CN104807437A - Multi-light-path self-calibration laser tracking measurement system - Google Patents

Abstract

The invention relates to the field of laser measurement, in particular to a multi-light-path self-calibration laser tracking measurement system. The system comprises a laser head, a target lens and more than three laser tracking heads. Compared with a conventional laser tracker which only has one path of measurement laser and requires introduction of angle measurement information to a measurement result, the multi-light-path self-calibration laser tracking measurement system adopts a multi-lateral positioning method to realize position calculation of a target lens, only length information is required for each laser tracking measurement light path, and the spatial position measurement accuracy of the target lens is improved greatly; meanwhile, under the condition of continuous irradiation of three paths of laser, when laser cut-off happens accidentally to any laser path, the overall measurement is not affected, and the measurement work stability is greatly improved.

Description

A multi-optical path self-calibration laser tracking measurement system

technical field

The invention relates to the field of laser measurement, in particular to a multi-optical path self-calibration laser tracking measurement system.

Background technique

The laser tracker is a high-precision large-scale measuring instrument in the industrial measuring system. It has the characteristics of high measurement accuracy, high efficiency, large measurement space, and ease of use. It is widely used in automobile manufacturing, shipbuilding, aircraft manufacturing, aerospace and other fields. Laser tracker is actually a combination of laser interferometric ranging and automatic tracking total station, usually composed of laser head, laser tracking head, target mirror, environmental compensator and other accessories; traditional laser tracker only uses one laser Carry out the tracking test, the position of the measurement point is measured by spherical coordinates, and the angle measurement information of the laser tracker is introduced into the measurement result. Due to the limited angle measurement accuracy of the laser tracker, the angle error will affect the three-dimensional coordinates of the measurement point during long-distance measurement. There is an error amplification effect, which reduces the accuracy of the measurement point.

Contents of the invention

The purpose of the present invention is to overcome the problem that only one laser track is used for tracking measurement in the prior art, and the accuracy of the measurement result is reduced due to angle errors in the measurement results, and to provide a multi-channel self-calibrating laser tracking measurement with multiple measurement lasers and more stable work system; it also includes more than N laser tracking heads, and N is a natural number above 3; the laser head emits N-way lasers, and the N-way lasers are sent to the corresponding laser tracking heads respectively, and each laser tracking head will receive all the way The laser is reflected to the target mirror, and the target mirror reflects the original path of each laser back to the laser head, and the laser interference distance measurement is realized in the laser head.

Further, the laser head includes a beam splitter, a laser reflection device, N photoelectric detection devices, N laser emitters and N position sensitive detectors; the laser emitter, photoelectric detection device and position sensitive detectors are connected with the laser One-to-one correspondence of tracking heads;

The beam splitter splits the laser light emitted by the laser transmitter to the photoelectric detection device and the laser reflection device respectively, and the N-way laser light is respectively reflected by the laser reflection device to the corresponding laser tracking head, and the laser tracking head reflects the received laser light to the The target mirror, and reflect the loop laser reflected from the original path of the target mirror back to the laser reflection device, and the loop laser reflected by the laser reflection device is split by the spectroscope to the position sensitive detector and the photoelectric detection device;

The position-sensitive detector is used to adjust the position and angle of the corresponding laser tracking head according to the received laser position; the photoelectric detection device is used to detect the state of laser interference, and finally realize the measurement of the interference optical path distance.

Further, the laser reflection device is N mutually independent laser plane reflectors, and the laser plane reflectors correspond to the laser tracking heads one by one.

Further, the laser tracking head includes a three-dimensional motion platform, an arc guide rail, an arc motion device (that is, an electromechanical device that cooperates with the arc guide rail to realize arc motion), a guide rail slider, a rotating motor, a moving magnetic ring, and a tracking reflection The tracking mirror includes a fixed spherical shell with an open upper end and a hemispherical mirror body; the bottom of the hemispherical mirror body is provided with an inlaid magnetic ring.

Further, the inlaid magnetic ring is located at the lower hemisphere of the hemispherical mirror body, preferably at a latitude of 60±10 degrees.

Further, the inlaid magnetic ring includes more than one permanent magnets forming a ring, and the magnetic field direction of each permanent magnet is consistent, and the preferred number of permanent magnets is 64, 128 or 256.

Further, the hemispherical mirror body includes two types of measuring mirror body and calibration mirror body with the same radius.

Further, the measuring mirror body has an end plane passing through the center of the sphere as a laser reflecting surface.

Further, the laser reflection surface of the calibration mirror body is three orthogonal planes with a common spherical center.

Preferably, the end plane of the calibration mirror body is located at a latitude of 45±10 degrees in the upper hemisphere.

Compared with the prior art, the present invention has beneficial effects : Compared with the traditional laser tracker, there is only one measurement laser, the position of the measurement point is measured by spherical coordinates, and the angle measurement information of the laser tracker is introduced into the measurement result, Due to the limited angle measurement accuracy of the laser tracker, the angle error has an error amplification effect on the three-dimensional coordinates of the measurement point during long-distance measurement, which reduces the accuracy of the measurement point. The multi-optical path self-calibration laser tracking measurement system provided by the present invention uses the multilateral positioning method to realize the calculation of the measurement point of the target mirror. Each laser tracking measurement optical path only needs length information, which greatly improves the spatial position measurement accuracy of the target mirror. At the same time, in the case of ensuring that the 3-way laser light is not interrupted, any other laser light path will be accidentally cut off, which will not affect the overall measurement, which greatly increases the stability of the measurement work.

Description of drawings:

Fig. 1 is a schematic diagram of a multi-optical path self-calibrating laser tracking measurement system in Embodiment 1 of the present invention.

Fig. 2 is a schematic diagram of the calibration principle of a single laser tracking head in Embodiment 1 of the present invention.

Fig. 3 is a schematic diagram of the structure of the measuring mirror body laser tracking head in Embodiment 1 of the present invention.

Fig. 4 is a schematic diagram of the structure of the calibration mirror body laser tracking head in Embodiment 1 of the present invention.

Fig. 5 is a structural diagram of a measuring mirror body in Embodiment 1 of the present invention.

FIG. 6 is a structure diagram of a calibration mirror body in Embodiment 1 of the present invention.

Marks in the figure: 1-laser head, 11-laser emitter, 12-beam splitter, 13-position sensitive detector, 14-photoelectric detection device, 15-laser reflection device, 2-target mirror, 3-laser tracking head, 31-Arc guide rail, 32-Guide rail slider, 33-Rotary motor, 34-Moving magnetic ring, 35-Tracking mirror, 351-Fixed spherical shell, 352-Hemispherical mirror body, 353-Inlaid magnetic ring, 354 -end plane, 355-three orthogonal planes, 36-arc motion device.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

Embodiment 1: As shown in Figures 1-6, the purpose of this embodiment is to overcome the limited accuracy of angle measurement of traditional laser trackers, and the problem that the angle error has an error amplification effect on the three-dimensional coordinates of the measurement point during long-distance measurement. The multi-optical path self-calibration laser tracking measurement system provided by the invention uses the multilateral positioning method to realize the calculation of the measurement point of the target mirror. Each laser tracking measurement optical path only needs length information, which greatly improves the spatial position measurement accuracy of the target mirror. Multi-optical path self-calibration laser tracking measurement system; it includes a laser head 1 and a target mirror 2 as shown in Figure 1, and also includes 4 laser tracking heads 3; the laser head 1 emits 4 lasers, and the 4 lasers are respectively sent to 4 laser tracking heads 3, each laser tracking head 3 reflects the laser light received by itself to the target mirror 2.

Further, the laser head 1 includes a beam splitter 12, a 4-way photoelectric detection device 14, a 4-way laser emitter 11, 4 position sensitive detectors 13 and 4 independent laser reflection devices 15 (such as a laser reflection plane mirror); 4 laser transmitters 11, 4 position-sensitive detectors 13, 4 independent laser reflection devices 15, 4 photoelectric detection devices 14 correspond to the 4 laser tracking heads 3 respectively, and can be adjusted by adjusting the The angle of the laser reflection device is used to adjust the reflection angle of the laser. ;

The beam splitter 12 splits the laser light emitted by the laser emitter 11 to the photoelectric detection device 14 and the laser reflection device 15 respectively, and the laser tracking head 3 reflects the laser light reflected by the laser reflection device 15 to the target mirror 2, and the The loop laser reflected back by the mirror 2 is reflected back to the laser reflection device 15 by the original path, and the loop laser reflected by the laser reflection device 15 is split by the beam splitter 12 to the position sensitive detector 13 and the photoelectric detection device 14;

The position-sensitive detector 13 is used to adjust the position and angle of the corresponding laser tracking head 3 according to the received laser position; the photoelectric detection device is used to detect the state of laser interference, and finally realize the measurement of the interference optical path distance.

Further, the laser tracking head 3 includes a three-dimensional motion platform (shown in Figure 3 and Figure 4), an arc guide rail 31, a guide rail slider 32, a rotating motor 33, a moving magnetic ring 34, a tracking mirror 35, and an arc motion device 36, the tracking reflector 35 includes a fixed spherical shell 351 with an open upper end and a hemispherical mirror body 352; the bottom of the hemispherical mirror body 352 is provided with an inlaid magnetic ring 353, and the fixed spherical shell 351 is used for The hemispherical mirror body 352 is fixed.

Described arc guide rail 31 is installed on the described three-dimensional motion platform, and described arc motion device 36 is installed on the arc guide rail 31, and cooperates with described arc guide rail 31 to realize arc movement, and described guide rail slide block 32 Installed on the arc moving device 36, the rotary motor 33 with the moving magnetic ring 34 is installed on the guide rail slider 32, and the tracking mirror 35 is installed above the moving magnetic ring 34, when the moving magnetic ring When the ring 34 rotates with the rotary motor 33, the tracking reflector 35 will follow the rotation under the action of the magnetic force; at the same time, when the guide rail slide block 32 moves under the drive of the arc motion device, the tracking reflector 35 will also Follow the movement under the action of magnetic force; after the installation is completed, because the inlaid magnetic ring 353 is used to cooperate with the moving magnetic ring 34 to realize non-contact rotation, the hemispherical mirror body 352 is in the process of movement, and its spherical center is only in contact with the hemispherical mirror body 352 and the accuracy of the fixed spherical shell 351 are related, but not related to the accuracy of the moving guide rail, which simplifies the existing laser tracking device and improves the system accuracy.

Further, the inlaid magnetic ring 353 is located at the lower hemisphere of the hemispherical mirror body, preferably at a latitude of 60 degrees.

Further, the fixed spherical shell 351 and the hemispherical mirror body 352 are made of non-magnetic materials, preferably ceramic materials.

Further, the inlaid magnetic ring 353 includes more than one ring-shaped permanent magnets, and the magnetic fields of each permanent magnet have the same direction. The preferred number of permanent magnets is 128. Similarly, the moving magnetic ring 34 is also more than one ring-shaped ring Composed of permanent magnets, the magnetic field direction of each permanent magnet is consistent. The moving magnetic ring 34 is preferably a permanent magnet. Since the mosaic magnetic ring 353 is used to cooperate with the moving magnetic ring 34 to realize non-contact rotation, during the movement of the hemispherical reflector, its spherical center is only related to the precision of the hemispherical reflector body 352 and the fixed spherical shell 351, but not to the accuracy of the moving guide rail. The precision is irrelevant, avoiding the control of the laser tracking reflector by interlacing the rotation axes, simplifying the existing laser tracking device, and improving the system precision.

Further, the hemispherical mirror body includes two types of measuring mirror body and calibration mirror body with the same radius.

Further, the measuring mirror body has an end plane 354 passing through the center of the sphere as a laser reflection surface, that is, the measuring mirror body is a standard hemispherical surface whose end plane is located at a latitude of 0 degrees.

Further, the laser reflection surface of the calibration mirror body is a three-orthogonal plane 355 with a common sphere center, that is, the common apex of the three orthogonal planes 355 is located at the center of the hemisphere; at the same time, there are three orthogonal planes with a common sphere center The end plane of the planar collimating mirror body is preferably arranged at a latitude of 45° in the upper hemisphere.

Further, the laser tracking head 3 has a bird's nest position 37 (as shown in FIG. 2 ), which is used to realize the initialization of the ranging function of the laser tracking head 3 . During initialization, after placing the target mirror 2 at the position of the bird's nest 37, measure the distance of the target mirror 2, and initialize the distance to a given value (the design parameters of the laser tracking head 3 are accurately given and the laser tracking head 3 measures the center of the reflector body distance to the center of the bird’s nest target mirror).

When the multi-optical path self-calibrating laser tracking measurement system provided in this embodiment starts to be used, initial calibration should be performed, and the laser head 1 is placed in the position of the corresponding laser light path, so that the tracking mirror 35 in the laser tracking head 3 (here When the tracking mirror should be a calibration mirror body) can receive the laser. Adjust the position of the laser tracking head 3 so that the laser is incident on any one of the three orthogonal reflection planes of the calibration mirror body, at this time the laser enters the position sensitive detector in the laser head 1 along the reflection optical path . The attitude of the three-dimensional motion platform of the laser tracking head 3 is adjusted according to the laser position of the position-sensitive detector, and finally the incident point of the laser is adjusted to the spherical center point of the calibration mirror body (that is, the common vertex of the three orthogonal planes). At the same time, the photoelectric detection device 14 detects reflected laser light (referring to the laser light reflected back into the laser head 1 by the laser tracking head 3 and split to the photoelectric detection device 14 by the beam splitter 12) and emitted laser light (referring to the laser light in the laser head 1). When the laser emitted by the transmitter 11 and split into the photoelectric detection device 14 by the spectroscope 12 is in an interference state, the initial position adjustment of the laser tracking head 3 is completed.

Before the subsequent measurement work starts, the laser tracking head 3 should change the calibration mirror body into a measurement mirror body. The center of the sphere is at the same location. Place the target mirror 2 at the bird's nest position of the current laser tracking head 3, adjust the angle of the laser tracking head 3, so that the reflected laser light of the target mirror 2 can be reflected back to the position in the laser head 1 by the laser tracking head 3 On the sensitive detector 13 , adjust the arc motion device 36 and the rotating motor 33 of the laser tracking head 3 according to the measurement results of the position sensitive detector 13 , and finally adjust the incident point of the laser to the spherical center point of the target mirror 2 . At this time, the laser optical path is in the state of interference, and the current measurement distance is set to a given value (the design parameters of the laser tracking head are precisely given the distance from the center of the sphere of the measuring mirror body to the center of the bird's nest target mirror in the laser tracking head 3). Place the target mirror 2 at a fixed position, and measure the current distance L1 of the target mirror 2. The distances L2, L3, and L4 from the 4-way laser tracking head 3 to the same fixed position are acquired according to the above method. When the last laser beam completes the distance measurement, the current target target mirror 2 is fixed, and another target mirror 2 is used to guide the other 3 laser tracking optical paths to this fixed target mirror, and the angle of the laser tracking head 3 is adjusted according to the above method. Make each laser tracking optical path in the interference state, and set the laser interference ranging at this time to the original measurement distance L1, L2, L3, L4, and the system initialization is completed. After the system initialization is completed, the spatial position measurement of the target mirror can be realized according to the multilateral positioning method.

In this embodiment, if any one of the four lasers is cut off (that is, as long as three lasers are normal at the same time), the overall measurement will not be affected.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that the multi-optical path self-calibration laser tracking measurement system; it includes the laser head 1 and the target mirror 2 as shown in Figure 1, and also includes 6 laser tracking heads 3. The laser head 1 emits 6 laser beams, and the 6 laser beams are respectively sent to 6 laser tracking heads 3 , and each laser tracking head 3 reflects one laser beam received by itself to the target mirror 2 .

In this embodiment, if any three of the six lasers are cut off (that is, as long as three lasers are normal at the same time), the overall measurement will not be affected.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that the multi-optical path self-calibration laser tracking measurement system; it includes the laser head 1 and the target mirror 2 as shown in Figure 1, and also includes 3 laser tracking heads 3. The laser head 1 emits 3 laser beams, and the 3 laser beams are respectively sent to the 3 laser tracking heads 3, and each laser tracking head 3 reflects the laser light received by itself to the target mirror 2.

Claims (10)

1. A multi-optical path self-calibration laser tracking measurement system, comprising a laser head and a target mirror, is characterized in that it also includes more than N laser tracking heads, and N is a natural number above 3; said laser head emits N-way lasers, and N-way The laser light is sent to N laser tracking heads respectively, and each laser tracking head reflects the laser light received by itself to the target mirror, and the target mirror reflects the original path of each laser light back to the laser head, and realizes laser interference distance measurement in the laser head . 2. The multi-optical path self-calibration laser tracking measurement system as claimed in claim 1, wherein the laser head comprises a beam splitter, a laser reflection device, an N-way photoelectric detection device, an N-way laser emitter and N position sensitive Detectors; laser emitters, photoelectric detection devices and position-sensitive detectors are in one-to-one correspondence with the laser tracking head; The beam splitter splits the laser light emitted by the laser transmitter to the photoelectric detection device and the laser reflection device respectively, and the N-way laser light is respectively reflected by the laser reflection device to the corresponding laser tracking head, and the laser tracking head reflects the received laser light to the The target mirror, and reflect the loop laser reflected from the original path of the target mirror back to the laser reflection device, and the loop laser reflected by the laser reflection device is split by the spectroscope to the position sensitive detector and the photoelectric detection device; The position-sensitive detector is used to judge and adjust the position and angle of its corresponding laser tracking head according to the received laser light; the photoelectric detection device is used to detect the state of laser interference, and finally realize the measurement of the interference optical path distance. 3. multi-optical path self-calibration laser tracking measuring system as claimed in claim 1, is characterized in that, described laser reflector is N mutually independent laser plane reflectors, and described laser plane reflector and described laser tracking head One to one correspondence. 4. The multi-optical path self-calibration laser tracking measurement system as claimed in claim 1, wherein the laser tracking head includes a three-dimensional motion platform, an arc guide rail, an arc motion device, a guide rail slider, a rotating motor, a moving magnetic A ring and a tracking mirror, the tracking mirror includes a fixed spherical shell with an open upper end and a hemispherical mirror body; the bottom of the hemispherical mirror body is provided with an inlaid magnetic ring. 5. The multi-optical path self-calibrating laser tracking measurement system according to claim 4, wherein the inlaid magnetic ring is located at the lower hemisphere of the hemispherical mirror body, preferably at a latitude of 60±10 degrees. 6 . The multi-optical path self-calibrating laser tracking measurement system according to claim 4 , wherein the mosaic magnetic ring includes more than one ring-shaped permanent magnets, and the magnetic fields of each permanent magnet have the same direction. 7 . The multi-optical path self-calibrating laser tracking measurement system according to claim 4 , wherein the hemispherical mirror body includes two types of measuring mirror body and calibration mirror body with the same radius. 8. The multi-optical path self-calibrating laser tracking measurement system according to claim 7, wherein the measuring mirror body has an end plane passing through the center of the sphere as a laser reflecting surface. 9. The multi-optical path self-calibration laser tracking measurement system according to claim 7, wherein the laser reflection surfaces of the calibration mirror body are three orthogonal planes with a common spherical center. 10. The multi-optical path self-calibrating laser tracking measurement system according to claim 7, wherein the end plane of the calibration mirror body is located at a latitude of 45±10 degrees in the upper hemisphere.