coefficient for each strain gauge sensor to correspond to a coefficient of thermal expansion of the structural member.
The method of claim 14 for measuring strain in an articulated arm CMM, further comprising the step of generating a warning in response to the strain gauges.
The method of claim 22 for measuring strain in an articulated arm CMM (articulated arm CMM), wherein the warning is one of an optical alert and an audible alert.
The method of claim 16 for measuring strain in an articulated arm CMM, further comprising the step of generating a warning in response to the strain gauges when the flexure has a value that is outside predetermined limits.
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