CN104315995B - TOF depth camera three-dimensional coordinate calibration device and method based on virtual multi-cube standard target - Google Patents

Abstract

The invention relates to a TOF depth camera three-dimensional coordinate calibration device and method based on a virtual multi-cube standard target, including a three-dimensional motion translation platform, a TOF depth camera, a cube target and a background plate; the calibration method utilizes three mutually orthogonal one-dimensional The motion translation platform produces several movements in the three-dimensional direction. By designing a reasonable movement mode, a virtual multi-cube standard target with complex shapes and multiple feature points is formed, and the spatial position and three-dimensional measurement coordinates of the corner points of the target can be accurately obtained. Realize high-precision three-dimensional coordinate calibration of TOF depth cameras. The present invention greatly reduces the difficulty and measurement error of a single TOF depth camera in recognizing target corner features, improves the three-dimensional measurement accuracy of the TOF depth camera, and can flexibly set the corner position and number of feature points of a virtual multi-cube standard target , It is easy to realize the high-precision automatic calibration of the whole process.

Description

Three-dimensional coordinate calibration device for TOF depth camera based on virtual multi-cube standard target setting and method

technical field

The invention belongs to the technical field of optical metrology and calibration, and in particular relates to a calibration device and method for a non-scanning laser three-dimensional TOF (Time-of-Flight) depth camera based on a virtual multi-cube standard target.

Background technique

With the continuous improvement and improvement of optical measurement and computer vision technology, the development of advanced manufacturing technology and the diversification of product requirements, the demand for measurement of three-dimensional shape information on the surface of complex objects continues to increase, which promotes the continuous development of optical three-dimensional measurement technology and has become One of the main fields and directions of optical metrology and information optics.

As a new generation of optical three-dimensional measurement technology, the TOF depth camera can obtain the grayscale information of space objects and the depth information corresponding to each pixel in real time, which is different from traditional laser three-dimensional scanning imaging, binocular stereo vision and three-dimensional imaging systems based on structured light. Compared with TOF depth cameras, it has the advantages of good real-time performance, moderate measurement accuracy, small size, and light weight.

In order to eliminate the systematic error caused by the inconsistency between the space coordinate system and the measurement coordinate system, the three-dimensional coordinate calibration is a crucial step in the high-precision optical three-dimensional measurement of the TOF depth camera, mainly by obtaining the three-dimensional space of the standard object target Characteristic parameters, and then obtain the coordinate transformation relationship from the three-dimensional measurement coordinates of the TOF depth camera to the space coordinates to complete the calibration of the three-dimensional coordinates. Therefore, the high-precision extraction and recognition of the spatial position and shape parameters of the selected standard object is an important guarantee for the high-precision three-dimensional measurement of the TOF depth camera, and the standard target used for calibration of the TOF depth camera should fill the entire field of view in order to obtain the TOF depth The three-dimensional coordinate calibration results of the center and edge of the camera field of view, resulting in various calibration methods for TOF depth cameras, mainly in the following two categories:

(1) TOF depth camera calibration method based on planar markers, such as checkerboard calibration method (1. Zhengyou, Zhang. A flexible new technique for camera calibration. Technical Report MSR-TR-98-71, Microsoft Research. 1998.2. Li Xingdong, Chen Chao, Li Mantian, Sun Lining. Time-of-Flight 3D Camera Calibration and Error Compensation. Mechanics and Electronics. 2013(11): 37-40; 3. Pan Huadong. Mechanism and Characteristics of Time-of-Flight 3D Imaging Camera Without Scanning .PhD dissertation of Zhejiang University. 2010.04; 4. Patent 201210021469.4 "3D Registration Method Based on TOF Depth Camera"; 5.Young Min Kim, Derek Chan, Christian Theobalt, Sebastian Thrun.Design and Calibration of a Multi-view TOFSensor Fusion System .Computer Vision and Pattern Recognition Workshops,2008.CVPRW'08.IEEE Computer Society Conference.June 23-28,2008.Anchorage,AK; 6.Stefan Fuchs,Gerd Hirzinger.Extrinsic and Depth Calibration of TOF-cameras.Computer Vision and Pattern Recognition, 2008. CVPR 2008. IEEEConference. June 23-28, 2008. Anchorage, AK; 7. Sung-Yeol Kim, Woon Cho, Andreas Koschan, and Mongi A. Abidi. Depth Data Calibration and Enhancement of Time-of-flight Video-plus-Depth Camera. Future of Instrumentation International Workshop (FIIW). November 7-8, 2011. Oak Ridge, TN; 8. Marvin Lindner, Ingo Schiller, Andreas Kolb, Reinhard K och.Time-of-Flight Sensor Calibration for AccurateRange Sensing.Computer Vision and Image Understanding.2010(114):1318-1328; 9.Miles Hansard,Radu Horaud,Michel Amat,Georgios Evangelidis.Automatic Detection of Calibration Grids in Time-of -flight Images.Computer Vision and Image Understanding.2014(121):108-118) or using the dot array calibration method (1. Cai Hui. Research on Camera Calibration and 3D Reconstruction Method in Vision Measurement. Harbin Institute of Technology Master's Degree Thesis .2013.07; 2.Jiyoung Jung, Yekeun Jeong, Jaesik Park, Hyowon Ha, James Dokyoon Kim, and In-SoKweon. A Novel 2.5D Pattern for Extrinsic Calibration of ToF and Camera FusionSystem. 2011IEEE/RSJ International Conference on Intelligent Robots and Systems. September 25-30, 2011. San Francisco, CA, USA; 3. Frederic Garcia, Djamila Aouada, Bruno Mirbach, and Ottersten. Real-Time Distance-Dependent Mapping for a Hybrid ToF Multi-Camera Rig. IEEE JOURNAL OF SELECTED TOPICS IN SIGNALPROCESSING, 2012.6 (5): 425-436), these methods are used for black and white planar checkerboard graphics placed at multiple angles ( or dot array graphics) to take multiple shots, and then calculate the positions of each corner point at different angle positions of the checkerboard (or the center position of each dot in the dot array), and then realize the calibration of the TOF depth camera according to the spatial coordinate transformation relationship , this method has high calibration accuracy and is widely used, but the number of acquisitions is large, the data processing process is complicated, and the extraction errors of multiple corner points will be directly accumulated in the final calibration result, and it is difficult to further improve the calibration accuracy, which directly affects Three-dimensional measurement accuracy of TOF depth camera;

(2) The TOF depth camera calibration method based on the complex feature three-dimensional markers, such as using three-dimensional objects with different depth features such as cubes or multi-layer steps as the standard measurement object for the TOF depth camera calibration method (1.Tsai, R.A versatile camera calibration technique for high-accuracy 3D machinevision metrology using off-the-shelf TV cameras and lenses.IEEE Journal of Robotics and Automation.1987.RA-3(4):323-344; 2. Xu De, Tan Min, Li Yuan . Robot Vision Measurement and Control. National Defense Industry Press. 2011.05; 3. Filiberto Chiabrando, Roberto Chiabrando, DarioPiatti, Fulvio Rinaudo. Sensors for 3D Imaging: Metric Evaluation and Calibration of a CCD/CMOS Time-of-Flight Camera. Sensors.2009 (9):10080-10096; 4. Stuart Robson, J.-Angelo Beraldin, Andrew Brownhill and Lindsay MacDonald. Artefacts for Optical Surface Measurement. Proc. of SPIE Vol.8085, Videometrics, Range Imaging, and Applications XI, 80850C.May23 ,2011.Munich,Germany; 5. Patent 201210352365.1 "Three-dimensional measurement method based on computer vision cube calibration"), although these methods can directly collect different depth information at different positions on the surface of complex features, and then calculate the TOF The measurement error of the depth camera is compensated, but due to the need to extract and identify the complex features acquired at the same time, the calculation is large and the extraction error will be accumulated in the final calibration result. The three-dimensional coordinate calibration accuracy and three-dimensional measurement accuracy of the TOF depth camera It is also difficult to improve further.

From the above analysis, it can be seen that in practical applications, the currently widely used calibration methods of TOF depth cameras have the following shortcomings: the number of target features that appear in the field of view in a single acquisition of TOF depth cameras is large, making The data processing process is long, and the complexity of target recognition and feature extraction is high, which directly leads to the accumulation of measurement errors in target recognition and feature extraction into the 3D coordinate calibration results of the TOF 3D camera, which greatly affects the accuracy of the TOF depth camera calibration results And repeatability, thus limiting the application range of TOF depth cameras, this is the shortcoming of the existing calibration scheme itself, and it is also an important problem that the current TOF depth cameras cannot solve in practical applications.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the above-mentioned existing TOF depth camera calibration scheme, and provide a TOF depth camera three-dimensional coordinate calibration device and method based on a virtual multi-cube standard target. The calibration device includes a three-dimensional motion translation platform, a TOF Depth camera, cube target and background plate; the calibration method uses three one-dimensional motion translation platforms orthogonal to each other to move in three orthogonal directions of X, Y, and Z. By designing a reasonable movement mode, the combination of a single cube target in the field of view of the TOF depth camera at each movement position forms a virtual multi-cube standard target with complex shapes and multiple feature points, and obtains the three-dimensional space of the corner point features of the target The coordinate transformation relationship of the three-dimensional coordinate calibration can be obtained by the position and the measurement coordinates, and the three-dimensional coordinate calibration of the TOF depth camera can be realized. The present invention greatly reduces the difficulty and measurement error of a single TOF depth camera for target corner feature recognition, effectively improves the three-dimensional coordinate calibration and measurement accuracy of the TOF depth camera, and can flexibly set the corner position and feature points of a virtual standard cube number, and it is easy to realize the automatic calibration of the whole process.

The technical solution adopted in the present invention is: a TOF depth camera three-dimensional coordinate calibration device based on a virtual multi-cube standard target, including a three-dimensional motion translation platform, a TOF depth camera, a cube target and a background plate. Among them, the connection mode of the three-dimensional motion translation platform is that three one-dimensional movement translation platforms are connected in pairs in three-dimensional directions; the TOF depth camera is fixed on the movement translation platform, and performs three-dimensional movement together with the three-dimensional movement translation platform; the background plate is The plane plate is perpendicular to the optical axis of the TOF depth camera, and the cube target is fixed on the background plate; the three-dimensional motion translation stage is used to generate several movements in the three-dimensional direction to form a virtual multi-cube standard target with complex shape and multiple feature points.

The present invention also provides a method for calibrating the three-dimensional coordinates of a TOF depth camera based on a virtual multi-cube standard target. The method includes the following steps:

(1) First determine the coordinate system OXYZ of the TOF depth camera. The three translation axes of the three-dimensional translation stage are defined as the three directions of X, Y, and Z. The coordinate origin O is positioned as the lens center of the TOF depth camera. The installation bottom surface of the three-dimensional motion translation stage is defined as The XZ plane is parallel to the bottom surface of the TOF depth camera; the Z direction is the optical axis direction of the TOF depth camera, which is parallel to the movement direction of the translation axis of the translation platform in the Z direction; the Y direction is the vertical direction of the bottom surface of the three-dimensional motion translation platform; the X direction is the right-hand coordinate The direction defined by the system; the three-dimensional coordinate conversion relationship between the space coordinate system OXYZ and the TOF depth camera three-dimensional measurement coordinate system OcXcYcZc is as follows:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ {\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cccc}{\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ {\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]$

Among them, x _c , y _c , z _c represent the coordinates of any point on the cube target in the three-dimensional measurement coordinate system of the TOF depth camera, x _w , y _w , z _w represent the coordinates of the point in the space coordinate system OXYZ, nx _x , nx _y , nx _z represent the direction vector of the X-axis of the space coordinate system in the three-dimensional measurement coordinate system of the TOF depth camera, ny _x , ny _y , ny _z represent the direction of the Y-axis of the space coordinate system in the three-dimensional measurement coordinate system of the TOF depth camera Vector, nz _x , nz _y , nz _z represent the direction vector of the Z axis of the space coordinate system in the TOF depth camera three-dimensional measurement coordinate system, p _x , p _y , p _z represent the coordinate origin of the space coordinate system in the TOF depth camera three-dimensional measurement Coordinates in the coordinate system;

(2) Adjust the initial positions of the TOF depth camera and the cube target so that the end face of the cube target is in close contact with the lens surface of the TOF depth camera, and ensure that the optical axis of the TOF depth camera lens passes through the center of the cube target;

(3) Control the movement in the Z direction. The translation platform drives the TOF depth camera to move along the Z direction, and produces precise displacement in the Z direction. When it reaches the determined position sz in the Z direction, the movement in the Z direction is completed;

(4) Control the X-direction movement translation platform and the Y-direction movement translation platform, drive the TOF depth camera at the sz position, and perform traversal movement in the XY plane to form a virtual multi-cube standard target; each position in the movement in the XY plane , the spatial position coordinates of the four corners of the top surface of the cube target can be uniquely determined by the length and width of the cube target and the motion position of the moving translation platform, as shown in the following formula:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Among them, i (i=1,2,3,...) and j (j=1,2,3,...) are the position numbers of the TOF depth camera moving in the X direction and the Y direction in the XY plane respectively; Pij1( xij1, yij1, zij1), Pij2 (xij2, yij2, zij2), Pij3 (xij3, yij3, zij3), Pij4 (xij4, yij4, zij4) are the four corner points of the top surface of the cube target in the space coordinate system OXYZ sxij is the precise displacement of the translation platform moving in the X direction in the X direction; syij is the precise displacement of the translation platform moving in the Y direction in the Y direction; sz is the precise displacement of the translation platform moving in the Z direction in the Z direction; L and W are the length and width of the cube target, respectively.

(5) The TOF depth camera performs three-dimensional measurement on the cube target, and obtains the three-dimensional measurement coordinate values of the four corner points on the top surface of the cube target, that is, the coordinates of the four corner points in the TOF depth camera three-dimensional measurement coordinate system OcXcYcZc are respectively : Pij1'(xij1',yij1',zij1'), Pij2'(xij2',yij2',zij2'), Pij3'(xij3',yij3',zij3'), Pij4'(xij4',yij4',zij4 ');

(6) Traverse the entire XY plane, and obtain the spatial positions and three-dimensional coordinate measurement values of the corner points of the cube object at all XY positions at the Z direction position. Bringing into the above three-dimensional coordinate conversion relationship, the calibration of the three-dimensional coordinates of the TOF depth camera can be realized by solving the linear equations.

The present invention has following characteristics and good effect:

(1) The present invention makes full use of the mutually orthogonal three-axis high-precision motion translation platform to generate several movements in the three-dimensional direction, and a single target in the field of view of the TOF depth camera at each movement position is combined to form a complex shape and feature Point virtual multi-cube standard target, which is one of the innovations different from the existing TOF depth camera three-dimensional coordinate calibration technology;

(2) In the present invention, there is only one target in the field of view of the TOF depth camera at each moving position, and the background is simple, so that the data processing process of each TOF depth camera for target recognition and extraction is simple, and the accuracy of simple targets can be achieved. Corner feature extraction and recognition greatly reduces the difficulty and recognition error of target feature extraction and recognition, which is the second innovation point different from the existing TOF depth camera calibration technology;

(3) The present invention constructs a standard target with a complex shape and multiple feature points composed of a virtual multi-cube by adopting the three-dimensional motion of a mutually orthogonal three-dimensional high-precision motion translation platform. At different positions of the TOF depth camera field of view, Obtain the three-dimensional measurement results and the three-dimensional space position of the target, so that the three-dimensional coordinate calibration of the TOF depth camera can be calculated, which meets the needs of the three-dimensional coordinate calibration of the TOF depth camera, reduces the recognition error of complex target features, and improves the three-dimensional coordinates of the TOF depth camera The calibration accuracy reduces the system error introduced by the mismatch between the spatial coordinate system and the measurement coordinate system, thereby improving the three-dimensional measurement accuracy of the TOF depth camera, and the measurement process and data processing are significantly simplified, and it is easy to achieve full automatic calibration. powerful.

Description of drawings

Fig. 1 is the structural representation of device of the present invention;

Fig. 2 is a structural schematic diagram of a mutually orthogonal three-dimensional motion translation stage and a TOF depth camera in the device of the present invention;

Fig. 3 is a schematic diagram of the imaging of the target in the field of view of the TOF depth camera when the moving translation platform 3 * 3 moves in the present invention;

Fig. 4 is the structural representation of the virtual multi-cube standard target formed after the motion translation platform 3 * 3 moves in the present invention;

Fig. 5 is a schematic diagram of the spatial position coordinates of the corner points of the virtual multi-cube standard target in the XY plane in the present invention.

detailed description

The TOF depth camera calibration device and method based on the virtual multi-cube standard target of the present invention will be described in detail below in conjunction with the figures and embodiments:

As shown in Figure 1, the device of the present invention is composed of a Z-direction moving translation stage 1, an X-direction moving translation stage 2, a Y-direction moving translation stage 3, a TOF depth camera 4, a cube target 5, and a background plate 6. Among them: as shown in Figure 2, the connection mode of the X-direction motion translation platform 2, the Y-direction movement translation platform 3 and the Z-direction movement translation platform 1 is two-two orthogonal connection in the three-dimensional direction of space, and the movement direction of the Z-direction movement translation platform 1 Parallel to the optical axis direction of the TOF depth camera 4, the TOF depth camera 4 is fixed on the Y-direction motion translation platform 3, the installation bottom surface of the TOF depth camera 4 is parallel to the installation bottom surface of the Z-direction movement translation platform, and the TOF depth camera 4 moves with the three The translation platform performs three-dimensional movement together; the background plate 6 is a flat plate, which is perpendicular to the optical axis of the TOF depth camera 4 , and the cube target 5 is fixed on the background plate 6 .

The method described in the present invention is described in detail below:

(1) First determine the TOF depth camera 4 coordinate system OXYZ, the three translation axes of the three-dimensional translation stage are defined as the three directions of X, Y, and Z, the coordinate origin O is positioned as the lens center of the TOF depth camera 4, and the three-dimensional motion translation stage is installed The bottom surface is defined as the XZ plane, which is parallel to the bottom surface of the TOF depth camera 4; the Z direction is the optical axis direction of the TOF depth camera 4, which is parallel to the movement direction of the translation axis of the Z-direction translation platform 1; the Y direction is the vertical direction of the installation bottom surface of the three-dimensional motion translation platform ; The X direction is the direction defined by the right-hand coordinate system; the three-dimensional coordinate conversion relationship between the space coordinate system OXYZ and the TOF depth camera 4 three-dimensional measurement coordinate system OcXcYcZc is as follows:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ {\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cccc}{\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ {\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]$

Among them, x _c , y _c , z _c represent the coordinates of any point on the cube target 5 in the three-dimensional measurement coordinate system of the TOF depth camera 4, x _w , y _w , z _w represent the coordinates of the point in the space coordinate system OXYZ, nx _x , nx _y , nx _z represent the direction vector of the X-axis of the space coordinate system in the TOF depth camera 4 three-dimensional measurement coordinate system, ny _x , ny _y , ny _z represent the Y-axis of the space coordinate system in the TOF depth camera 4 three-dimensional measurement coordinates The direction vector under the system, nz _x , nz _y , nz _z represent the direction vector of the Z axis of the space coordinate system in the TOF depth camera 4 three-dimensional measurement coordinate system, p _x , p _y , p _z represent the coordinate origin of the space coordinate system at Coordinates in the TOF depth camera 4 three-dimensional measurement coordinate system;

(2) Adjust the initial positions of the TOF depth camera 4 and the cube target 5 so that the end face of the cube target 5 is in close contact with the lens surface of the TOF depth camera 4, and ensure that the lens optical axis of the TOF depth camera 4 passes through the center of the cube target;

(3) Control the movement of the translation platform 1 in the Z direction to drive the TOF depth camera 4 to move along the Z direction, generate precise displacement in the Z direction, and reach the determined position sz in the Z direction, and the movement in the Z direction is completed;

(4) Control the X-direction movement translation platform 2 and the Y-direction movement translation platform 3, drive the TOF depth camera 4 at the sz position, and perform traversal movement in the XY plane to form a virtual multi-cube standard target; each movement in the XY plane position, the four corner position coordinates of the cube target 5 top surfaces can be uniquely determined by the length and width of the cube target 5 and the motion positions of the three motion translation platforms, as shown in the following formula:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Among them, i (i=1,2,3,...) and j (j=1,2,3,...) are the position numbers of the TOF depth camera 4 moving in the X direction and the Y direction in the XY plane respectively; Pij1 (xij1, yij1, zij1), Pij2 (xij2, yij2, zij2), Pij3 (xij3, yij3, zij3), Pij4 (xij4, yij4, zij4) are the four corner points of the top surface of the cube target 5 in the space coordinate system Coordinates under OXYZ; sxij is the precise displacement of the X direction motion translation platform 2 in the X direction; syij is the precise displacement of the Y direction movement translation platform 3 in the Y direction; sz is the Z direction movement translation platform 1 in the Z direction. Precise displacement; L and W are the length and width of the cube target 5, respectively.

(5) The TOF depth camera 4 performs three-dimensional measurement on the cube target 5, and obtains the three-dimensional measurement coordinate values of the four corner points on the top surface of the cube target 5, that is, the four corner points are under the three-dimensional measurement coordinate system OcXcYcZc of the TOF depth camera 4 The coordinates are: Pij1'(xij1',yij1',zij1'), Pij2'(xij2',yij2',zij2'), Pij3'(xij3',yij3',zij3'), Pij4'(xij4', yij4', zij4');

(6) Traverse the entire XY plane to obtain the spatial positions and three-dimensional measurement coordinate values of the 5 corner points of the cube target at all XY positions in the Z direction at this time, bring them into the above-mentioned coordinate conversion relationship, and solve the linear equations to realize the The three-dimensional coordinate calibration of the TOF depth camera 4 completes the entire calibration process.

It can be seen that by using the three-dimensional motion of the mutually orthogonal three-axis high-precision motion translation platform, a standard target with complex shapes and multiple feature points composed of virtual multi-cubes is constructed. At different positions of the TOF depth camera 4 field of view, The three-dimensional measurement results and the precise three-dimensional space position of the target are calculated to complete the three-dimensional coordinate calibration, which meets the needs of the three-dimensional coordinate calibration of the TOF depth camera 4, reduces the recognition error of complex target features, and improves the three-dimensional coordinate calibration accuracy of the TOF depth camera 4. Moreover, the measurement process and data processing are significantly simplified, and it is easy to realize full-scale automatic calibration, and has strong practicability.

Example 1:

(1) Taking the TOF depth camera 4 at a distance of 0.5m, the combination of the X-direction moving translation platform 2 and the Y-direction moving translation platform 3 to carry out 3×3 movement in the XY plane as an example, describe in detail the calibration device introduced in the present invention and Methods as below:

As shown in Figure 1, first determine the TOF depth camera 4 coordinate system OXYZ, the three translation axes of the three-dimensional translation platform are defined as the three directions of X, Y, and Z, and the coordinate origin O is positioned as the lens center of the TOF depth camera 4, and the three-dimensional movement The bottom surface of the translation stage is defined as the XZ plane, which is parallel to the bottom surface of the TOF depth camera 4; the Z direction is the optical axis direction of the TOF depth camera 4, which is parallel to the movement direction of the translation axis of the translation stage 1 in the Z direction; the Y direction is the bottom surface of the three-dimensional motion translation stage The vertical direction; the X direction is the direction defined by the right-hand coordinate system; the three-dimensional coordinate conversion relationship between the space coordinate system OXYZ and the TOF depth camera 4 three-dimensional measurement coordinate system OcXcYcZc is as follows:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ {\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cccc}{\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; nx</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; nz</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ {\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]$

Among them, x _c , y _c , z _c represent the coordinates of any point on the cube target 5 in the three-dimensional measurement coordinate system of the TOF depth camera 4, x _w , y _w , z _w represent the coordinates of the point in the space coordinate system OXYZ, nx _x , nx _y , nx _z represent the direction vector of the X-axis of the space coordinate system in the TOF depth camera 4 three-dimensional measurement coordinate system, ny _x , ny _y , ny _z represent the Y-axis of the space coordinate system in the TOF depth camera 4 three-dimensional measurement coordinates The direction vector under the system, nz _x , nz _y , nz _z represent the direction vector of the Z axis of the space coordinate system in the TOF depth camera 4 three-dimensional measurement coordinate system, p _x , p _y , p _z represent the coordinate origin of the space coordinate system at Coordinates in the TOF depth camera 4 three-dimensional measurement coordinate system;

(2) Adjust the initial positions of the TOF depth camera 4 and the cube target 5 so that the end face of the cube target 5 is in close contact with the lens surface of the TOF depth camera 4, and ensure that the lens optical axis of the TOF depth camera 4 passes through the center of the cube target;

(3) Control the movement of the translation platform 1 in the Z direction to drive the TOF depth camera 4 to move along the Z direction to produce a precise displacement in the Z direction and reach the determined position sz=0.5m in the Z direction, and the movement in the Z direction is completed;

(4) Control the X-direction movement translation platform 2 and the Y-direction movement translation platform 3, drive the TOF depth camera 4 at the sz position, and perform traversal movement in the XY plane. When moving, the top surface of the cube target 5 is viewed by the TOF depth camera 4 The schematic diagram of imaging in the field is shown in Figure 3, and the schematic diagram of forming a virtual multi-cube standard target is shown in Figure 4, which produces accurate reference displacements in the X and Y directions; The position coordinates of the four corners can be uniquely determined by the length and width of the cube target 5 and the motion positions of the three moving translation platforms. The spatial position coordinates of the corner points of the virtual multi-cube standard target in the XY plane are shown in Figure 5, as follows The formula shows:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; xij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; yij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; zij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Pij</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sxij</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; syij</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; sz</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Among them, i (i=1,2,3,...) and j (j=1,2,3,...) are the position numbers of the TOF depth camera 4 moving in the X direction and the Y direction in the XY plane respectively; Pij1 (xij1, yij1, zij1), Pij2 (xij2, yij2, zij2), Pij3 (xij3, yij3, zij3), Pij4 (xij4, yij4, zij4) are the four corner points of the top surface of the cube target 5 in the space coordinate system Coordinates under OXYZ; sxij is the precise displacement of the X direction motion translation platform 2 in the X direction; syij is the precise displacement of the Y direction movement translation platform 3 in the Y direction; sz is the Z direction movement translation platform 1 in the Z direction. Precise displacement; L and W are the length and width of the cube target 5, respectively.

(5) The TOF depth camera 4 performs three-dimensional measurement on the cube target 5, and obtains the three-dimensional measurement coordinate values of the four corner points on the top surface of the cube target 5, that is, the four corner points are under the three-dimensional measurement coordinate system OcXcYcZc of the TOF depth camera 4 The coordinates are: Pij1'(xij1',yij1',zij1'), Pij2'(xij2',yij2',zij2'), Pij3'(xij3',yij3',zij3'), Pij4'(xij4', yij4', zij4');

(6) Traverse the entire XY plane to obtain the spatial positions and three-dimensional measurement coordinate values of a total of 36 corner points of the cube target 5 at the position in the Z direction at this time, bring them into the above-mentioned coordinate conversion relationship, and solve the linear equations to realize TOF The three-dimensional coordinate calibration of the depth camera 4 completes the entire calibration process.

In this embodiment, the translation stage 2 moving in the X direction, the translation stage 3 moving in the Y direction, and the translation stage 1 moving in the Z direction all adopt high-precision electronically controlled translation stages, and the positioning accuracy is better than 0.05mm. Among them, the translation stage 2 moving in the X direction The stroke is better than 2m, the stroke of Y-direction moving translation platform 3 is better than 1m, and the stroke of Z-direction moving translation platform 1 is better than 0.4m; the three-dimensional measurement distance of TOF depth camera 4 is 0.5m~5m, the three-dimensional measurement accuracy is ±10mm, and the cube target 5 is a cube target with a side length of 150 mm. Since the positioning accuracy of the electronically controlled translation stage is much higher than the measurement accuracy of the TOF depth camera 4, the positioning error of the moving translation stage itself can be ignored. The calibration experiment results show that the entire measurement process is fully automated, and the measurement accuracy of the TOF depth camera calibrated by the calibration method provided by the present invention is improved from ±10mm to better than 6.85mm, realizing the automation of the TOF depth camera with high precision and three-dimensional calibration.

Example 2:

As shown in FIG. 1 , the cube target 5 is in the shape of a cuboid whose length, width and height are not exactly equal. The other components and working principles of this embodiment are the same as those of Embodiment 1.

The above embodiments are provided only for the purpose of describing the present invention, not to limit the scope of the present invention. The scope of the invention is defined by the appended claims. Various equivalent replacements and modifications made without departing from the spirit and principle of the present invention shall fall within the scope of the present invention.

Claims (6)

1. a kind of tof depth camera three-dimensional coordinate caliberating device based on virtual many cubes standard target, including three-dimensional motion Translation stage, tof depth camera, cubic objects and background board it is characterised in that: the connection side of described three-dimensional motion translation stage Formula is that three motion in one dimension translation stages combine connection in three-dimensional pairwise orthogonal, and tof depth camera is fixed on three-dimensional motion and puts down In moving stage, carry out three-dimensional motion with three-dimensional motion translation stage, background board is surface plate, hang down with the optical axis of tof depth camera Directly, cubic objects are fixed on background board；Produce the motion several times on three-dimensional using three-dimensional motion translation stage, constitute One virtual many cubes standard target with complicated shape and multi-characteristic points；Calibration process is as follows:

(1) determine tof depth camera coordinate system oxyz first, three translation shafts of D translation platform are defined as three sides of x, y, z To, zero o orientates tof depth camera optical center as, and three-dimensional motion translation stage is installed bottom surface and is defined as xz plane, with It is parallel that tof depth camera installs bottom surface；Z direction is tof depth camera optical axis direction, with z direction translation stage translation shaft motion side To parallel；The vertical direction of bottom surface is installed for three-dimensional motion translation stage in y direction；The direction that x direction defines for right-handed coordinate system；Empty Between the following institute of three-dimensional coordinate transformational relation between coordinate system oxyz and tof depth camera three-dimensional measurement coordinate system ocxcyczc Show:

$\left[\begin{array}{c}{x}_c\\ y_c\\ z_c\\ 1\end{array}\right]=\left[\begin{array}{cccc}{\mathrm{nx}}_x& {\mathrm{ny}}_x& {\mathrm{nz}}_x& p_x\\ {\mathrm{nx}}_y& {\mathrm{ny}}_y& {\mathrm{nz}}_y& p_y\\ {\mathrm{nx}}_z& {\mathrm{ny}}_z& {\mathrm{nz}}_z& p_z\\ 0& 0& 0& 1\end{array}\right]\left[\begin{array}{c}{x}_w\\ y_w\\ z_w\\ 1\end{array}\right]$

Wherein, x_c, y_c, z_cRepresent coordinate under tof depth camera three-dimensional measurement coordinate system for any point on cubic objects, x_w, y_w, z_wRepresent this coordinate under space coordinates oxyz, nx_x, nx_y, nx_zRepresentation space coordinate system x-axis is in tof depth Direction vector under camera three-dimensional measurement coordinate system, ny_x, ny_y, ny_zRepresentation space coordinate system y-axis is in the three-dimensional survey of tof depth camera Direction vector under amount coordinate system, nz_x, nz_y, nz_zRepresentation space coordinate system z-axis is under tof depth camera three-dimensional measurement coordinate system Direction vector, p_x, p_y, p_zSeat under tof depth camera three-dimensional measurement coordinate system for the zero of representation space coordinate system Mark；

(2) initial position of adjustment tof depth camera and cubic objects is so that cubic objects end face and tof depth camera Camera lens surface is close to, and ensures that tof depth camera camera lens optical axis pass through cubic objects center；

(3) control z direction motion translation platform to drive tof depth camera movable in the z-direction, produce z direction precise displacement, reach At z orientation determining location sz, the motion of z direction completes；

(4) control x direction motion translation platform and y direction motion translation platform, drive tof depth camera at sz position, put down in xy Carry out coverage motion in face, form virtual many cubes standard target；At each position in moving in x/y plane, cube Four feature angle point position coordinateses of target top surface can be by the fortune of the length and width of cubic objects and motion translation platform Dynamic position uniquely determines, is shown below:

$\left\{\begin{array}{c}pij1(xij1,yij1,zij1)=pij1(sxij+l/2,syij+w/2,sz)\\ pij2(xij2,yij2,zij2)=pij2(sxij-l/2,syij+w/2,sz)\\ pij3(xij3,yij3,zij3)=pij3(sxij-l/2,syij-w/2,sz)\\ pij4(xij4,yij4,zij4)=pij4(sxij+l/2,syij-w/2,sz)\end{array}\right.$

Wherein, the position number of i and j respectively tof depth camera x direction and the motion of y direction in x/y plane, i=1,2, 3 ... ..., j=1,2,3 ... ...；pij1(xij1,yij1,zij1)、pij2(xij2,yij2,zij2)、pij3(xij3, Yij3, zij3), pij4 (xij4, yij4, zij4) be respectively cubic objects top surface four angle points in space coordinates oxyz Under coordinate；The precise displacement that sxij moves in x direction for x direction motion translation platform；Syij is y direction motion translation platform in y The precise displacement of direction motion；The precise displacement that sz moves in z direction for z direction motion translation platform；L and w is respectively cube The length and width of target；

(5) tof depth camera carries out three-dimensional measurement to cubic objects, obtains four corner location of cubic objects top surface Three-dimensional measurement coordinate figure is it may be assumed that four angle points coordinate under tof depth camera three-dimensional measurement coordinate system ocxcyczc is respectively as follows: pij1’(xij1’,yij1’,zij1’)、pij2’(xij2’,yij2’,zij2’)、pij3’(xij3’,yij3’,zij3’)、 pij4’(xij4’,yij4’,zij4’)；

(6) travel through whole x/y plane, obtain the locus of cubic objects angle point at all of xy position at this z direction position With three-dimensional coordinate measurement value, bring in above-mentioned three-dimensional coordinate transformational relation, solution system of linear equations is realized to tof depth camera The demarcation of three-dimensional coordinate.

2. device according to claim 1 it is characterised in that: the cube number of described virtual many cubes standard target And cubic site is determined by the three-dimensional motion combination of three-dimensional motion translation stage.

3. device according to claim 1 it is characterised in that: described three-dimensional motion translation stage adopt electronic control translation stage realize Three-dimensional motion.

4. device according to claim 1 it is characterised in that: described cubic objects are the equal square mesh of the length of side Mark.

5. device according to claim 1 it is characterised in that: described cubic objects are the length that length, width and height are not completely equivalent Cube target.

6. a kind of tof depth camera three-dimensional coordinate scaling method based on virtual many cubes standard target is it is characterised in that institute The scaling method stated comprises the following steps:

(1) determine tof depth camera coordinate system oxyz first, three translation shafts of D translation platform are defined as three sides of x, y, z To, zero o orientates tof depth camera optical center as, and three-dimensional motion translation stage is installed bottom surface and is defined as xz plane, with It is parallel that tof depth camera installs bottom surface；Z direction is tof depth camera optical axis direction, with z direction translation stage translation shaft motion side To parallel；The vertical direction of bottom surface is installed for three-dimensional motion translation stage in y direction；The direction that x direction defines for right-handed coordinate system；Empty Between the following institute of three-dimensional coordinate transformational relation between coordinate system oxyz and tof depth camera three-dimensional measurement coordinate system ocxcyczc Show:

$\left[\begin{array}{c}{x}_c\\ y_c\\ z_c\\ 1\end{array}\right]=\left[\begin{array}{cccc}{\mathrm{nx}}_x& {\mathrm{ny}}_x& {\mathrm{nz}}_x& p_x\\ {\mathrm{nx}}_y& {\mathrm{ny}}_y& {\mathrm{nz}}_y& p_y\\ {\mathrm{nx}}_z& {\mathrm{ny}}_z& {\mathrm{nz}}_z& p_z\\ 0& 0& 0& 1\end{array}\right]\left[\begin{array}{c}{x}_w\\ y_w\\ z_w\\ 1\end{array}\right]$

Wherein, x_c, y_c, z_cRepresent coordinate under tof depth camera three-dimensional measurement coordinate system for any point on cubic objects, x_w, y_w, z_wRepresent this coordinate under space coordinates oxyz, nx_x, nx_y, nx_zRepresentation space coordinate system x-axis is in tof depth Direction vector under camera three-dimensional measurement coordinate system, ny_x, ny_y, ny_zRepresentation space coordinate system y-axis is in the three-dimensional survey of tof depth camera Direction vector under amount coordinate system, nz_x, nz_y, nz_zRepresentation space coordinate system z-axis is under tof depth camera three-dimensional measurement coordinate system Direction vector, p_x, p_y, p_zSeat under tof depth camera three-dimensional measurement coordinate system for the zero of representation space coordinate system Mark；

(2) initial position of adjustment tof depth camera and cubic objects is so that cubic objects end face and tof depth camera Camera lens surface is close to, and ensures that tof depth camera camera lens optical axis pass through cubic objects center；

(3) control z direction motion translation platform to drive tof depth camera movable in the z-direction, produce z direction precise displacement, reach At z orientation determining location sz, the motion of z direction completes；

(4) control x direction motion translation platform and y direction motion translation platform, drive tof depth camera at sz position, put down in xy Carry out coverage motion in face, form virtual many cubes standard target；At each position in moving in x/y plane, cube Four feature angle point position coordinateses of target top surface can be by the fortune of the length and width of cubic objects and motion translation platform Dynamic position uniquely determines, is shown below:

$\left\{\begin{array}{c}pij1(xij1,yij1,zij1)=pij1(sxij+l/2,syij+w/2,sz)\\ pij2(xij2,yij2,zij2)=pij2(sxij-l/2,syij+w/2,sz)\\ pij3(xij3,yij3,zij3)=pij3(sxij-l/2,syij-w/2,sz)\\ pij4(xij4,yij4,zij4)=pij4(sxij+l/2,syij-w/2,sz)\end{array}\right.$

Wherein, the position number of i and j respectively tof depth camera x direction and the motion of y direction in x/y plane, i=1,2, 3 ... ..., j=1,2,3 ... ...；pij1(xij1,yij1,zij1)、pij2(xij2,yij2,zij2)、pij3(xij3, Yij3, zij3), pij4 (xij4, yij4, zij4) be respectively cubic objects top surface four angle points in space coordinates oxyz Under coordinate；The precise displacement that sxij moves in x direction for x direction motion translation platform；Syij is y direction motion translation platform in y The precise displacement of direction motion；The precise displacement that sz moves in z direction for z direction motion translation platform；L and w is respectively cube The length and width of target；

(5) tof depth camera carries out three-dimensional measurement to cubic objects, obtains four corner location of cubic objects top surface Three-dimensional measurement coordinate figure is it may be assumed that four angle points coordinate under tof depth camera three-dimensional measurement coordinate system ocxcyczc is respectively as follows: pij1’(xij1’,yij1’,zij1’)、pij2’(xij2’,yij2’,zij2’)、pij3’(xij3’,yij3’,zij3’)、 pij4’(xij4’,yij4’,zij4’)；

(6) travel through whole x/y plane, obtain the locus of cubic objects angle point at all of xy position at this z direction position With three-dimensional coordinate measurement value；Bring in above-mentioned three-dimensional coordinate transformational relation, solution system of linear equations is realized to tof depth camera The demarcation of three-dimensional coordinate.