Intelligent laser tracking system based on machine vision rapid light-off recovery

Abstract

The invention provides an intelligent laser tracking system based on machine vision rapid light interruption recovery, and relates to the technical field of laser tracking measurement. The method comprises a transverse turntable, a longitudinal turntable and a tracking head, the longitudinal rotary table is installed in the transverse rotary table, the tracking head is installed in the longitudinal rotary table, the first driving motor and the second driving motor support and drive the tracking head to rotate, and the tracking head comprises a laser assembly, a spectroscope assembly, a PSD sensing assembly, an absolute distance measuring instrument, a camera assembly and the like. A light beam emitted by the laser coincides with the main optical axis, the PSD sensor and the absolute range finder are located on the two sides of the cubic spectroscope respectively, a light beam emitted by the absolute range finder coincides with a light beam emitted by the laser through the light path regulator, and the tracking head integrates multiple sensors in a small space. Basic functions of a traditional laser tracker are realized, and a visual module is introduced to carry out light failure recovery processing.

Description

Technical Field

[0001] The invention relates to the technical field of laser tracking measurement, in particular to a method for determining the friction coefficient of a rough interface of a spur gear under a mixed lubrication state. Background Art

[0002] Laser tracker is one of the cutting-edge application fields of laser technology. Its core principle is to drive the laser beam to continuously aim at the measurement target through a two-axis rotating device, and give the position information of the measurement point in three-dimensional space in the form of spherical coordinates. The laser tracker is extremely precise. It integrates optics, mechanics, electricity, control, and calculation in the instrument structure. It has a series of advantages such as large size, high precision, high efficiency, real-time performance, and simple operation. It is widely used in various industrial places such as robot kinematics, industrial quality inspection, and large-scale mechanical assembly. It is an indispensable and important part of modern manufacturing.

[0003] Laser tracking is a highly comprehensive research field. With the research and development of related fields such as computer science, laser science, image processing, and automatic control in recent years, various types of new laser tracking systems have been introduced. The invention patent (CN114942014A) discloses a new type of laser tracker that uses machine vision and ranging modules for tracking and light failure recovery, with a relatively simple tracking head structure; however, tracking based entirely on vision has extremely high requirements for camera resolution and image processing algorithm performance, and the tracking accuracy and speed cannot be compared with the traditional PSD tracking method; in the light failure recovery design, the invention uses the last measurement value of the rangefinder before light failure as the radial distance for light failure recovery, which is also not considered. Summary of the invention

[0004] In order to solve a technical problem existing in the prior art, an embodiment of the present invention provides a method for determining the friction coefficient of the rough interface of a spur gear under a mixed lubrication state, so as to solve the problem that the friction coefficient of the meshing interface of spur gears under various working conditions cannot be easily obtained in the prior art, and the influence of the actual rough morphology on the friction coefficient of the tooth surface cannot be intuitively understood. The technical solution is as follows:

[0005] An intelligent laser tracking system based on machine vision rapid light interruption recovery, comprising: a transverse turntable, a longitudinal turntable and a tracking head;

[0006] The transverse turntable includes a first U-shaped right-angle frame and a first drive motor, wherein the first drive motor is mounted on a connecting plate of the first U-shaped right-angle frame, and the first drive motor drives the first U-shaped bracket frame to rotate;

[0007] The longitudinal turntable is installed in the first U-shaped right angle frame, and the longitudinal turntable includes a second U-shaped right angle frame and a second drive motor, the fixed end of the second drive motor is installed on the inner wall of the side plate of the first U-shaped right angle frame, the output end of the second drive motor is connected to the side plate of the second U-shaped right angle frame, and the other side plate of the second U-shaped right angle frame is connected to the first U-shaped right angle frame on the same side through a rotating shaft;

[0008] The tracking head is installed in the longitudinal turntable, and the first driving motor and the second driving motor support and drive the tracking head to rotate.

[0009] Optionally, the tracking head comprises:

[0010] A support rod assembly, wherein the support rod assembly is vertically mounted on the upper surface of the connecting plate of the second U-shaped right-angle frame;

[0011] A beam splitter assembly, the beam splitter assembly comprising a cubic beam splitter, an X-axis mounting frame and a Y-axis mounting frame, the bottom surface of the cubic beam splitter is mounted on the support rod assembly, the X-axis mounting frame is mounted on one side wall of the cubic beam splitter, the Y-axis mounting frame is mounted on the other side wall of the cubic beam splitter, and the X-axis mounting frame and the Y-axis mounting frame are vertically arranged in space;

[0012] A camera assembly, wherein the camera assembly is mounted on the beam splitter assembly;

[0013] A laser assembly, wherein the laser assembly is mounted at the end of the Y-axis mounting frame, and the beam path emitted by the laser assembly coincides with the main optical axis of the beam splitting assembly;

[0014] A PSD sensor assembly, wherein the PSD sensor assembly is mounted at an end of the X-axis mounting frame;

[0015] An absolute distance meter is mounted on a side wall of the cubic beam splitter facing away from the X-axis mounting frame.

[0016] Optionally, the Y-axis mounting frame comprises:

[0017] A first cage fixing frame, a second cage fixing frame, a first mounting rod and a first light shielding cylinder;

[0018] The first cage fixing frame and the second cage fixing frame are arranged in parallel, the centers of the first cage fixing frame and the second cage fixing frame are aligned with the center of the cubic beam splitter, and the laser assembly is installed in a cubic space formed by the first cage fixing frame and the second cage fixing frame;

[0019] Four first mounting rods are arranged in parallel to form a square space, one end of the four first mounting rods is respectively mounted at four end corners of the side of the cubic beam splitter, and the other ends of the four first mounting rods pass through the first cage fixing frame and are then mounted on the second cage fixing frame;

[0020] The first light-shielding tube is installed in the cubic space formed by the first mounting rod, one end of the first light-shielding tube is installed on the side wall of the cubic beam splitter, the other end of the first light-shielding tube is installed on the first cage fixing frame, and the first light-shielding tube is coaxially arranged with the laser assembly.

[0021] Optionally, the laser assembly comprises:

[0022] A laser body, a first fixing cylinder and a second fixing cylinder;

[0023] One end of the first fixing tube is installed in the through hole in the middle of the first cage fixing frame, and the second fixing tube is installed in the through hole in the middle of the second cage fixing frame;

[0024] The laser body is cylindrically arranged, one end of the laser body is installed in the cylindrical cavity of the first fixing cylinder, and the other end of the laser body is installed in the cylindrical cavity of the second fixing cylinder, wherein the first fixing cylinder and the second fixing cylinder are relatively symmetrically arranged.

[0025] Optionally, the X-axis mounting frame comprises:

[0026] An adjustable diameter fixing plate, an adapter plate, a second light-shielding cylinder, and a second mounting rod;

[0027] The second mounting rods are arranged in parallel to form a cubic space, one end of the second mounting rod is mounted at the four end corners of the cubic beam splitter, and the other end of the second mounting rod passes through the adapter plate and is mounted on the adjustable diameter fixing plate;

[0028] The second light-shielding cylinder is arranged in a cubic space formed by the second mounting rod, one end of the second light-shielding cylinder is mounted on a side wall of the stereoscopic beam splitter, the other end of the second light-shielding cylinder is mounted in a central through hole of the adapter plate, and the second light-shielding cylinder is coaxially arranged with the PSD sensor assembly.

[0029] A circular through hole is provided at the center of the adjustable diameter fixing plate for installing the PSD sensor assembly.

[0030] Optionally, the adjustable diameter fixing plate comprises: a rectangular plate and a positioning slide rail;

[0031] A circular through hole is arranged at the center of the rectangular plate, and at least three mounting grooves are evenly arranged on the rectangular plate along the periphery of the circular through hole, and a positioning slide rail is mounted on each mounting groove;

[0032] A positioning hole is provided in the installation groove, and the positioning bolt on the positioning slide rail is adapted to the positioning hole;

[0033] The positioning bolt is adjusted to adjust the position of the positioning slide rail in the positioning groove, so that the positioning slide rail can fix PSD sensor components of different diameters in the circular through hole of the adjustable diameter fixing plate.

[0034] Optionally, the PSD sensor assembly comprises:

[0035] A PSD sensor, the PSD sensor is arranged in a columnar shape, and the PSD sensor is fixed in the circular through hole of the rectangular plate through a plurality of the positioning slide rails;

[0036] A PSD circuit board is mounted on the PSD sensor and is electrically connected to the PSD sensor.

[0037] Optionally, the camera assembly is an industrial camera;

[0038] The support rod assembly is a telescopic support rod, and the support rod assembly can adjust the lifting and lowering of the stereoscopic beam splitter.

[0039] Optionally, an anti-reflection film is provided on the surface of the stereoscopic beam splitter, and the anti-reflection film is adapted to the wavelength of the laser body.

[0040] Optionally, the beam splitter assembly further includes a cage optical path adjuster, a third mounting rod and a third light shielding cylinder;

[0041] The cage optical path adjuster is mounted on a side of the stereoscopic beam splitter away from the Y-axis mounting frame through four third mounting rods;

[0042] The four third mounting rods are arranged in parallel to form a cubic space, and the four third mounting rods are mounted at four end corners of the stereoscopic beam splitter;

[0043] The third light-shielding tube is installed in the cubic space formed by the four third mounting rods, one end of the third light-shielding tube is installed on the three-dimensional beam splitter, and the other end of the third light-shielding tube is installed in the cage-type optical path regulator.

[0044] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0045] (1) The tracking head has an ingenious structure design, integrating multiple sensors in a small space. In addition to realizing the basic functions of a traditional laser tracker, it also introduces a visual module for light-break recovery processing;

[0046] (2) A method was designed to calibrate the optical axis of the core sensor inside the tracking head and then establish a mathematical model of the tracking head for error compensation. Compared with the traditional attitude calibration method, this method has lower requirements for experimental configuration;

[0047] (3) A new control model based on visual detection is designed to complete the light-break recovery, and the radial distance of the light-break recovery is estimated according to the image size of the cooperative target sphere;

[0048] (4) A PSD correction method using a single hidden layer neural network combined with an extreme learning machine was designed, which has a good correction effect on nonlinear distortion errors;

[0049] (5) The system is easy to operate, the workflow is clear, and the fully automatic tracking and recovery effect can greatly improve the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0051] Figure 1 A schematic diagram of the overall structure of a system provided by an embodiment of the present invention;

[0052] Figure 2 A schematic diagram of the structure of a tracking head provided by an embodiment of the present invention;

[0053] Figure 3 A schematic diagram of a system optical path provided by an embodiment of the present invention;

[0054] Figure 4 A schematic diagram of a target ball visual light-break index control model provided by an embodiment of the present invention;

[0055] Figure 5 A system workflow diagram provided for an embodiment of the present invention;

[0056] Figure 6 An exploded view of a tracking head provided by an embodiment of the present invention;

[0057] Figure 7 A schematic diagram of the structure of a horizontal turntable and a vertical turntable provided in an embodiment of the present invention;

[0058] Figure 8 A schematic structural diagram of a laser assembly provided in an embodiment of the present invention.

[0059] Reference numerals:

[0060] a. Horizontal turntable; b. Vertical turntable; c. Tracking head;

[0061] 1. Support rod assembly;

[0062] 2. Beam splitter assembly; 21. X-axis mounting frame; 211. Adjustable diameter fixing plate; 2111. Rectangular plate; 2112. Positioning slide rail; 212. Adapter plate; 213. Second light shielding cylinder; 214. Second mounting rod; 22. Y-axis mounting frame; 221. First cage fixing frame; 222. Second cage fixing frame; 223. First mounting rod; 224. First light shielding cylinder; 23. Cube beam splitter; 24. Cage optical path adjuster; 25. Third mounting rod; 26. Third light shielding cylinder;

[0063] 3. Camera components;

[0064] 4. Laser assembly; 41. Laser body; 42. First fixing cylinder; 43. Second fixing cylinder;

[0065] 5. PSD sensor assembly; 51. PSD sensor; 52. PSD circuit board;

[0066] 6. Absolute distance meter. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "one" or "the" do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0069] It should be noted that the terms "up", "down", "left", "right", "front", "back", etc. used in the present invention are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0070] In this embodiment, the tracking head uses the center of the cubic beam splitter as the reference point, and extends forward and backward to form the main optical axis of the instrument. The light beam emitted by the laser coincides with the main optical axis. The PSD sensor and the absolute rangefinder are located on both sides of the cubic beam splitter. The light beam emitted by the absolute rangefinder coincides with the light beam emitted by the laser through the optical path regulator. The light beam reflected back to the instrument by the cooperative target ball will pass through the optical path regulator and the cubic beam splitter successively, and the cubic reflector will reflect part of the return light into the PSD sensor; the system calculates the spherical coordinate value of the current target ball target according to the output of the absolute rangefinder and the PSD sensor, and drives the two-dimensional turntable to continuously track the target; when the target is lost, the system searches for the target ball through the industrial camera, and drives the two-dimensional turntable to turn to the target ball target to complete the system's light failure recovery. Compared with existing research results, the present invention has better integration, the tracking head has a sophisticated structural design, small size and light weight, the system has high measurement accuracy and good repeatability, and can be matched with an industrial camera to achieve full-automatic rapid light failure recovery, which greatly improves the measurement efficiency of the laser tracker. The specific implementation plan is as follows:

[0071] like Figures 1 to 8 As shown, the present invention provides an intelligent laser tracking system based on machine vision rapid light interruption recovery, comprising: a transverse turntable a, a longitudinal turntable b and a tracking head c;

[0072] The horizontal turntable a includes a first U-shaped right-angle frame and a first drive motor, the first drive motor is installed on the connecting plate of the first U-shaped right-angle frame, and the first drive motor drives the first U-shaped bracket frame to rotate; the longitudinal turntable b is installed in the first U-shaped right-angle frame, and the longitudinal turntable b includes a second U-shaped right-angle frame and a second drive motor, the fixed end of the second drive motor is installed on the inner wall of the side plate of the first U-shaped right-angle frame, the output end of the second drive motor is connected to the side plate of the second U-shaped right-angle frame, and the other side plate of the second U-shaped right-angle frame is connected to the first U-shaped right-angle frame on the same side through a rotating shaft; the tracking head c is installed in the longitudinal turntable b, and the first drive motor and the second drive motor support and drive the tracking head c to rotate.

[0073] In a specific implementation manner, the first U-shaped right-angle frame is larger than the second U-shaped right-angle frame, the first U-shaped right-angle frame includes two parallel side panels and a connecting plate connecting the two side panels, the second U-shaped right-angle frame also includes two parallel side panels and a connecting plate connecting the two side panels, and a first drive motor is arranged in the middle position of the lower side surface of the connecting plate of the first U-shaped right-angle frame. The first drive motor can drive the first U-shaped right-angle frame to rotate, which can be as follows Figure 1 The second U-shaped right angle frame can rotate left and right in the direction; one side plate of the second U-shaped right angle frame is installed on the side plate on the same side of the first U-shaped right angle frame through the second drive motor, the fixed end of the second rotating motor is fixed on the inner wall of the side plate of the first U-shaped right angle frame, the side plate of the second U-shaped right angle frame away from the second drive motor is connected to the other side plate of the first U-shaped right angle frame through the rotating shaft, the output shaft of the second drive motor and the connecting plate of the first U-shaped right angle frame are arranged in parallel, so the second drive motor can drive the second U-shaped right angle frame to rotate inside and outside, so that the horizontal turntable a and the vertical turntable b form a U-shaped frame structure with inner pitch and outer azimuth, and the pitch axis and the azimuth axis are both equipped with high-precision gratings for full closed-loop control; the tracking head c is a composite structure.

[0074] In a specific implementation manner, the tracking head c includes:

[0075] A support rod assembly 1, wherein the support rod assembly 1 is vertically mounted on the upper surface of the connecting plate of the second U-shaped right-angle frame;

[0076] A beam splitter assembly 2, the beam splitter assembly 2 comprising a cubic beam splitter 23, an X-axis mounting frame 21 and a Y-axis mounting frame 22, the bottom surface of the cubic beam splitter 23 is mounted on the support rod assembly 1, the X-axis mounting frame 21 is mounted on one side wall of the cubic beam splitter 23, the Y-axis mounting frame 22 is mounted on the other side wall of the cubic beam splitter 23, and the X-axis mounting frame 21 and the Y-axis mounting frame 22 are vertically arranged in space;

[0077] A camera assembly 3, wherein the camera assembly 3 is mounted on the beam splitter assembly 2;

[0078] A laser assembly 4, wherein the laser assembly 4 is mounted at the end of the Y-axis mounting frame 22, and the beam path emitted by the laser assembly 4 coincides with the main optical axis of the beam splitting assembly;

[0079] A PSD sensor assembly 5, wherein the PSD sensor assembly 5 is mounted at the end of the X-axis mounting frame 21;

[0080] The absolute distance meter 6 is mounted on the side wall of the cubic beam splitter 23 away from the X-axis mounting frame 21 .

[0081] In a specific embodiment, the Y-axis mounting frame 22 includes:

[0082] A first cage fixing frame 221, a second cage fixing frame 222, a first mounting rod 223 and a first light shielding cylinder 224;

[0083] The first cage fixing frame 221 and the second cage fixing frame 222 are arranged in parallel, the centers of the first cage fixing frame 221 and the second cage fixing frame 222 are aligned with the center of the cubic beam splitter 23, and the laser assembly 4 is installed in the cubic space formed by the first cage fixing frame 221 and the second cage fixing frame 222;

[0084] Four first mounting rods 223 are arranged in parallel to form a square space, one end of the four first mounting rods 223 is respectively mounted at four end corners of the side of the cubic beam splitter 23, and the other ends of the four first mounting rods 223 pass through the first cage fixing frame 221 and are then mounted on the second cage fixing frame 222;

[0085] The first light-shielding tube 224 is installed in the cubic space formed by the first mounting rod 223, one end of the first light-shielding tube 224 is installed on the side wall of the cubic beam splitter 23, and the other end of the first light-shielding tube 224 is installed on the first cage fixing frame 221, and the first light-shielding tube 224 is coaxially arranged with the laser assembly 4.

[0086] In a specific implementation manner, the laser assembly 4 includes:

[0087] Laser body 41, first fixing cylinder 42 and second fixing cylinder 43;

[0088] One end of the first fixing tube 42 is installed in the through hole in the middle of the first cage fixing frame 221, and the second fixing tube 43 is installed in the through hole in the middle of the second cage fixing frame 222;

[0089] The laser body 41 is cylindrically arranged, one end of the laser body 41 is installed in the cylindrical cavity of the first fixed cylinder 42, and the other end of the laser body 41 is installed in the cylindrical cavity of the second fixed cylinder 43, wherein the first fixed cylinder 42 and the second fixed cylinder 43 are relatively symmetrically arranged.

[0090] In a specific implementation manner, the X-axis mounting frame 21 includes:

[0091] An adjustable diameter fixing plate 211, an adapter plate 212, a second light shielding tube 213 and a second mounting rod 214;

[0092] The second mounting rods 214 are arranged in parallel and form a cubic space, one end of the second mounting rod 214 is mounted at the four end corners of the cubic beam splitter 23, and the other end of the second mounting rod 214 passes through the adapter plate 212 and is mounted on the adjustable diameter fixing plate 211;

[0093] The second light-shielding tube 213 is arranged in the cubic space formed by the second mounting rod 214, one end of the second light-shielding tube 213 is mounted on the side wall of the stereoscopic beam splitter, and the other end of the second light-shielding tube 213 is mounted in the central through hole of the adapter plate 212, and the second light-shielding tube 213 is coaxially arranged with the PSD sensor assembly 5.

[0094] A circular through hole is provided at the center of the adjustable diameter fixing plate 211 for mounting the PSD sensor assembly 5 .

[0095] In a specific implementation manner, the adjustable diameter fixing plate 211 comprises: a rectangular plate 2111 and a positioning slide rail 2112;

[0096] A circular through hole is provided at the center of the rectangular plate 2111, and at least three mounting grooves are evenly provided on the rectangular plate 2111 along the periphery of the circular through hole, and a positioning slide rail 2112 is installed on each mounting groove;

[0097] A positioning hole is provided in the installation groove, and the positioning bolt on the positioning slide rail 2112 is adapted to the positioning hole;

[0098] The positioning bolt is adjusted to adjust the position of the positioning rail 2112 in the positioning groove, so that the positioning rail 2112 can fix PSD sensor components 5 of different diameters in the circular through hole of the adjustable diameter fixing plate 211.

[0099] In a specific implementation manner, the PSD sensor assembly 5 comprises:

[0100] A PSD sensor 51, wherein the PSD sensor 51 is arranged in a columnar shape and is fixed in the circular through hole of the rectangular plate 2111 through a plurality of the positioning rails 2112;

[0101] A PSD circuit board 52 is mounted on the PSD sensor 51 and is electrically connected to the PSD sensor 51 .

[0102] In a specific implementation manner, the camera assembly 3 is an industrial camera;

[0103] The support rod assembly 1 is a telescopic support rod, and the support rod assembly 1 can adjust the lifting and lowering of the stereoscopic beam splitter.

[0104] In a specific implementation manner, an anti-reflection film is provided on the surface of the stereoscopic beam splitter, and the anti-reflection film is adapted to the wavelength of the laser body 41 .

[0105] In a specific implementation manner, the beam splitter assembly 2 further includes a cage optical path adjuster 24, a third mounting rod 25 and a third light shielding cylinder 26;

[0106] The cage optical path adjuster 24 is installed on the side of the stereoscopic beam splitter away from the Y-axis mounting frame 22 through the four third mounting rods 25;

[0107] The four third mounting rods 25 are arranged in parallel to form a cubic space, and the four third mounting rods 25 are installed at the four end corners of the stereoscopic beam splitter;

[0108] The third light-shielding tube 26 is installed in the cubic space formed by the four third mounting rods 25 , one end of the third light-shielding tube 26 is installed on the stereoscopic beam splitter, and the other end of the third light-shielding tube 26 is installed in the cage optical path regulator 24 .

[0109] The main structural features of the present invention are:

[0110] like Figure 1As shown, the tracking head uses the center of the cubic beam splitter as the reference point of the system optical path, and the line formed by the forward and backward extension of the reference point is used as the main optical axis of the tracking head; the two first fixed cylinders and the second fixed cylinder are respectively installed at the front and rear ends of the laser body, and then the laser body is fixed on the cage system by two cage fixing frames. At this time, the light beam emitted by the laser body coincides with the main optical axis of the tracking head, and the first cage fixing frame is tightly attached to the first light-shielding cylinder at the rear end of the cubic beam splitter; the PSD sensor and the PSD circuit board are located on the right side of the cubic beam splitter, the adjustable diameter fixing frame clamps the light-shielding ring of the PSD sensor, and then fixed to the cage system by the adapter plate. At this time, the center of the PSD sensor is facing the reference point, and a light-shielding device is also provided on the end of the cubic beam splitter close to the PSD sensor. tube; the absolute rangefinder is located on the left side of the cubic beam splitter, and the two are glued together with thermal conductive glue. The ranging laser emitted by the absolute rangefinder is adjusted by the cage optical path adjuster to coincide with the main optical axis of the tracking head, and is coupled with the laser beam emitted by the laser body; the industrial camera is located above the cubic beam splitter, and the two are glued together with thermal conductive glue. The lens of the industrial camera is an electric focusing lens, which can automatically focus according to the measurement value of the absolute rangefinder; the telescopic support rod is connected to the center position of the bottom shell of the cubic beam splitter through a cage connecting rod, and the reference point of the telescopic support rod is coincident with the intersection of the axis of the two-dimensional turntable. This point is also connected to the center screw hole of the bearing surface of the two-dimensional turntable, and then it is adjusted to make the tracking head the measurement reference point of the tracker.

[0111] In addition, the beam splitter prisms inside the cubic beam splitter and the cage optical path adjuster are coated with anti-reflection films that are compatible with the wavelength of the laser body; narrow-band filters are also installed on the three exits of the cubic beam splitter through which the light path passes to further eliminate the influence of ambient light.

[0112] The operation of this system in actual experiment is as follows:

[0113] An independent tracking head and a one-dimensional guide rail are fixed on an optical vibration isolation table. The main optical axis of the tracking head is aligned with the direction of motion of the guide rail. A two-dimensional optical scale plate is mounted on the guide rail load. After the above experimental arrangement is completed, the laser body, absolute rangefinder and industrial camera are turned on. The distance between the scale plate and the reference point of the tracking head and the coordinate positions of the laser spot, the rangefinder spot and the camera image center on the scale plate are recorded. The scale plate is moved to another new position through the guide rail for multiple times and these data are recorded again. A spatial rectangular coordinate system is established with the reference point of the tracking head as the origin of the coordinate system. The multiple sets of three-dimensional coordinate data of the three sensor optical axis intercept points obtained by the above method are subjected to three-dimensional straight line fitting based on the singular value decomposition method. The three spatial straight line expressions L obtained after fitting are L , L A , L C It is the mathematical model of the central optical axis of lasers, rangefinders and industrial cameras.

[0114] The target ball visual light-break index control model of the tracking head error model has the following basic principles:

[0115] When the instrument is interrupted during tracking, the industrial camera will immediately acquire the image in the current field of view and call the target detection algorithm to extract and calculate the diameter of the target ball's light shielding ring and the pixel coordinates of the reflection center in the image; the radial distance d between the target ball and the tracker's reference point is estimated by the ratio of the pixel size of the target ball's light shielding ring in the image to the actual size, and this distance is substituted as the x-axis value into the optical axis model L of the laser and camera. L and L C In the case where the x-axis coordinate is d, L L and L C The y-axis and z-axis values ​​of the laser are calculated, and their differences are calculated to obtain the distance difference Dy between the laser optical axis and the camera optical axis in the Y and Z directions at the current radial distance. C-L and Dz C-L ; Calculate the pixel coordinate difference py between the target sphere reflection center and the camera image center T-C and pz T-C , and according to the ratio between the camera image pixels and the real distance at different distances completed in advance, the two-pixel distance value is converted into the real distance value Dy T-C and Dz T-C ; Dy T-C and Dy C-L ,Dz T-C and Dz C-L Accumulate and sum to obtain the difference distance Dy of the target ball relative to the laser optical axis in the Y and Z directions at the current radial distance d. T-L and Dz T-L According to the formula and The arc values ​​that the two-dimensional turntable needs to rotate in the horizontal and pitch directions to realign the laser with the target ball are calculated, and the system controls the turntable movement to complete the light interruption recovery.

[0116] Based on this system, a single hidden layer neural network is used to correct the error of PSD nonlinear edge distortion. The specific methods include:

[0117] A high-precision two-dimensional electric translation stage is used to drive the laser to move in the X and Y directions, and a PSD sensor is placed on the other end to obtain the position information of the laser spot (in the initial state, the origin position of the laser shooting at the PSD target surface), and at least 1000 sets of experimental data are measured; the movement value of the translation stage in the X and Y directions is used as the binary input of the neural network, and the corresponding return value of the PSD sensor is used as the binary output of the neural network; according to the extreme learning machine (ELM) algorithm theory, the weights and biases from the input layer to the hidden layer are randomly given, and then the above multiple sets of experimental data are imported into its input and output layers to obtain the weights from the hidden layer to the output layer; a neural network that can perform PSD nonlinear correction is established.

[0118] The system workflow of the present invention is as follows Figure 5 The detailed description is as follows:

[0119] After receiving the power-on command, the system will first check the serial port names of all sensors. After confirming that they are correct, it will connect all sensors to complete the system power-on and the system will enter the running state.

[0120] The system initialization work includes the initial parameter setting of each component, the optical axis offset check, etc. After the parameter settings are completed, the tracking measurement function can be turned on, and the target ball is placed at the point to be measured. At this moment, the system is in the light-off state;

[0121] The turntable rotates toward the target according to the real-time instructions given by the visual index control model. When the light emitted by the laser body enters the target sphere, the PSD sensor component outputs the offset coordinates, and the system enters the light alignment state.

[0122] According to the real-time spherical coordinates of the target ball calculated by the output coordinates of the PSD sensor component and the distance value of the absolute rangefinder, the horizontal turntable and the vertical turntable continue to rotate until the output coordinates of the PSD sensor component are zero, at which time the system enters the alignment state;

[0123] In the aligned state, the target ball coordinates can be measured and recorded. After the measurement is completed, the target ball is moved to another measurement point and measured again until all the points to be measured are measured.

[0124] If the system enters the light-off state due to the target ball moving too fast or the light path being blocked during the movement, the system will perform the target search task again until it enters the alignment state again;

[0125] If all the points to be measured have been measured, the system will perform point cloud data fitting according to the selected fitting graphic object, and after the fitting is completed, the basic geometric parameters will be output as the final result;

[0126] Finally, re-measure points and export data to end the tracking process and return to the basic operating state.

[0127] The tracking head structure of the present system is exquisitely designed, and multiple sensors are integrated in a relatively small space. In addition to realizing the basic functions of the traditional laser tracker, a visual module is introduced to perform light failure recovery processing; the present invention designs a method for calibrating the optical axis of the core sensor inside the tracking head and then establishing a mathematical model of the tracking head for error compensation. Compared with the traditional attitude calibration method, the present method has lower requirements for experimental configuration; the present invention designs a brand-new control model based on visual detection to complete light failure recovery, and estimates the radial distance of light failure recovery according to the image size of the cooperative target sphere; the digital image processing algorithm of the present invention for the cooperative target sphere can accurately calculate its reflection center coordinates and image size; the single hidden layer neural network of the present invention combined with the PSD correction method of the extreme learning machine has a good correction effect on nonlinear distortion errors; the operation of the present system is simple and easy to use, the work flow is clear and concise, and the fully automatic tracking recovery effect can greatly improve the detection efficiency

[0128] The following points need to be explained:

[0129] (1) The drawings of the embodiments of the present invention only involve structures related to the embodiments of the present invention. Other structures may refer to conventional designs.

[0130] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present invention, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0131] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0132] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An intelligent laser tracking system based on machine vision for rapid light-off recovery, characterized in that: include: Transverse turntable, longitudinal turntable and tracking head; The transverse turntable includes a first U-shaped right-angle frame and a first drive motor, wherein the first drive motor is mounted on a connecting plate of the first U-shaped right-angle frame, and the first drive motor drives the first U-shaped bracket frame to rotate; The longitudinal turntable is installed in the first U-shaped right angle frame, and the longitudinal turntable includes a second U-shaped right angle frame and a second drive motor, the fixed end of the second drive motor is installed on the inner wall of the side plate of the first U-shaped right angle frame, the output end of the second drive motor is connected to the side plate of the second U-shaped right angle frame, and the other side plate of the second U-shaped right angle frame is connected to the first U-shaped right angle frame on the same side through a rotating shaft; The tracking head is installed in the longitudinal turntable, and the first driving motor and the second driving motor support and drive the tracking head to rotate.

2. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 1 is characterized in that: The tracking head comprises: A support rod assembly, wherein the support rod assembly is vertically mounted on the upper surface of the connecting plate of the second U-shaped right-angle frame; A beam splitter assembly, the beam splitter assembly comprising a cubic beam splitter, an X-axis mounting frame and a Y-axis mounting frame, the bottom surface of the cubic beam splitter is mounted on the support rod assembly, the X-axis mounting frame is mounted on one side wall of the cubic beam splitter, the Y-axis mounting frame is mounted on the other side wall of the cubic beam splitter, and the X-axis mounting frame and the Y-axis mounting frame are vertically arranged in space; A camera assembly, wherein the camera assembly is mounted on the beam splitter assembly; A laser assembly, wherein the laser assembly is mounted at the end of the Y-axis mounting frame, and the beam path emitted by the laser assembly coincides with the main optical axis of the beam splitting assembly; A PSD sensor assembly, wherein the PSD sensor assembly is mounted at an end of the X-axis mounting frame; An absolute distance meter is mounted on a side wall of the cubic beam splitter facing away from the X-axis mounting frame.

3. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 2 is characterized in that: The Y-axis mounting frame comprises: A first cage fixing frame, a second cage fixing frame, a first mounting rod and a first light shielding cylinder; The first cage fixing frame and the second cage fixing frame are arranged in parallel, the centers of the first cage fixing frame and the second cage fixing frame are aligned with the center of the cubic beam splitter, and the laser assembly is installed in a cubic space formed by the first cage fixing frame and the second cage fixing frame; Four first mounting rods are arranged in parallel to form a square space, one end of the four first mounting rods is respectively mounted at four end corners of the side of the cubic beam splitter, and the other ends of the four first mounting rods pass through the first cage fixing frame and are then mounted on the second cage fixing frame; The first light-shielding tube is installed in the cubic space formed by the first mounting rod, one end of the first light-shielding tube is installed on the side wall of the cubic beam splitter, the other end of the first light-shielding tube is installed on the first cage fixing frame, and the first light-shielding tube is coaxially arranged with the laser assembly.

4. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 3 is characterized in that: The laser assembly comprises: A laser body, a first fixing cylinder and a second fixing cylinder; One end of the first fixing tube is installed in the through hole in the middle of the first cage fixing frame, and the second fixing tube is installed in the through hole in the middle of the second cage fixing frame; The laser body is cylindrically arranged, one end of the laser body is installed in the cylindrical cavity of the first fixing cylinder, and the other end of the laser body is installed in the cylindrical cavity of the second fixing cylinder, wherein the first fixing cylinder and the second fixing cylinder are relatively symmetrically arranged.

5. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 4 is characterized in that: The X-axis mounting frame comprises: An adjustable diameter fixing plate, an adapter plate, a second light-shielding cylinder, and a second mounting rod; The second mounting rods are arranged in parallel to form a cubic space, one end of the second mounting rod is mounted at the four end corners of the cubic beam splitter, and the other end of the second mounting rod passes through the adapter plate and is mounted on the adjustable diameter fixing plate; The second light-shielding cylinder is arranged in a cubic space formed by the second mounting rod, one end of the second light-shielding cylinder is mounted on a side wall of the stereoscopic beam splitter, the other end of the second light-shielding cylinder is mounted in a central through hole of the adapter plate, and the second light-shielding cylinder is coaxially arranged with the PSD sensor assembly. A circular through hole is provided at the center of the adjustable diameter fixing plate for installing the PSD sensor assembly.

6. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 5 is characterized in that: The adjustable diameter fixing plate comprises: a rectangular plate and a positioning slide rail; A circular through hole is arranged at the center of the rectangular plate, and at least three mounting grooves are evenly arranged on the rectangular plate along the periphery of the circular through hole, and a positioning slide rail is mounted on each mounting groove; A positioning hole is provided in the installation groove, and the positioning bolt on the positioning slide rail is adapted to the positioning hole; The positioning bolt is adjusted to adjust the position of the positioning slide rail in the positioning groove, so that the positioning slide rail can fix PSD sensor components of different diameters in the circular through hole of the adjustable diameter fixing plate.

7. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 6 is characterized in that: The PSD sensing assembly comprises: A PSD sensor, the PSD sensor is arranged in a columnar shape, and the PSD sensor is fixed in the circular through hole of the rectangular plate through a plurality of the positioning slide rails; A PSD circuit board is mounted on the PSD sensor and is electrically connected to the PSD sensor.

8. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 7 is characterized in that: The camera assembly is an industrial camera; The support rod assembly is a telescopic support rod, and the support rod assembly can adjust the lifting and lowering of the stereoscopic beam splitter.

9. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 8 is characterized in that: The surface of the stereoscopic beam splitter is provided with an anti-reflection film, and the anti-reflection film is adapted to the wavelength of the laser body.

10. The intelligent laser tracking system based on machine vision rapid light interruption recovery according to claim 9, characterized in that: The beam splitter assembly also includes a cage optical path adjuster, a third mounting rod and a third light shielding cylinder; The three-dimensional beam splitter is mounted on a side away from the Y-axis mounting frame by four third mounting rods; The four third mounting rods are arranged in parallel to form a cubic space, and the four third mounting rods are mounted at four end corners of the stereoscopic beam splitter; The third light-shielding tube is installed in the cubic space formed by the four third mounting rods, one end of the third light-shielding tube is installed on the three-dimensional beam splitter, and the other end of the third light-shielding tube is installed in the cage-type optical path regulator.

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