WO2013044677A1

WO2013044677A1 - Large-scale, three-dimensional coordinate measuring method and apparatus with laser tracking

Info

Publication number: WO2013044677A1
Application number: PCT/CN2012/079264
Authority: WO
Inventors: 裘祖荣; 张国雄; 李杏华; 刘书桂; 郭敬滨
Original assignee: 天津大学
Priority date: 2011-09-29
Filing date: 2012-07-27
Publication date: 2013-04-04
Also published as: CN102506702B; CN102506702A

Abstract

Disclosed are a large-scale, three-dimensional coordinate measuring system with laser tracking and a large-scale, three-dimensional coordinate measuring apparatus with laser tracking, composed of three parts, namely a measuring machine, a laser tracker and a computer control system, and a laser interferometer measuring line displacement, wherein the measuring machine is provided with a horizontal arm (5) able to move in the direction X, and a main shaft (8) able to move in the direction Z; a corner prism (4) is mounted on the other end of the horizontal arm (5); a measuring head rotating body (11) is provided on one end of the main shaft (8); a measuring head (10) is provided on the measuring head rotating body (11); a target (6) and an angle measuring means (7) are provided on the other end of the main shaft (8); and a temperature measuring element is attached on the main shaft (8) for temperature compensation. The invention is mainly applicable to three-dimensional coordinate measurement.

Description

Large-scale three-coordinate measuring method and device with laser tracking

The invention relates to spatial coordinate measurement of large-scale engineering and large machines and workpieces, and can be used in engineering, machine operation, parts processing and assembly field. The size of the object to be tested can be much larger than the size of the testing equipment, and the measurement precision is high, which belongs to testing technology. And the field of instruments, involving the measurement of three-dimensional coordinates of large-scale space. Specifically, it relates to large-scale three-coordinate measuring methods and devices with laser tracking. Background technique

With the development of high technology, large-scale engineering, large-scale machines, and large-scale parts are increasingly used in national economy and national defense, and their accuracy requirements are getting higher and higher. High-precision inspection of large engineering objects, especially on-site inspection, is a problem that is not well solved worldwide.

The most widely used geometric coordinate coordinate detection is the orthogonal coordinate measuring machine, but the orthogonal three-coordinate measuring machine cannot meet the requirements of high-precision detection of large engineering objects in many aspects. The first thing to measure, the larger the workpiece, the larger the CMM. This CMM is not only expensive, but also technically difficult. In order to obtain an open measurement space, a gantry structure is generally used, as shown in Fig. 1. From the structural form, the scale and drive can only be on the side. Not only will it bring a large Abbe arm and swing around the Z axis, resulting in a large Abbe error, and the drive is not easy to stabilize. In order to improve the driving performance of the measuring machine and reduce the Abbe error, a dual-drive and double-scale solution is often used for a measuring machine with a 7-direction stroke of 2 m or more. The signal fed back by the double ruler controls the synchronous movement of the left and right sides, which is technically difficult. The manufacture of long rails is also very difficult. At present, the world's largest measuring machine has a stroke of 20m and the price is millions of dollars. More importantly, this CMM cannot be used in the field, but it is necessary to move the object to the CMM. This is not possible in many cases.

In order to meet the needs of on-site measurement, the theodolite shown in Figure 2 is a commonly used instrument. Using two or more theodolites to aim at the same target point P, each theodolite measures two angles, one is the horizontal azimuth angle, and the other is the angle on the vertical plane. The P point can be obtained by triangulation. Coordinates in three-dimensional space. The disadvantage of this method is that in order to obtain the coordinates of the P-point, the distance b and the height difference h of the optical centers of the two theodolites must be known, which requires calibration with a long gauge or other standard specimen. Long gauge or standard specimens are difficult to manufacture, inconvenient to use, and the accuracy is difficult to guarantee. In addition, the measurement of large size by the theodolite is based on the principle of triangulation angle measurement, and the uncertainty of the measurement angle increases with the increase of the distance. The line displacement or size is also multiplied by the distance to further increase the measurement uncertainty. More importantly, the theodolite is difficult to measure the internal parameters of the object. Fig. 3 is a principle of measuring a large size by using a multi-camera, and the same point P is simultaneously imaged in a plurality of cameras, and the spatial coordinates of the P point can be determined by data processing. The multi-camera system, like the theodolite system, is based on the principle of triangulation angle measurement, which requires calibration with a long standard rule or standard sample. The measurement uncertainty increases rapidly with increasing distance and is difficult to measure the internal parameters of the object.

Figure 4a shows the laser tracker, which uses the spherical coordinate measurement principle shown in Figure 4b. The target shown in Figure 5 is used for the measurement, and the target moves along the surface to be measured. When the target center 0 deviates from the incident beam emitted by the laser tracker, the outgoing beam reflected by the target does not return along the original path, but is staggered by a distance, as shown in Fig. 5. The laser tracker picks up this information, tracks it, and changes the direction of the beam until the incident beam from the laser tracker passes through the center of the target. Thus, the position of the target point Pi can be determined according to the angle Φ ί, 9 i of the laser tracker about the horizontal and vertical axis and the distance Li from the origin of the interferometer to the target center 0 measured by the interferometer inside the laser tracker ( Figure 4b). The laser tracker has high precision and a large measuring range (tens of meters). The main disadvantage is that it is difficult to measure the internal characteristics of the object under test. It is true that manufacturers of laser trackers have also introduced hand-held light pens (Fig. 6), one end of which is a probe (or rigid probe), the other end is a target, and the laser tracker is aimed at the target for measurement. It allows you to measure certain internal features that are not far from the outline of the object being measured. The main problem is that it is difficult to control the direction of the stylus during manual operation, and the relative position of the probe (or the probe) to the target is unchanged. A slight tilt of the stylus can cause significant errors. For this reason, and for operational reasons, the light pen is usually short and does not exceed 200-300mm.

Summary of the invention

In order to overcome the deficiencies of the prior art, it is provided that it can be used in engineering or production sites, has high measurement accuracy, is safe and reliable in operation, has a large measuring range, can detect internal and external features of the object to be tested, and can satisfy various engineering and production processes. The need for dimensional measurement, a large coordinate measuring system with laser tracking. The technical solution adopted by the invention is a large-scale three-coordinate measuring device with laser tracking, which is composed of a measuring machine, a laser tracker and a calculation control system, and a laser interferometer for measuring line displacement; the measuring machine is provided with: a column and The bottom is provided with wheels for moving the measuring machine to the object to be measured and close to the measured feature point; the horizontal arm mounted on the column can be moved, and the spindle mounted at one end of the horizontal arm can make z direction Movement, the other end of the horizontal arm is equipped with a corner prism; the upper end of the main shaft is equipped with a probe revolving body, and the revolving body of the measuring head can rotate horizontally and vertically; the probe is equipped with a probe on the rotating body, and the probe is equipped with a probe The probe has a strain gauge for measuring the deformation of the probe; the other end of the spindle is equipped with a target and a goniometer, and a temperature measuring component is attached to the spindle for temperature compensation;

The distance between the optical center of the target and the center of the revolving body of the probe is determined;

The laser interferometer is aimed at the corner cube prism at the end of the horizontal arm. The beam of the laser interferometer is adjusted to be parallel to the movement of the horizontal arm. The laser tracker is aimed at the target and the horizontal arm moves in the direction, and the laser interferometer and the laser are recorded. The reading of the tracer, after data processing, can simultaneously determine the distance between the optical center of the laser tracker and the optical center of the target at the calibration initial position, and the spatial relative position between the corner prism and the optical center of the target;

The laser tracker is used to track and measure the position of the optical center point of the target. The angle measuring device is used to measure the deflection angle of the main axis with respect to the object to be measured, and the strain gauge measures the bending deformation of the probe and performs error compensation.

The device is provided with a probe protection mechanism, and the probe protection mechanism is a movable seat. The spring and the positioning mechanism accurately position the movable seat relative to the probe base, and the side head is fixed on the movable seat, and the side head seat is fixed on the probe. On the rotating body, when the probe collides with the workpiece or other object from any direction, the positioning mechanism is disengaged, the contact pair in the positioning mechanism is disconnected, the measuring machine stops moving, and the measuring head and the measuring machine are protected.

The angle measuring device is two electronic level meters, which measure the rotation of the main shaft around the ^ and the axis.

A large three-coordinate measuring method with laser tracking is implemented by means of a large coordinate measuring device with laser tracking and includes the following steps:

1. Install the measuring machine, laser tracker and calculation control system at the measurement site, move the measuring machine to the first position beside the object to be measured according to the measurement needs, and use the line displacement measurement laser interferometer to aim at the angle prism, and The laser beam of the interferometer is adjusted to a direction parallel to the X-direction motion of the horizontal arm of the measuring machine. The absolute distance between the target 6 and the optical center of the laser tracker is calibrated by moving the horizontal arm in the full range of the X direction while recording a series of readings of the line displacement measuring laser interferometer and the laser tracker;

2. Using the measuring machine to measure several points on the object to be measured, and realize the unification of the coordinate system of the laser tracker, the measuring machine and the measured object;

3. Optimization of the measurement scheme and path planning: including the determination of the number of positions and specific positions that the measuring machine needs to move; the path planning and optimization of the horizontal arm, the main shaft, the revolving body of the measuring machine at various positions, anti-collision and anti-laser Tracker lost light inspection; laser tracker needs to move the number of positions and the specific location is determined;

4. In the first position of the laser tracker and measuring machine, automatic measurement is performed. The computer collects and stores the laser tracker readings of each sampling point: including the rotation angle of the two axes around the laser tracker and the measurement by the interferometer. The distance from the optical center of the laser tracker to the optical center of the target, the angle of the spindle of the measuring machine around the X and _y axes measured by the angle measuring device, the temperature of the spindle measured by the temperature measuring element, and the rotation of the probe around its two axes Corner, probe deformation measured by strain gauge, 3D probe reading;

5. After completing all the inspection work at one position of the measuring machine, the above path planning keeps the laser tracker in motion and moves the measuring machine to the next position. In the process of moving the measuring machine, special attention should be paid to prevent the laser tracker from losing light. And on the basis of this, keep the coordinate system one before and after the movement of the measuring machine;

6. According to the path plan determined by the virtual coordinate measuring machine, complete at this position in the new position of the measuring machine All measurement movement, data acquisition and storage;

7. According to the path planning, if necessary, keep the target of the measuring machine, move the laser tracker to the next position, and pay special attention to prevent the laser tracker from losing light when moving the laser tracker. Maintaining a coordinate system before and after the movement of the laser tracker;

8. According to the path plan determined by the virtual coordinate measuring machine, all measurement movements, data acquisition and storage at this position are completed at the new position of the laser tracker;

9. Repeat the above steps as needed until all measurements are completed. The invention has the following technical effects - 1. It can measure various geometric parameters of large workpieces, machines or engineering objects with a size of several tens of meters;

2. The measuring system can be moved and can be measured at the site of the measured object.

3. It can measure the external and internal characteristic parameters of the measured object.

4. The measurement accuracy is high, and there is no strict requirement for the motion accuracy of the measuring machine. The measurement accuracy is mainly guaranteed by laser tracker, error compensation (spindle rotation angle and deformation measurement, probe deformation measurement, etc.), probe and probe revolving body, calibration and so on.

5. The measuring machine works safely and reliably.

6. The cost is much lower than that of a large CMM with the same measurement range and accuracy. DRAWINGS

Figure 1 is a schematic diagram of a large gantry type CMM. In the figure: 10 is the column, 11 is the guide rail, 12 is the beam, 13 is the carriage, and 14 is the main shaft.

Figure 2 is a schematic diagram of the theodolite.

Figure 3 is a schematic diagram of a multi-camera system.

Figure 4 is a schematic diagram of a laser tracker.

Figure 5 is a schematic diagram of the target.

Figure 6 is a schematic diagram of the light pen.

Figure 7 is a schematic diagram of a large three-coordinate measuring system with laser tracking.

Figure 8 is a schematic diagram of a collision protection mechanism. In the figure: 1 is the probe, 2 is the positioning mechanism and the contact pair, 3 is the movable seat, 4 is the spring, and 5 is the probe holder. detailed description

The present invention is directed to the above problems, and an invention (1) can be used at an engineering or production site; (2) high measurement accuracy; (3) safe and reliable; (4) large measurement range; (5) capable of detecting the inside of the object to be tested The external features of the large-scale three-coordinate measuring system with laser tracking can meet the needs of large-scale measurement in various engineering and production.

The large three-coordinate measuring system with laser tracking consists of three parts: measuring machine, laser tracker and calculation control system, as shown in Figure 7. The main function of the measuring machine is to explore the feature points of the measured object, including external feature points and internal feature points. The bottom of the measuring machine's column 3 has a wheel 2, which can be moved to the site of the object to be measured and is closer to the measured feature point. At the arrival position, the pawl 1 is lowered to give the measuring machine a stable position. For easy exploration, the horizontal arm 5 can be moved in the X direction, the main shaft 8 can be moved in the z direction, and the revolving body 11 of the probe can be rotated horizontally and perpendicularly, and the probe 10 detects the position of the measured point.

There is no strict accuracy requirement for the movement, positioning of the entire measuring machine, the movement of the horizontal arm 5, and the z-direction movement of the spindle 8. Instead of determining the coordinate position of the probe point P based on their position, the laser tracker is used to track and aim the target 6 to determine the position of the optical center M point of the target.

The distance between the optical center of the target 6 and the center Q of the probe is determined. The effect of the temperature change on the change in the distance between the M point and the Q point can be compensated by the temperature measuring element attached to the spindle 8. The most serious impact comes from the uncertainty of the spindle 8 direction. The tilt of the entire measuring machine, the angular motion error of the horizontal arm 5, the bending deformation of the horizontal arm 5, and the angular motion error of the spindle 8 all seriously affect the spatial position of the β point with respect to the M point. Since the object to be measured is a large-sized piece, / and /ζ in Fig. 7, the length of the spindle 8 should be large enough so that the probe 10 can detect the measured point to be measured. Therefore, the effects of the above tilting, deformation and motion errors can be quite large, and compensating them will make the whole measurement meaningless. The present invention uses an angle measuring device 7 to measure the deflection angle of the main shaft with respect to the object to be measured and the direction of _y, and introduces error compensation.

In order to facilitate the measurement of internal features, it is necessary to use a probe having a longer length and a smaller diameter. In order to compensate for the influence of the bending deformation of the probe, a strain gauge is attached to the probe 9. The accuracy of the rotation angle of the probe revolving body 11 is quite high. After the error of the deflection of the main shaft 8 and the bending deformation of the probe 9, the spatial position of the detection point P relative to the β point of the center of the revolving body of the probe can be accurately determined.

WoJ uses a laser tracker to accurately measure the position of the optical center point of the target, and uses the angle measuring device 7 to measure the deflection angle of the main shaft 8 with respect to the object to be measured around the X direction, and uses the strain gauge to measure the bending deformation of the probe 9, and performs After the error compensation, the spatial position of each feature point inside or outside the measured object can be accurately measured.

Another important issue in large-scale field measurements is safety and reliability. Since the inside of the object to be measured is invisible, the measuring machine is temporarily pushed to the vicinity of the object to be measured, and it is easy to collide due to improper operation. To ensure safety Reliable operation, the invention adopts anti-collision technology and collision protection technology based on virtual coordinate measuring machine.

In the present invention, the optical center of the laser tracker (the origin of the interferometer) functions as a reference point, and in principle, the position of the laser tracker is required to be fixed throughout the measurement. However, in large-size measurement, because the size of the object to be measured is large, and the measuring machine is not too large, it is necessary to push the measuring machine to each nearby position and measure from different directions. It is possible that the laser beam emitted by the laser tracker is blocked. Case. The present invention has developed a technique for allowing a mobile laser tracker to be moved under the premise of ensuring uniformity of the reference. The laser tracker achieves uniformity by aiming at the same fixed target 6 before and after shifting.

The calculation control system performs tasks such as motion control, measurement data acquisition, error compensation, and data processing. And (6) the new pose parameters of the transmitting station after changing the posture.

The invention proposes a requirement that can be used in engineering or production field, high measurement precision, safe and reliable work, large measuring range, capable of detecting internal and external features of the object to be tested, and capable of meeting large-scale measurement in various engineering and production. Large three-coordinate measuring system with laser tracking.

The invention relates to a large-scale three-coordinate measuring system composed of a movable low-precision coordinate measuring machine, a laser tracker and a calculation control system.

The measuring machine, laser tracker and calculation control system are all movable from the requirements of being able to measure on-site at the object under test.

An important innovation of the present invention is to separate the implementation from the guaranteed measurement accuracy.

In order to achieve on-site measurement and minimize the size of the measuring machine, the measuring machine can be moved to the object to be measured and stopped at the desired position.

In order to be able to detect various internal and external features of the object to be measured, as shown in Figure 7, its horizontal arm 5 can do

In the X-direction movement, the spindle 8 can be moved in the z-direction, and the spindle 8 is provided with the probe revolving body 11 and the probe 10, so that it can easily detect the measured point.

In order to ensure the measurement accuracy, the target 6 is mounted above the main shaft 8, and the target can be a cat's eye or a corner prism. The position of target 6 is accurately determined by a laser tracker. The overall movement of the measuring machine, as well as the upward movement of the horizontal arm 5, and the z-direction motion accuracy of the spindle 8 have substantially no effect on the measurement uncertainty. Their accuracy is as long as they meet the requirements of being able to detect the point to be measured. The spindle 8 is provided with a goniometer 7 for measuring the rotation of the spindle about the X and the shaft, and is attached with a temperature measuring element. With the angle measuring device 7 and the temperature measuring element, the relative position of the center of rotation Q of the probe revolving body 11 with respect to the optical center M of the target 6 can be accurately determined, thereby accurately determining the spatial position of the center of rotation Q of the head revolving body 11. The probe 9 of the probe 10 is provided with a strain gauge which can detect the deformation of the probe due to the measurement force and gravity, and introduces error compensation for the deformation of the probe according to it. Since the above error compensation measures are introduced, the measuring machine can be moved to the corresponding position near the object to be measured as needed, and the deformation of the horizontal arm of the measuring machine and the motion error of the horizontal arm and the vertical spindle do not affect the measurement accuracy, and can be reduced. The small measuring machine is small in size, reduces the manufacturing precision requirements of the measuring machine, uses long horizontal arms and spindles, and goes deep into the various parts of the object to be measured, while maintaining high measurement accuracy.

In order to achieve safe and reliable automatic measurement, a virtual coordinate measuring machine is used to model the measuring machine and the measured object. After manually detecting several points on the object to be measured, the conversion and unification between the laser tracker coordinate system and the coordinate system of the object to be measured (workpiece coordinate system) can be realized. It can be realized on the virtual coordinate measuring machine: (1) It is determined that the three coordinate measuring machine needs to move several positions and move to which positions to complete the measurement of all the elements to be tested of the measured object. The overall position of the measuring machine is optimized. (2) Determine if the laser tracker's beam is able to detect the target 6 unobstructed for these positions of the CMM. In the case of difficulty, determine where the laser tracker needs to be moved, and the beam of the laser tracker can unimpededly target the target 6 . Optimize the movement position of the laser tracker. (3) The measurement path planning of the measuring machine is carried out, including the movement of the horizontal arm 5, the movement of the main shaft 8 and the rotation of the probe revolving body 11, and the collision prevention inspection is performed. Optimize the measurement path planning of the measuring machine. (4) Under the control of the computer, the automatic measurement of the measured object is realized according to the optimized path planning.

Based on the established measuring machine model, the position of the target center M measured by the laser tracker, the spindle 8 measured by the angle measuring device 7 around the X and y axis, the spindle temperature measured by the temperature measuring element, the probe revolving body 11 The angle around the horizontal and vertical axis, the deformation of the probe 9 measured by the strain gauge, and the reading of the probe 10 can accurately calculate the position of the measuring end P in the laser tracker coordinate system and display it on the computer screen.

The measuring machine has the probe protection mechanism of Fig. 8. The probe is not directly fixed to the probe base, but is fixed on a movable seat, and the movable seat is accurately positioned relative to the probe base by the spring and the positioning mechanism. When the probe collides with the workpiece or other object from any direction, the positioning mechanism is disengaged, the contact pair in the positioning mechanism is disconnected, the measuring machine stops moving, and the probe and the measuring machine are protected.

When the laser tracker has to be moved, the target 6 in Fig. 7 does not move, the laser tracker moves and tracks, and it records the distance moved by the optical center of the laser tracker, the angle at which the laser beam is rotated, and the laser tracker is calculated by calculation. The new position of the optical center is converted by the coordinate system to maintain the uniformity of the measurement coordinate system.

The measurement system has the function of determining the position of the measuring machine relative to the laser tracker to determine its spatial position. Typically, a laser tracker is an incremental code measurement system that needs to know the distance between the optical center of the laser tracker and the target optical center at the initial position. The measurement system has the function of calibrating the distance between the optical center of the laser tracker and the optical center of the target at the measurement site. The working principle is to use a common laser interferometer for measuring the displacement of the line, aiming at the corner cube 4 mounted at the end of the horizontal arm 5 in Fig. 7, and adjusting the beam to the X axis, that is, the horizontal arm 5 The direction of the line. The laser tracker is aimed at the target 6. Move the horizontal arm 5 in the X direction while recording the readings of the normal laser interferometer and the laser tracker. In order to ensure the calibration accuracy, it is required to increase the distance of the horizontal arm 5 in the X direction and increase the number of sampling points. The data processing can simultaneously determine the distance between the optical center of the laser tracker and the target optical center at the calibration initial position, and the spatial relative position between the corner cube 4 and the optical center of the target 6.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coordinate measuring system capable of measuring internal and external characteristic elements of a large engineering object having a size of several tens of meters on the object to be measured, which has the characteristics of high precision, safe and reliable work, and low cost.

The invention will now be described in further detail with reference to the drawings and embodiments.

The invention proposes a large coordinate measuring system with laser tracking. Its working principle is shown in Figure 7.

It consists of a measuring machine, a laser tracker and a calculation control system. The measuring machine, the laser tracker and the control computing system are all movable from the requirements of being able to measure on-site at the object under test.

Develop or select the measuring machine according to the measured object and measurement requirements, including the X and z stroke of the measuring machine, the size of the 1 h in Figure 7, the length of the probe 9, etc., the probe and the revolving body of the probe, etc. Configure to meet measurement requirements.

The angle measuring device 7 in Fig. 7 can employ two electronic levels, which respectively measure the rotation of the main shaft 8 about the X and y axes, and the target 6 can adopt a cat's eye or a corner cube. The probe 10 can be used with a 3D analog probe (eg SP25) or a trigger probe.

The model of the measuring machine is established in the virtual coordinate measuring machine according to the structure, size, configuration and movement of the coordinate measuring machine. The model of the measured object is established according to the drawing of the object to be tested.

The measuring machine, laser tracker and calculation control system are installed at the measurement site. Move the measuring machine to the first position next to the object to be measured according to the measurement needs. A common line displacement measuring laser interferometer is used to aim at the corner ridge mirror 4 in Fig. 7, and the laser beam of the interferometer is adjusted to be parallel to the X-direction movement of the horizontal arm 5 of the measuring machine. The absolute distance between the target 6 and the optical center of the laser tracker is calibrated by moving the horizontal arm 5 in the full range of the X direction while recording a series of readings of the line displacement measuring laser interferometer and the laser tracker.

The measuring machine is used to measure several points on the object to be measured, and the laser tracker, the measuring machine and the coordinate system of the object to be measured are unified.

The virtual coordinate measuring machine is used to realize the optimization of the measurement scheme and the path planning, including the determination of the number of positions and specific positions that the measuring machine needs to move; the path planning and optimization of the horizontal arm, the main shaft and the measuring head revolving body of the measuring machine at various positions, Anti-collision and anti-laser tracker light loss inspection. The laser tracker needs to determine the number of positions to move and the specific position.

According to the path plan determined by the virtual coordinate measuring machine, automatic measurement is realized at the first position of the laser tracker and the measuring machine. The computer collects and stores the laser tracker readings of each sampling point (including the angle between the two axes of the laser tracker and the optical center of the laser tracker measured by the interferometer to the optical center of the target), and the angle measuring device Measured the angle of the spindle of the measuring machine around the x and y axes, the temperature of the spindle measured by the temperature measuring element, the angle of rotation of the probe's rotating body around its two axes, the deformation of the probe measured by the strain gauge, and the reading of the 3D probe.

After completing all the inspection work at one position of the measuring machine, the path planning is determined according to the virtual coordinate measuring machine, and the laser tracker is kept stationary, and the measuring machine is moved to the next position. In the process of moving the measuring machine, special attention should be paid to prevent the laser tracker from losing light, and on this basis, the coordinate system before and after the movement of the measuring machine is maintained.

According to the path plan determined by the virtual coordinate measuring machine, all measurement movements, data acquisition and storage at this position are completed at the new position of the measuring machine.

According to the path plan determined by the virtual coordinate measuring machine, if necessary, keep the target of the measuring machine stationary and move the laser tracker to the next position. In the process of moving the laser tracker, special attention should be paid to prevent the laser tracker from losing light, and on this basis, the coordinate system before and after the movement of the laser tracker is maintained.

According to the path plan determined by the virtual coordinate measuring machine, all measurement movements, data acquisition and storage at this position are completed at the new position of the laser tracker.

Repeat the above steps as needed until all measurement work is completed.

After the measurement is completed, move the measuring machine and laser tracker to a safe position.

The processing and analysis of the measurement data are performed, and the measurement results are given.

Claims

Rights request

A large three-coordinate measuring device with laser tracking, characterized in that it consists of a measuring machine, a laser tracker and a calculation control system, and a laser interferometer for measuring line displacement; the measuring machine is provided with: a column and a bottom thereof Wheels are provided to move the measuring machine to the object to be measured and close to the measured feature point; the horizontal arm mounted on the column can perform X-direction movement, and the spindle mounted at one end of the horizontal arm can make z-direction Movement, the other end of the horizontal arm is equipped with a corner prism; the upper end of the main shaft is equipped with a probe revolving body, and the revolving body of the measuring head can rotate horizontally and vertically; the probe is equipped with a probe on the rotating body, and the probe is equipped with a probe The probe has a strain gauge for measuring the deformation of the probe; the other end of the spindle is equipped with a target and a goniometer, and a temperature measuring component is attached to the spindle for temperature compensation;

The laser interferometer is aimed at the corner cube prism at the end of the horizontal arm. The beam of the laser interferometer is adjusted to be parallel to the movement of the horizontal arm. The laser tracker aims at the target and moves the horizontal arm in the direction, while recording the laser interferometer and the laser tracker. Reading, data processing can simultaneously determine the distance between the optical center of the laser tracker and the optical center of the target at the calibration initial position, and the spatial relative position between the corner prism and the optical center of the target;

The laser tracker is used to track and measure the position of the optical center point of the target. The angle measuring device is used to measure the deflection angle of the main axis relative to the object to be measured, and the strain gauge measures the bending deformation of the probe and compensates for the error. The device according to claim 1, wherein the device is provided with a probe protection mechanism, and the probe protection mechanism is a movable seat, and the movable seat is accurately positioned relative to the probe base by the spring and the positioning mechanism, the side head It is fixed on the movable seat, and the side head seat is fixed on the revolving body of the probe. When the probe collides with the workpiece or other objects from any direction, the positioning mechanism is disengaged, the contact pair in the positioning mechanism is disconnected, and the measuring machine stops moving. , The probe and measuring machine are protected. The device according to claim 1, wherein the angle measuring device is two electronic levels for measuring the rotation of the main shaft about the X and the axis.

A large three-coordinate measuring method with laser tracking, which is realized by means of a large-scale three-coordinate measuring device with laser tracking, and includes the following steps:

1) Install the measuring machine, laser tracker and calculation control system at the measurement site, move the measuring machine to the first position beside the object to be measured according to the measurement needs, and use the line displacement measuring laser interferometer to aim at the angle prism, and The laser beam of the interferometer is adjusted to be parallel to the X-direction motion of the horizontal arm of the measuring machine. By moving the horizontal arm in the full range of the X direction, while recording the line displacement measurement series of readings of the laser interferometer and the laser tracker, calibration The absolute distance between the target 6 and the optical center of the laser tracker;

2) Using the measuring machine to measure several points on the object to be measured, and realize the unification of the coordinate system of the laser tracker, the measuring machine and the object to be measured; 3) Optimization of the measurement scheme and path planning: including the determination of the number of positions and specific positions that the measuring machine needs to move; the path planning and optimization of the horizontal arm, the main shaft, the revolving body of the measuring machine at various positions, anti-collision and anti-laser Tracker lost light inspection; laser tracker needs to move the number of positions and the specific location is determined;

4) In the first position of the laser tracker and measuring machine, automatic measurement is realized. The computer collects and stores the laser tracker reading of each sampling point: including the angle of the two axes around the laser tracker and the measurement by the interferometer. The distance from the optical center of the laser tracker to the optical center of the target, the angle of the spindle of the measuring machine measured by the angle measuring device, and the angle of the spindle, the temperature of the spindle measured by the temperature measuring component, and the angle of rotation of the probe rotating body around the two axes , deformation of the probe measured by the strain gauge, three-dimensional probe reading;

5) After completing all the inspection work at one position of the measuring machine, the above path planning keeps the laser tracker in motion and moves the measuring machine to the next position. In the process of moving the measuring machine, special attention should be paid to prevent the laser tracker from losing light. And on the basis of this, keep the coordinate system one before and after the movement of the measuring machine;

6) According to the path plan determined by the virtual coordinate measuring machine, all measurement movement, data acquisition and storage at this position are completed at the new position of the measuring machine;

7) According to the path planning, if necessary, keep the target of the measuring machine not moving, move the laser tracker to the next position, and pay special attention to prevent the laser tracker from losing light during the process of moving the laser tracker. Maintaining a coordinate system before and after the movement of the laser tracker;

8) According to the path plan determined by the virtual coordinate measuring machine, all measurement movements, data acquisition and storage at this position are completed at the new position of the laser tracker;

9) Repeat the above steps as needed until all measurement work is completed.