A rotating mirror type binocular vision laser tracking broken light recovery system and method

Abstract

The application discloses a rotating mirror type binocular vision laser tracking light break recovery system and method. The system comprises a rotating mirror type laser tracker and a binocular vision module, two cameras in the binocular vision module are symmetrically installed on both sides of a laser beam, and camera visual axes and a laser optical axis are reflected to a working area through a rotating mirror of the tracker. The method comprises the following steps: a virtual imaging plane model in which the camera visual axes and the laser optical axis are coincident is constructed in advance; after the light break occurs, an infrared illumination light source of a vision system is modulated, frame difference images of modulation wave crests and troughs are acquired and processed, a current position of a target mirror and a predicted light break recovery rotation angle are obtained, and error compensation is performed on the current position and the predicted light break recovery rotation angle; and corresponding motors are driven to rotate according to the compensated light break recovery rotation angle, so that the laser beam is re-aligned to the target mirror. The application reduces the coaxial installation difficulty of a vision system of a rotating mirror type laser tracker, and improves the target mirror recognition rate and the light break recovery servo angle accuracy in a large range of complex environments.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser tracking measurement technology and instruments, in particular to a rotating mirror binocular vision laser tracking broken light recovery system and method. BACKGROUND

[0002] The laser tracker is a typical instrument in the field of precise measurement of large-scale space coordinates, and plays an important role in industrial applications such as measurement of large mechanical parts and assembly monitoring of large equipment. In laser tracking measurement, the laser beam needs to be aimed at the target mirror to ensure measurement efficiency. However, in actual operation, the laser beam will deviate from the target mirror and appear broken light due to various external factors. After the laser tracker is broken, the broken light recovery is mainly achieved through manual guidance and machine vision guidance. Compared with manual guidance, machine vision guidance is more efficient. However, machine vision guidance requires the visual axis of the vision system to be synchronously rotated with the laser optical axis. Due to the special structure of the rotating mirror laser tracker, the pitch rotation angle of the laser beam is twice the rotation angle of the pitch motor, which brings certain challenges to the broken light recovery of the rotating mirror laser tracker.

[0003] The existing rotating mirror laser tracking broken light recovery method uses a monocular camera vision system, installs the monocular camera visual axis and the laser optical axis coaxially, and adjusts the camera visual axis and the laser optical axis to be coaxial by mechanical structure. Due to the difficulty in keeping the two axes strictly coaxial, long-distance broken light recovery fails, so it is necessary to construct a nonlinear relationship model of target mirror distance, target mirror pixel deviation value and tracking recovery servo angle to compensate for the broken light recovery angle calculation. However, this nonlinear model is relatively complex, and the distance parameter of the target mirror is needed to calculate the recovery servo angle. When the distance parameter of the target mirror is unknown, the broken light recovery cannot be performed. In addition, the current machine vision system mainly uses active infrared detection method to identify the target mirror according to the positioning data of the target mirror to calculate the tracking recovery angle. However, this method is easily disturbed by other similar high-brightness light sources in the background, resulting in identification failure, and the identification accuracy of the target mirror will also decrease significantly with the increase of the measurement distance.

[0004] Therefore, how to improve the identification accuracy of the target mirror in a wide range of complex environments and accurately calculate the broken light recovery servo angle when the distance parameter of the target mirror is unknown is a key problem faced by current laser tracking measurement technology. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a rotating mirror binocular vision laser tracking broken light recovery system and method, which avoids the influence of similar interference light sources in complex environments on the identification of the target mirror, solves the problem of accurate calculation of the broken light recovery angle when the distance parameter of the target mirror is unknown, and realizes autonomous laser tracking broken light recovery in a wide range of complex environments.

[0006] The specific technical scheme adopted by the present application to achieve the above-mentioned purpose is:

[0007] One kind is based on the broken light recovery method of the broken light recovery system of two-eye vision laser tracking mirror type, the broken light recovery method includes the following steps:

[0008] S1) when the laser tracker is broken, the infrared light beams emitted by the two infrared illumination light sources in the binocular vision module are modulated, and then a camera corresponding to each infrared illumination light source is used to obtain a target mirror image at the modulation peak and modulation valley of the infrared light beam, a frame difference image of the two target mirror images is obtained, and after image processing, the target mirror position on the camera imaging plane is obtained;

[0009] S2) using the pre-constructed modified virtual imaging plane model, the target mirror position on the virtual imaging plane and the predicted broken light recovery rotation angle are obtained according to the target mirror positions on the imaging planes of the two cameras; the predicted broken light recovery rotation angle includes a predicted azimuth rotation angle and a predicted pitch rotation angle;

[0010] In the step S2, the target mirror position on the virtual imaging plane is obtained by processing the target mirror positions on the imaging planes of the two cameras through the following formula:

[0011] O X =(P LX +P RX ) / 2

[0012] O Y =(P LY +P RY ) / 2

[0013] In the formula, O X , O Y respectively represent the X, Y direction coordinates of the target mirror position on the virtual imaging plane; P LX , P LY respectively represent the X, Y direction coordinates of the target mirror position on the first camera imaging plane, and P RX , P RY respectively represent the X, Y direction coordinates of the target mirror position on the second camera imaging plane.

[0014] In the step S2, the predicted broken light recovery rotation angle is obtained according to the target mirror positions on the imaging planes of the two cameras through the following formula:

[0015]

[0016] In the formula, θ X represents the predicted azimuth rotation angle, θ Y represents the predicted pitch rotation angle, P LX, P LY respectively represent the X, Y direction coordinates of the target mirror position on the first camera imaging plane, P RX , P RY respectively represent the X, Y direction coordinates of the target mirror position on the second camera imaging plane, C X , C Y respectively represent the X, Y direction coordinates of the target mirror zero position on the virtual imaging plane, p represents the distance coefficient from the virtual imaging plane coordinate to the actual measurement space, and f represents the lens focal length of the camera.

[0017] In the step S2, the camera visual axis and the laser optical axis coincide in the corrected virtual imaging plane model. The construction process of the corrected virtual imaging plane model is specifically as follows: a virtual imaging plane model in which the camera visual axis and the laser optical axis coincide is established; the laser beam is aimed at the target mirror, and the target mirror zero position on the virtual imaging plane is calibrated in the virtual imaging plane model; and the inter-axis angle between the virtual imaging plane coordinate and the two-dimensional turntable coordinate of the laser tracker is corrected.

[0018] S3) outputting the target mirror position on the virtual imaging plane obtained in the step S2 to a pre-constructed error model to obtain a corresponding prediction error, and compensating the predicted break light recovery rotation angle obtained in the step S2 through the prediction error to obtain a compensated break light recovery rotation angle; the compensated break light recovery rotation angle includes a compensated azimuth rotation angle and a compensated elevation rotation angle. The step S3 is specifically as follows: inputting the target mirror position on the virtual imaging plane obtained in the step S2 into two linear relationship models in the error model to obtain a corresponding azimuth rotation angle prediction error and an elevation rotation angle prediction error; the two linear relationship models are linear relationship models of the target mirror position on the virtual imaging plane and the azimuth rotation angle prediction error and the elevation rotation angle prediction error; and then using the azimuth rotation angle prediction error and the elevation rotation angle prediction error to compensate the predicted azimuth rotation angle and the predicted elevation rotation angle respectively to obtain the compensated azimuth rotation angle and the compensated elevation rotation angle, and combining to obtain the compensated break light recovery rotation angle.

[0019] The construction process of the error model is specifically as follows:

[0020] 1) aiming the laser beam at the target mirror, and calibrating the target mirror zero position on the virtual imaging plane;

[0021] 2) Control the azimuth motor to step according to the preset step size; after each step, use the angle grating to obtain the actual light break recovery angle, obtain the target mirror position on the imaging plane of the two cameras according to step S1, and then obtain the target mirror position on the virtual imaging plane and the predicted azimuth rotation angle according to step S2; obtain the difference between the actual light break recovery angle and the predicted azimuth rotation angle to obtain the azimuth rotation angle prediction error corresponding to the current position of the target mirror on the virtual imaging plane;

[0022] 3) Use a fitting method to process the azimuth rotation angle prediction errors corresponding to different positions of the target mirror on the virtual imaging plane to obtain a linear relationship model of the target mirror position and the azimuth rotation angle prediction error on the virtual imaging plane;

[0023] 4) Through the same process as steps 2-3, a linear relationship model of the target mirror position and the pitch rotation angle prediction error on the virtual imaging plane is obtained;

[0024] 5) The two linear relationship models obtained in steps 3 and 4 constitute an error model.

[0025] S4) Control the rotating mirror laser tracker according to the compensated light break recovery rotation angle to make the laser beam re-target the target mirror. The step S4 is specifically: drive the azimuth motor to rotate the same angle according to the compensated azimuth rotation angle, and drive the pitch motor to rotate half the angle according to the compensated pitch rotation angle, so that the laser beam can re-target the target mirror.

[0026] II. A rotating mirror binocular vision laser tracking light break recovery system applied to the above light break recovery method

[0027] The light break recovery system comprises a rotating mirror laser tracker and a binocular vision module; the binocular vision module comprises two recognition modules, each recognition module comprising a camera and an infrared illumination light source, and the cameras in the two recognition modules are symmetrically arranged on both sides of the laser optical axis of the rotating mirror laser tracker.

[0028] The rotating mirror type laser tracker comprises a laser ranging module, a pitching motor, an azimuth motor, a tracking rotating mirror and a target mirror; the laser ranging module is used for emitting and receiving a laser beam; an azimuth motor is arranged above the laser ranging module; a pitching motor is installed on the azimuth motor; the azimuth motor and the pitching motor constitute a two-dimensional rotary table; the tracking rotating mirror is installed on the pitching motor; the laser beam emitted by the laser ranging module is reflected by the tracking rotating mirror and then enters the target mirror; the laser beam returned from the target mirror returns to the laser ranging module; two binocular vision modules are symmetrically arranged on both sides of the laser beam emitted by the laser ranging module and are connected with the azimuth motor; an infrared illumination light source in each recognition module emits an infrared light beam, which is reflected by the tracking rotating mirror and the target mirror in turn and then returns to the camera in the recognition module along the original light path and is received by the camera.

[0029] Further, the light interruption recovery system further comprises:

[0030] A data processing main control module, first and second input ends are in communication connection with the two cameras respectively, used for receiving the wave peak mirror image and the wave trough mirror image collected by each camera, after processing by using the corrected virtual imaging plane model and the error model, the compensated light interruption recovery rotation angle is obtained;

[0031] A motor drive control module, an input end is in communication connection with the first output end of the data processing main control module, and an output end is electrically connected with the control ends of the pitching motor and the azimuth motor respectively; used for receiving the compensated light interruption recovery rotation angle from the data processing main control module, and controlling the two motors to rotate by corresponding angles according to the compensated light interruption recovery rotation angle;

[0032] A host computer, used for receiving the compensated light interruption recovery rotation angle from the data processing main control module.

[0033] The beneficial effects of the present application are:

[0034] 1. The two cameras of the binocular vision module are symmetrically installed on both sides of the laser optical axis, a virtual imaging plane model with the camera visual axis coinciding with the laser optical axis is constructed, the light interruption recovery servo angle is calculated according to the two-dimensional offset of the target mirror on the virtual imaging plane, and the problem of the nonlinear change of the monocular vision light interruption recovery servo angle with the distance of the target mirror is avoided;

[0035] 2. The zero point position of the target ball on the virtual imaging plane is calibrated, and the angle between the virtual imaging plane coordinates and the two-dimensional rotary table coordinates of the laser tracker is corrected, so that the coaxial installation precision requirement of the camera visual axis of the vision system is reduced;

[0036] 3、The application constructs a target mirror position error compensation model on a virtual imaging plane decoupled from distance measurement, compensates for the angle error of light interruption recovery caused by the divergence angle of the illumination light source, and realizes accurate calculation of the light interruption recovery angle under the condition that the distance parameter of the target mirror is unknown;

[0037] 4、The application uses binocular vision module data for double confirmation, and uses the average of the binocular vision module data to calculate the rotation angle, thereby improving the target target ball recognition accuracy and the light interruption recovery servo angle calculation accuracy;

[0038] 5、The application modulates the intensity of the infrared illumination light source, acquires a modulated wave trough background image and a modulated wave peak foreground image, uses the foreground and background frame difference image for target mirror recognition, and avoids the influence of similar high-brightness background light sources on target mirror recognition.

[0039] In summary, the application reduces the coaxial installation precision requirement of the vision system of the rotating mirror laser tracker, avoids the influence of similar high-brightness background light sources on target mirror recognition, improves the calculation precision of the light interruption recovery servo angle, and realizes autonomous and rapid light interruption recovery of the rotating mirror laser tracker in a wide range of complex environments. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A rotating mirror binocular vision laser tracking light interruption recovery system schematic diagram related to the example of the embodiment is shown.

[0041] Figure 2 A rotating mirror binocular vision laser tracking light interruption recovery method principle diagram related to the example of the embodiment is shown.

[0042] Figure 3 A rotating mirror binocular vision laser tracking light interruption recovery method azimuth rotation angle and pitch rotation angle calculation principle diagram related to the example of the embodiment is shown.

[0043] Figure 4 A virtual imaging plane coordinate and laser tracker two-dimensional turntable coordinate axis angle model principle diagram related to the example of the embodiment is shown.

[0044] In the figure: 1, laser ranging module, 2, pitch motor, 3, azimuth motor, 4, tracking rotating mirror, 5, target mirror, 6, first camera, 7, second camera, 8, first infrared illumination light source, 9, second infrared illumination light source, 10, data processing main control module, 11, motor drive control module, 12, upper computer. DETAILED DESCRIPTION

[0045] The application will be described in detail below in combination with the drawings and specific embodiments.

[0046] The present application aims to provide a rotating mirror type binocular vision laser tracking broken light recovery system and method, which uses two cameras of a binocular vision system symmetrically installed on both sides of a laser optical axis to construct a virtual imaging plane with the camera optical axis coinciding with the laser optical axis, calculates the broken light recovery servo angle according to the two-dimensional offset of the target mirror on the virtual imaging plane, and avoids the problem of nonlinear change of the monocular vision broken light recovery servo angle with the target mirror distance; constructs a target mirror position error compensation model on the virtual imaging plane for decoupling the measurement distance, compensates for the broken light recovery servo angle error caused by the divergence angle of the illumination light source, and realizes the accurate calculation of the broken light recovery servo angle under the condition that the target mirror distance parameter is unknown; by modulating the intensity of the infrared light source, the modulation valley background image and the modulation peak foreground image are obtained, the target mirror is identified by using the foreground and background frame difference image, the influence of the background similar highlight interference light source on the target mirror identification is avoided, and thus the fast and accurate autonomous laser tracking broken light recovery is realized.

[0047] The present application provides a rotating mirror type binocular vision laser tracking broken light recovery system and method in the first aspect. The present application method reduces the coaxial installation precision requirement of the rotating mirror type laser tracker vision system, avoids the influence of the background similar highlight light source on the target mirror identification, improves the calculation accuracy of the broken light recovery servo angle, and realizes the autonomous and fast broken light recovery of the rotating mirror type laser tracker in a large range of complex environment.

[0048] The present application method comprises the following steps:

[0049] S1) When the rotating mirror type laser tracker is broken, the infrared light beams emitted by the two infrared illumination light sources in the binocular vision module are modulated, and then a camera corresponding to each infrared illumination light source is used to obtain a target mirror image at the modulation peak and the modulation valley of the infrared light beam, the two target mirror images are subtracted to obtain a frame difference image with only the infrared light source irradiation information, and the target mirror position on the camera imaging plane is obtained by image processing the frame difference image.

[0050] In the rotating mirror type binocular vision laser tracking broken light recovery system, in this step, the light beam transmission path is specifically as follows: the first infrared light beam is emitted by the first infrared illumination light source 8, the second infrared light beam is emitted by the second infrared illumination light source 9, after the target mirror 5 receives the first infrared light beam and the second infrared light beam, the first infrared light beam and the second infrared light beam are reflected back, and the first camera 6 and the second camera 7 receive the first infrared light beam and the second infrared light beam reflected by the target mirror 5 respectively.

[0051] In some embodiments, the first infrared illumination light source 8 and the second infrared illumination light source 9 are modulated at the same time. After the laser tracker locks the target mirror, the two infrared light sources stop modulating at the same time.

[0052] In some embodiments, the process of image processing the frame difference image is specifically identifying the target mirror 5 and obtaining its position information.

[0053] In some embodiments, the way of modulating the infrared light beam is modulating the light intensity of the infrared light beam.

[0054] In some embodiments, the way of modulating the light intensity of the infrared light beam is periodically changing the light intensity of the infrared light beam (such as sine wave, square wave).

[0055] In some embodiments, the way of periodically changing the light intensity of the infrared light beam is using a PWM controller to adjust the driving current of the infrared illumination light source.

[0056] S2) Using the pre-constructed corrected virtual imaging plane model, obtaining the target mirror position on the virtual imaging plane according to the target mirror positions on the imaging planes of the two cameras, and then obtaining the predicted broken light recovery rotation angle according to the two-dimensional offset of the target mirror position on the virtual imaging plane.

[0057] Wherein, the two-dimensional offset of the target mirror position on the virtual imaging plane refers to the X direction and Y direction offset of the target mirror position relative to the target mirror zero position on the virtual imaging plane. The target mirror positions on the two camera imaging planes are processed by the following formula to obtain the target mirror position on the virtual imaging plane:

[0058] O X =(P LX +P RX ) / 2

[0059] O Y =(P LY +P RY ) / 2

[0060] In the formula, O X , O Y respectively represent the X and Y direction coordinates of the target mirror position on the virtual imaging plane; P LX , P LY respectively represent the X and Y direction coordinates of the target mirror position on the first camera imaging plane, and P RX , P RY respectively represent the X and Y direction coordinates of the target mirror position on the second camera imaging plane.

[0061] Wherein, the predicted broken light recovery rotation angle includes a predicted azimuth rotation angle and a predicted pitch rotation angle. The obtaining process is specifically: obtaining the predicted broken light recovery rotation angle through the following formula according to the target mirror positions on the imaging planes of the two cameras:

[0062]

[0063] wherein θ X denotes the predicted azimuth rotation angle, θ Y denotes the predicted pitch rotation angle, P LX , P LY denote the target mirror position X, Y direction coordinates on the first camera imaging plane, P RX , P RY denote the target mirror position X, Y direction coordinates on the second camera imaging plane, C X , C Y denote the target mirror zero point position X, Y direction coordinates on the virtual imaging plane, p denotes the virtual imaging plane coordinate to actual measurement space distance coefficient, and f denotes the camera lens focal length (the lens focal lengths of the two cameras are the same).

[0064] In step S2, the camera visual axis and the laser optical axis coincide in the virtual imaging plane model and the corrected virtual imaging plane model. The construction process of the corrected virtual imaging plane model is as follows:

[0065] D1) According to the binocular vision module of the rotating mirror type binocular vision laser tracking light breaking recovery system, the two cameras are symmetrically installed on both sides of the laser optical axis, and a virtual imaging plane model in which the camera visual axis and the laser optical axis coincide is established;

[0066] D2) The laser beam is aligned to the target mirror 5, the target mirror zero point position on the virtual imaging plane is calibrated in the virtual imaging plane model, and the inter-axis angle between the virtual imaging plane coordinate and the laser tracker two-dimensional turntable coordinate is corrected.

[0067] Step D2 is specifically as follows:

[0068] D21) Calibrate the target mirror zero point position: align the laser beam to the target mirror 5, collect the target mirror image by using the binocular vision module, obtain the target mirror positions on the imaging planes of the two cameras according to the target mirror image, and input them into the following formula, and take the target mirror position on the virtual imaging plane obtained as the target mirror zero point position:

[0069] O X =(P LX +P RX ) / 2

[0070] O Y =(P LY +P RY ) / 2

[0071] wherein O X , O Y denote the X, Y direction coordinates of the target mirror position on the virtual imaging plane; P LX , P LYX, Y respectively represent the X, Y direction coordinates of the target mirror position on the first camera imaging plane, P RX RY X, Y respectively represent the X, Y direction coordinates of the target mirror position on the second camera imaging plane.

[0072] D22) Correct the inter-axis angle between the virtual imaging plane coordinates and the two-dimensional turntable coordinates of the laser tracker: control the azimuth motor 3 in the two-dimensional turntable to rotate around the horizontal axis, and obtain the change amount of the target mirror position along the Y direction on the virtual imaging plane at different target mirror position X direction coordinates, and then correct the inter-axis angle in the X direction according to the change amount, so that the target mirror position coordinate in the Y direction remains unchanged when the azimuth motor 3 rotates. According to the same method, control the pitch motor 2 in the two-dimensional turntable to rotate around the vertical axis, and obtain the change amount of the target mirror position along the X direction in the virtual imaging plane model at different target mirror position Y direction coordinates, and then correct the inter-axis angle in the Y direction, so that the target mirror position coordinate in the X direction remains unchanged when the pitch motor 2 rotates.

[0073] Wherein, the change amount of the target mirror position along the Y direction on the virtual imaging plane is obtained by the following process: after each rotation, the current position of the target mirror on the virtual imaging plane is obtained according to the target mirror image collected by the binocular vision module in the same way as step D21, and then the change amount of the target mirror position along the Y direction on the virtual imaging plane at the current target mirror position X direction coordinate is obtained in combination with the target mirror zero position.

[0074] S3) Output the target mirror position on the virtual imaging plane obtained in step S2 to the error model constructed in advance to obtain the corresponding prediction error, and compensate the predicted break light recovery rotation angle by the prediction error to obtain the compensated break light recovery rotation angle; this step is used to compensate the prediction error of the break light recovery rotation angle caused by the illumination light divergence angle. The prediction error includes azimuth rotation angle prediction error and pitch rotation angle prediction error. The compensated break light recovery rotation angle includes compensated azimuth rotation angle and compensated pitch rotation angle.

[0075] ​In step S3, the compensation process is specifically: the error model comprises a linear relationship model between the target mirror position on the virtual imaging plane and the azimuth rotation angle prediction error, and a linear relationship model between the target mirror position on the virtual imaging plane and the pitch rotation angle prediction error; the target mirror position on the virtual imaging plane obtained in step S2 is input into the two linear relationship models respectively to obtain the corresponding azimuth rotation angle prediction error and the pitch rotation angle prediction error; the azimuth rotation angle prediction error and the pitch rotation angle prediction error are used to compensate the predicted azimuth rotation angle and the predicted pitch rotation angle respectively to obtain the compensated azimuth rotation angle and the compensated pitch rotation angle, and the compensated ocular recovery rotation angle is obtained by combination.

[0076] The construction process of the error model is specifically:

[0077] 1) The laser beam is aligned to the target mirror 5, and the zero position of the target mirror on the virtual imaging plane is calibrated;

[0078] 2) The azimuth motor 3 is controlled to step according to a preset step size; after each step, the actual ocular recovery angle is obtained by using an angle grating, the target mirror positions on the imaging planes of the two cameras are obtained through step S1, and the target mirror position on the virtual imaging plane and the predicted azimuth rotation angle are obtained through step S2; the difference between the actual ocular recovery angle and the predicted azimuth rotation angle is obtained to obtain the azimuth rotation angle prediction error corresponding to the current target mirror position on the virtual imaging plane;

[0079] 3) The azimuth rotation angle prediction errors corresponding to different positions of the target mirror on the virtual imaging plane are processed by using a fitting method to obtain a linear relationship model between the target mirror position on the virtual imaging plane and the azimuth rotation angle prediction error;

[0080] 4) Through the same process as steps 2-3, a linear relationship model between the target mirror position on the virtual imaging plane and the pitch rotation angle prediction error is obtained;

[0081] 5) The two linear relationship models obtained in steps 3 and 4 constitute the error model.

[0082] S4) The target mirror 5 is re-aligned by the laser beam according to the compensated ocular recovery rotation angle. Step S4 is specifically: the azimuth motor 3 in the two-dimensional turntable is driven to rotate by the same angle according to the compensated azimuth rotation angle in the compensated ocular recovery rotation angle, the pitch motor 2 in the two-dimensional turntable is driven to rotate by half the angle according to the compensated pitch rotation angle in the compensated ocular recovery rotation angle, and finally the laser beam is re-aligned to the target mirror 5.

[0083] The second aspect of the present application provides a rotating mirror type binocular vision laser tracking light break recovery system applied to the above-mentioned light break recovery method. The rotating mirror type binocular vision laser tracking light break recovery system comprises a rotating mirror type laser tracker and a binocular vision module; the binocular vision module comprises two recognition modules, each of which comprises a camera and an infrared illumination light source, and the cameras in the two recognition modules are symmetrically arranged on both sides of the laser optical axis of the rotating mirror type laser tracker. The camera optical axis is reflected to the working area together with the laser optical axis through the tracking mirror of the rotating mirror type laser tracker.

[0084] The rotating mirror type laser tracker comprises a laser ranging module 1, a pitch motor 2, an azimuth motor 3, a tracking rotating mirror 4 and a target mirror 5; the laser ranging module 1 is used for emitting and receiving a laser beam, the azimuth motor 3 is arranged above the laser ranging module 1, the pitch motor 2 is installed on the azimuth motor 3 and can drive the pitch motor 2 to rotate around a horizontal axis, and the azimuth motor 3 and the pitch motor 2 constitute a two-dimensional turntable; the tracking rotating mirror 4 is installed on the pitch motor 2 and can drive the tracking rotating mirror 4 to rotate synchronously and pitch, i.e. rotate around a vertical axis, and the laser beam emitted by the laser ranging module 1 is reflected by the tracking rotating mirror 4 and then enters the target mirror 5, and the laser beam returned from the target mirror 5 returns to the laser ranging module 1 along the original light path; the infrared illumination light source in each recognition module emits an infrared light beam, which is reflected by the tracking rotating mirror 4 and the target mirror 5 in turn and then returns to the collection end of the camera in the recognition module to which the infrared illumination light source belongs and is received by the camera; the two binocular vision modules are symmetrically arranged on both sides of the laser beam emitted by the laser ranging module 1, and the two binocular vision modules are connected with the output end of the azimuth motor 3 and rotate with the azimuth motor 3.

[0085] In addition, the light break recovery system further comprises:

[0086] A data processing main control module 10, the first input end and the second input end are respectively in communication connection with the two cameras, for receiving the wave peak mirror image and the wave trough mirror image collected by each camera, and after processing using the corrected virtual imaging plane model and the error model, the compensated light break recovery rotation angle is obtained;

[0087] A motor drive control module 11, the input end is in communication connection with the first output end of the data processing main control module 10, and the output end is respectively in electrical connection with the control end of the pitch motor 2 and the azimuth motor 3; for receiving the compensated light break recovery rotation angle from the data processing main control module 10, and controlling the two motors to rotate by a corresponding angle according to the compensated light break recovery rotation angle;

[0088] A host computer 12, for receiving the compensated light break recovery rotation angle from the data processing main control module 10.

[0089] Further, the host computer 12 can be used to perform storage, visualization, data processing and other operations on the compensated light break recovery rotation angle.

[0090] The specific implementation of the present application is as follows:

[0091] As Figure 1 shown, the rotating mirror type binocular vision laser tracking broken light recovery system used in this embodiment includes a laser ranging module 1, a pitch motor 2, an azimuth motor 3, a tracking rotating mirror 4, a target mirror 5, a first camera 6, a second camera 7, a first infrared illumination light source 8, a second infrared illumination light source 9, a data processing host module 10, a motor drive control module 11, and an upper computer 12.

[0092] The laser ranging module 1, the pitch motor 2, the azimuth motor 3, the tracking rotating mirror 4, and the target mirror 5 constitute a rotating mirror type laser tracker. The laser ranging module 1 is fixed and does not rotate with the two-dimensional rotary table composed of the pitch motor 2 and the azimuth motor 3. The tracking rotating mirror 4 is fixed on the pitch motor 2 and rotates with it. The laser ranging module 1 emits a laser beam, which is reflected by the tracking rotating mirror 4 and then enters the target mirror 5. The laser beam returned from the target mirror 5 returns to the laser ranging module 1, realizing target tracking and spatial coordinate measurement.

[0093] The first camera 6, the second camera 7, the first infrared illumination light source 8, and the second infrared illumination light source 9 are fixed on the azimuth motor 3 and rotate with it. The first camera 6 and the second camera 7 are symmetrically installed on both sides of the laser beam emitted by the laser ranging module 1. The first infrared illumination light source 8 and the second infrared illumination light source 9 are installed around the first camera 6 and the second camera 7, respectively, so that the first infrared beam and the second infrared beam reflected back by the target mirror 5 react to a uniform target mirror spot profile.

[0094] The target mirror images collected by the first camera 6 and the second camera 7 are processed by the data processing host module 10 to obtain the compensated azimuth rotation angle θ X ’ and the compensated pitch rotation angle θ Y ’, and are sent to the motor drive control module 11. The motor drive control module 11 is used to control the azimuth motor 3 to rotate by an angle of θ X ’ and control the pitch motor 2 to rotate by an angle of θ Y ’ / 2, so that the laser beam of the laser tracker is re-aligned with the target mirror 5, and the broken light recovery is completed. The data processing host module 10 interacts with the upper computer 12.

[0095] As Figure 2 shown, the rotating mirror type binocular vision broken light recovery model used in this embodiment includes a target mirror 5, a laser optical axis M, a first camera optical axis M1, a second camera optical axis M2, an X direction X, a Y direction Y, a target mirror zero point position C on a virtual imaging plane, a target mirror current position O on the virtual imaging plane, a target mirror current position O1 on a first camera imaging plane, a target mirror current position O2 on a second camera imaging plane, a first camera imaging center P1, a second camera imaging center P2, and a first camera and second camera imaging center connecting line midpoint R.

[0096] Adjust the first camera view axis M1 and the second camera view axis M2 parallel to the laser axis M, and symmetric relative to the laser axis M, so that the midpoint R of the line connecting the first camera imaging center P1 and the second camera imaging center P2 is located on the laser axis M. When the laser beam M is aligned with the target mirror 5, the zero point position C of the target mirror on the virtual imaging plane is calibrated. When the laser beam M deviates from the target mirror 5, the current position O1 of the target mirror on the first camera imaging plane can be obtained on the first camera 6, and the current position O2 of the target mirror on the second camera imaging plane can be obtained on the second camera 7. The current position O of the target mirror on the virtual imaging plane can be obtained from the current position O1 of the target mirror on the first camera imaging plane and the current position O2 of the target mirror on the second camera imaging plane based on the geometric relationship, and the specific formula is:

[0097] O X =(P LX +P RX ) / 2

[0098] O Y =(P LY +P RY ) / 2

[0099] Where O X and O Y are the X-direction and Y-direction coordinates of the target mirror position O on the virtual imaging plane. P LX and P LY are the X-direction and Y-direction coordinates of the current position O1 of the target mirror on the first camera imaging plane, and P RX and P RY are the X-direction and Y-direction coordinates of the current position O2 of the target mirror on the second camera imaging plane.

[0100] As shown in FIG. 1, the azimuth rotation angle and the pitch rotation angle prediction model in the rotating mirror type binocular vision laser tracking discontinuity recovery method adopted in the embodiment includes the target mirror 5, the laser axis M, the zero point position C of the target mirror on the virtual imaging plane, the current position O of the target mirror on the virtual imaging plane, the midpoint R of the line connecting the imaging centers of the first camera and the second camera, the azimuth rotation angle θ X , the pitch rotation angle θ Y , the X-direction target mirror offset d X , and the Y-direction target mirror offset d Y .

[0101] The X-direction target mirror offset d X and the Y-direction target mirror offset d Y are obtained from the current position O of the target mirror on the virtual imaging plane and the zero point position C of the target mirror on the virtual imaging plane, respectively.Y Then calculate the predicted azimuth rotation angle θ X And predict pitch and rotation angle θ Y The specific formula is as follows:

[0102] The predicted azimuth rotation angle is:

[0103] The predicted pitch and rotation angle is:

[0104] Among them, C X and C Y Let C represent the coordinates of the target zero point position C on the virtual imaging plane in the X and Y directions, respectively; p is the distance coefficient from the calibrated virtual imaging plane coordinates to the actual measured space; and f is the focal length of the lenses of the first and second cameras.

[0105] like Figure 4 As shown, the angle correction model between the virtual imaging plane coordinates and the coordinate axes of the two-dimensional turntable of the laser tracker in this embodiment includes the target mirror 5 and the virtual imaging plane X direction D. XR Virtual imaging plane Y direction D YR The position of the target mirror on the virtual imaging plane is in D. YR The deviation D from the zero point position of the target mirror in the direction, and the position O of the target mirror after angle compensation. C Interaxial angle α E R is the midpoint of the line connecting the imaging centers of the first and second cameras.

[0106] To correct the interaxial angle α E The resulting deviation in the position of the light spot is controlled by the azimuth motor 3, which moves the imaging point of the target mirror 5 from point C along the X direction until the imaging point is located at the edge of the image. Imaging point O X Coordinates and zero point C X Coordinates in the Y direction of the virtual imaging plane D YR The deviation on is D; D varies with O X Linear transformation of coordinates:

[0107] D=K D ×(O X -C X )

[0108] Among them, K D Let be a coefficient. Then, when moving in the X direction, the deviation ΔY of the imaging point in the Y direction can be calculated as:

[0109] ΔY=cosa E ×K D ×(O X -C X )

[0110] Interaxial angle a E is a small enough angle, then cos a E may be considered as 1. The compensated Y direction coordinate is O YC :

[0111] O YC = O Y + ΔY

[0112] Similarly, the control of the pitch motor 2 rotates, and the deviation of the target mirror position in the X direction is compensated to obtain O XC .

[0113] The principle of the model for compensating the prediction error of the rotation angle of the broken light recovery caused by the divergence angle of the illumination light in this embodiment is as follows: when the irradiation angle of the infrared light beam on the target mirror 5 is zero, the target mirror position O on the virtual imaging plane coincides with the actual imaging point O R of the target mirror; when the irradiation angle of the infrared light beam on the target mirror 5 is not zero, there is a deviation d R between the target mirror position O on the virtual imaging plane and the actual imaging point O I of the target mirror 5, and the deviation d I is positively correlated with the irradiation angle I and is independent of the distance of the target mirror 5. The deviation d I causes an error between the predicted rotation angle of the broken light recovery and the actual rotation angle of the broken light recovery θ. The error has a linear relationship with the target mirror position O on the virtual imaging plane, and therefore an error model is established for compensation.

[0114] In this embodiment, the specific implementation steps of the rotation mirror type binocular vision laser tracking broken light recovery method are as follows:

[0115] 1) Establish a virtual imaging plane model in which the camera visual axis coincides with the laser optical axis: in the rotation mirror type binocular vision laser tracking broken light recovery system, the two cameras of the binocular vision module are symmetrically installed on both sides of the laser optical axis M, the first camera visual axis M1 and the second camera visual axis M2 after reflection by the tracking rotation mirror 4 are centrally symmetric relative to the reflected laser optical axis M, and the intersection of the first camera visual axis M1 and the second camera visual axis M2 is located at infinity; based on camera calibration and imaging principles, a virtual imaging plane model in which the camera visual axis coincides with the laser optical axis is constructed by using the geometric relationship between the two camera visual axes and the laser optical axis M.

[0116] 2) Calibrate the target ball zero position on the virtual imaging plane, and correct the interaxial angle between the virtual imaging plane coordinates and the laser tracker two-dimensional turntable coordinates;

[0117] The correction of the interaxial angle between the virtual imaging plane coordinates and the laser tracker two-dimensional turntable coordinates in step 2) is as follows: in order to correct the interaxial angle a EThe position deviation of the light spot caused, the azimuth motor 3 controls the target mirror 5 to move the imaging point from point C along the X direction until the imaging point is located at the image edge. The imaging point O X The coordinate of the zero point C X The deviation of the coordinate on the virtual imaging plane Y direction D YR is D; D is proportional to O X The coordinate changes linearly:

[0118] D=K D ×(O X -C X )

[0119] In the formula, K D is a coefficient. Then when moving in the X direction, the deviation of the imaging point in the Y direction ΔY can be calculated as:

[0120] ΔY=cosa E ×K D ×(O X -C X )

[0121] The inter-axis angle a E is a small enough angle, then cos a E can be considered as 1. Then the Y direction coordinate after compensation is O YC :

[0122] O YC =O Y +ΔY

[0123] Similarly, the pitch motor 2 is controlled to rotate, and the deviation of the target mirror position in the X direction is compensated to obtain O XC .

[0124] 3) By modulating the infrared light source of the binocular vision system, target mirror images are obtained at the modulation wave peak and the modulation wave valley respectively, and the two images are subtracted to obtain a frame difference image with only infrared light source illumination information. The frame difference image is processed to identify the target mirror and obtain its position information;

[0125] In step 3), the identification and position information acquisition of the target mirror by the binocular vision module are as follows:

[0126] The system emits a first infrared light beam through the first infrared illuminating light source 8 and a second infrared light beam through the second infrared illuminating light source 9. After receiving the first infrared light beam and the second infrared light beam, the target mirror 5 reflects the first infrared light beam and the second infrared light beam back along the original path. The first camera 6 and the second camera 7 of the binocular vision module receive the reflected first infrared light beam and the second infrared light beam respectively.

[0127] The first infrared illumination light source 8 and the second infrared illumination light source 9 are modulated respectively, the first camera 6 acquires foreground images and background images respectively when the modulation wave is at a wave crest and a wave trough, a frame difference image is obtained after the foreground images and the background images are subtracted, and the target mirror position O1 carried by the first infrared light beam is obtained after the frame difference image is processed; similarly, the target mirror position O2 carried by the second infrared light beam is obtained after the second camera frame difference image is processed;

[0128] 4) According to the target mirror positions on the imaging planes of the two cameras, the target mirror positions on a virtual imaging plane are obtained, a predicted break light recovery rotation angle is calculated according to two-dimensional offset amounts, and the predicted break light recovery rotation angle is compensated in combination with an error model;

[0129] In step 4), the process of obtaining the break light recovery rotation angle is specifically as follows:

[0130] On the virtual imaging plane where the camera visual axis coincides with the laser light axis, the target mirror position X direction coordinate is (P LX +P RX ) / 2, and the target mirror position Y direction coordinate is (P LY +P RY ) / 2, wherein P LX and P RX respectively represent the target mirror position X direction coordinates of the imaging planes of the first camera 6 and the second camera 7, and P LY and P RY respectively represent the target mirror position Y direction coordinates of the imaging planes of the first camera and the second camera;

[0131] The predicted azimuth rotation angle is:

[0132] The predicted pitch rotation angle is:

[0133] Wherein, C X and C Y respectively represent the target mirror zero point position C on the virtual imaging plane X direction coordinate and Y direction coordinate on the virtual imaging plane, p is a virtual imaging plane coordinate to actual measurement space distance coefficient of calibration, and f is a lens focal length of the first camera and the second camera;

[0134] In step 4), the compensation of the predicted error according to the error model of the target mirror position on the imaging plane is specifically as follows:

[0135] When the laser beam is aimed at the target mirror 5, the zero position C of the target mirror on the virtual imaging plane is calibrated, the precise angle reading of the angle grating of the laser tracker is used to control the precise angle stepping of the motor, the error between the predicted light break recovery rotation angle and the stepping angle is obtained, a linear relationship model of the target mirror position and the prediction error is constructed, and the prediction error of the light break recovery rotation angle caused by the divergence angle of the illumination light is compensated.

[0136] 5) Drive the corresponding rotation mechanism to rotate the corresponding light break recovery angle, so that the laser beam is re-aligned with the target mirror 5.

[0137] In step 5), driving the corresponding rotation mechanism to rotate the corresponding light break recovery angle is specifically as follows: driving the azimuth motor 3 to rotate θ X ’ angle. Since the laser beam tilt rotation angle of the rotating mirror laser tracker is twice the tilt motor rotation angle, the tilt motor is driven to rotate θ Y ’ / 2 angle, so that the laser beam is tilted by θ Y ’ angle, and finally the laser beam is re-aligned with the target mirror. Wherein, θ X ’ and θ Y ’ represent the compensated azimuth rotation angle and the compensated tilt rotation angle respectively.

[0138] The above specific embodiments are used to explain and illustrate the present application, rather than limit the present application. Any modifications and changes made to the present application within the spirit and protection scope of the claims fall within the protection scope of the present application.

Claims

1. A method for break recovery based on a break recovery system of a rotating mirror binocular vision laser tracking, characterized in that, The method comprises the following steps: S1) When the laser tracker is interrupted, the infrared beams emitted by the two infrared illuminators in the binocular vision module are modulated, and then a camera corresponding to each infrared illuminator is used to obtain a target mirror image at the modulation peak and the modulation trough of the infrared beam respectively, a frame difference image of the two target mirror images is obtained, and after image processing, the position of the target mirror on the camera imaging plane is obtained; S2) Using a pre-constructed corrected virtual imaging plane model, the position of the target mirror on the virtual imaging plane and the predicted interrupted light recovery rotation angle are obtained according to the positions of the target mirror on the imaging planes of the two cameras; the predicted interrupted light recovery rotation angle comprises a predicted azimuth rotation angle and a predicted elevation rotation angle; S3) The position of the target mirror on the virtual imaging plane obtained in step S2 is output to the pre-constructed error model to obtain the corresponding predicted error, and the predicted interrupted light recovery rotation angle obtained in step S2 is compensated by the predicted error to obtain the compensated interrupted light recovery rotation angle; The compensated interrupted light recovery rotation angle comprises a compensated azimuth rotation angle and a compensated elevation rotation angle; S4) The compensated interrupted light recovery rotation angle is used to control the rotary mirror laser tracker, so that the laser beam is re-aligned with the target mirror (5).

2. The light loss recovery method of claim 1, wherein: In step S2, the position of the target mirror on the virtual imaging plane is obtained by processing the positions of the target mirror on the imaging planes of the two cameras according to the following formula: O X = (P LX + P RX ) / 2 O Y = (P LY + P RY ) / 2 In the formula, O X , O Y respectively represent the X, Y direction coordinates of the target mirror position on the virtual imaging plane; P LX , P LY respectively represent the X, Y direction coordinates of the target mirror position on the first camera imaging plane, P RX , P RY respectively represent the X, Y direction coordinates of the target mirror position on the second camera imaging plane.

3. The light loss recovery method of claim 1, wherein: In step S2, the predicted interrupted light recovery rotation angle is obtained by the following formula: wherein θ X denotes the predicted azimuth rotation angle, θ Y denotes the predicted pitch rotation angle, P LX , P LY denote the target mirror position X, Y direction coordinates on the first camera imaging plane, P RX , P RY denote the target mirror position X, Y direction coordinates on the second camera imaging plane, C X , C Y denote the target mirror zero point position X, Y direction coordinates on the virtual imaging plane, p denotes the virtual imaging plane coordinate to actual measurement space distance coefficient of calibration, and f denotes the camera lens focal length.

4. The optical recovery method of claim 1, wherein: In step S2, in the corrected virtual imaging plane model, the camera visual axis coincides with the laser optical axis; the construction process of the corrected virtual imaging plane model is as follows: a virtual imaging plane model in which the camera visual axis coincides with the laser optical axis is established; the laser beam is aligned with the target mirror (5), and the zero point position of the target mirror on the virtual imaging plane is calibrated in the virtual imaging plane model; and the inter-axle angle between the virtual imaging plane coordinates and the two-dimensional rotary table coordinates of the laser tracker is corrected.

5. The optical recovery method of claim 1, wherein: Step S3 is specifically: the position of the target mirror on the virtual imaging plane obtained in step S2 is input into two linear relationship models in the error model respectively to obtain the corresponding azimuth rotation angle prediction error and elevation rotation angle prediction error; the two linear relationship models are linear relationship models of the position of the target mirror on the virtual imaging plane and the azimuth rotation angle prediction error and the elevation rotation angle prediction error; The azimuth rotation angle prediction error and the elevation rotation angle prediction error are used to compensate the predicted azimuth rotation angle and the predicted elevation rotation angle respectively to obtain the compensated azimuth rotation angle and the compensated elevation rotation angle, and the compensated interrupted light recovery rotation angle is obtained by combination.

6. The optical recovery method of claim 1, wherein: The construction process of the error model is specifically as follows: 1) The laser beam is aligned with the target mirror (5), and the zero point position of the target mirror on the virtual imaging plane is calibrated; 2) The azimuth motor (3) is controlled to step according to a preset step size; After each step, the actual angle of recovery of the broken light is obtained by using an angle grating, the positions of the target mirror on the imaging planes of the two cameras are obtained according to step S1, and the position of the target mirror on the virtual imaging plane and the predicted azimuth rotation angle are obtained according to step S2; The difference between the actual angle of recovery of the broken light and the predicted azimuth rotation angle is obtained to obtain the azimuth rotation angle prediction error corresponding to the current position of the target mirror on the virtual imaging plane; 3) The azimuth rotation angle prediction errors corresponding to different positions of the target mirror on the virtual imaging plane are processed by using a fitting method to obtain a linear relationship model of the position of the target mirror and the azimuth rotation angle prediction error on the virtual imaging plane; 4) Through the same process as steps 2-3, a linear relationship model of the position of the target mirror and the pitch rotation angle prediction error on the virtual imaging plane is obtained; 5) The two linear relationship models obtained in steps 3 and 4 constitute an error model.

7. The optical recovery method of claim 1, wherein: The step S4 is specifically: driving the azimuth motor (3) to rotate by the same angle according to the compensated azimuth rotation angle, and driving the pitch motor (2) to rotate by half the angle according to the compensated pitch rotation angle, so that the laser beam can be re-aligned with the target mirror (5).

8. A rotating mirror binocular visual laser tracking light recovery system applied to the light recovery method as claimed in any one of claims 1 to 7, characterized in that: The laser tracking device comprises a rotating mirror type laser tracker and a binocular vision module; the binocular vision module comprises two recognition modules, each recognition module comprising a camera and an infrared illumination light source, and the cameras in the two recognition modules are symmetrically arranged on both sides of the laser optical axis of the rotating mirror type laser tracker.

9. The rotating-mirror binocular vision laser tracking break-recovery system of claim 8, wherein: The rotating mirror type laser tracker comprises a laser ranging module (1), a pitch motor (2), an azimuth motor (3), a tracking rotating mirror (4) and a target mirror (5); the laser ranging module (1) is used for emitting and receiving a laser beam, an azimuth motor (3) is arranged above the laser ranging module (1), a pitch motor (2) is installed on the azimuth motor (3), and the azimuth motor (3) and the pitch motor (2) constitute a two-dimensional turntable; the tracking rotating mirror (4) is installed on the pitch motor (2), the laser beam emitted by the laser ranging module (1) is reflected by the tracking rotating mirror (4) and then enters the target mirror (5), and the laser beam returned from the target mirror (5) returns to the laser ranging module (1); the two binocular vision modules are symmetrically arranged on both sides of the laser beam emitted by the laser ranging module (1) and are connected with the azimuth motor (3); the infrared illumination light source in each recognition module emits an infrared light beam, which is reflected by the tracking rotating mirror (4) and the target mirror (5) in turn and then returns to the camera in the recognition module along the original light path and is received by the camera.

10. The wobble mirror binocular vision laser tracking break recovery system of claim 9, wherein, Further comprising: a data processing main control module (10), a first input end and a second input end are in communication connection with the two cameras respectively, for receiving the wave peak mirror image and the wave valley mirror image collected by each camera, and obtaining the compensated broken light recovery rotation angle after processing by using the corrected virtual imaging plane model and the error model; a motor drive control module (11), an input end is in communication connection with a first output end of the data processing main control module (10), and an output end is in electrical connection with control ends of the pitch motor (2) and the azimuth motor (3) respectively; The data processing master module (10) is used for receiving the compensated broken light recovery rotation angle from the data processing master module (10), and controlling the two motors to rotate corresponding angles according to the compensated broken light recovery rotation angle. The upper computer (12) is used for receiving the compensated broken light recovery rotation angle from the data processing master module (10).

Images