CN104315995A - 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. The device comprises a three-dimensional motion horizontally-moving platform, a TOF depth camera, a cubical target and a background board. The calibration method includes the steps that three orthometric one-dimensional motion horizontally-moving platforms move repeatedly in the three-dimensional direction, the virtual multi-cube standard target of a complex shape and with multiple feature points is formed, the space position and the three-dimensional measured coordinates of a target angular point can be accurately obtained, and high-precision three-dimensional coordinate calibration of the TOF depth camera is achieved. By means of the TOF depth camera three-dimensional coordinate calibration device and method, target angular point feature recognition difficulty of the TOF depth camera and measurement errors each time are greatly reduced, three-dimensional measurement precision of the TOF depth camera is improved, the angular point position and the number of feature points of the virtual multi-cube standard target can be set flexibly, and full-process high-precision automatic calibration is achieved easily.

Description

Based on TOF depth camera three-dimensional coordinate caliberating device and the method for virtual many cubes standard target

Technical field

The invention belongs to optical metrology and calibration technique field, particularly a kind of caliberating device of no-raster laser three-D TOF (Time-of-Flight) depth camera based on virtual many cubes standard target and method.

Background technology

Along with improvement day by day and the lifting of optical measurement and computer vision technique, the development of advanced manufacturing technology and the measurement demand of the variation of product demand to the three-dimensional appearance information on complex object surface constantly increase, impel optical three-dimensional measurement technology development, become one of the major domain and direction of optical metrology and information optics.

As the optical three-dimensional measurement technology of a new generation, TOF depth camera can the half-tone information of Real-time Obtaining extraterrestrial target and depth information corresponding to each pixel, 3-D imaging system with traditional laser three-dimensional scanning imaging, binocular stereo vision and structure based light is compared, TOF depth camera has the advantages such as real-time is good, measuring accuracy is moderate, volume is little, lightweight, is applied to rapidly the field such as the navigation of mobile robot and map building, space rover, industrial processes manufacture.

In order to eliminate the systematic error because the inconsistency between space coordinates and surving coordinate system causes, it is that TOF depth camera carries out a vital step in high-precision optical three-dimensional measurement that three-dimensional coordinate is demarcated, mainly by obtaining the three dimensions characteristic parameter of standard item target, and then try to achieve TOF depth camera three-dimensional measurement coordinate completes three-dimensional coordinate demarcation to the coordinate conversion relation of volume coordinate.Thus, the locus of the standard item chosen and the extracted with high accuracy of form parameter are the important guarantees that TOF depth camera carries out high precision three-dimensional measurement with identifying, and the standard target of TOF depth camera calibration and usage should be full of whole visual field, just can obtain the three-dimensional coordinate calibration result at TOF depth camera field of view center and edge, thereby produce the various scaling method to TOF depth camera, mainly contain following two classes:

(1) the TOF depth camera based on plane marker demarcates mode, as adopted tessellated demarcation mode (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 method three-dimensional camera is demarcated and error compensation. machinery and electronics .2013 (11): 37-40, 3. Pan East China. the mechanism of time-of-flight method no-raster three-dimensional imaging video camera and characteristic research. Zhejiang University Ph.D. Dissertation .2010.04, 4. patent 201210021469.4 " three-dimensional registration method based on TOF depth camera ", 5.Young Min Kim, Derek Chan, Christian Theobalt, Sebastian Thrun.Design and Calibration of a Multi-view TOF Sensor 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.IEEE Conference.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 Koch.Time-of-Flight Sensor Calibration for Accurate Range 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 adopt dot matrixes demarcation mode (1. Cai Hui. the camera calibration in vision measurement and three-dimensional rebuilding method are studied. Harbin Institute of Technology master thesis .2013.07, 2.Jiyoung Jung, Yekeun Jeong, Jaesik Park, Hyowon Ha, James Dokyoon Kim, and In-So Kweon.A Novel 2.5D Pattern for Extrinsic Calibration of ToF and Camera Fusion System.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 SIGNAL PROCESSING, 2012.6 (5): 425-436), these methods are repeatedly taken the chequered with black and white plane chessboard pattern (or dot matrixes figure) that multiple angle is placed, then each corner location (or each round dot center of dot matrixes) at tessellated Difference angles place is calculated, again according to the demarcation of space coordinate transformation relational implementation to TOF depth camera, the method stated accuracy is higher, apply comparatively extensive, but times of collection is many, data handling procedure is complicated, and will directly be accumulated in final calibration result to the extraction error of multiple angle point, stated accuracy is difficult to further raising, and then directly affect the three-dimensional measurement precision of TOF depth camera,

(2) the TOF depth camera based on complex characteristic stereo marker demarcates mode, the stereoscopic articles such as the cubic block having different depth feature as adopted or multilayer steps carry out the scaling method (1.Tsai, R.A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses.IEEE Journal of Robotics and Automation.1987.RA-3 (4): 323-344 of TOF depth camera as canonical measure object; 2. Xu De, Tan Min, Li Yuan. robot vision Measurement & Control. National Defense Industry Press .2011.05; 3.Filiberto Chiabrando, Roberto Chiabrando, Dario Piatti, 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 " method for three-dimensional measurement based on computer vision cube is demarcated "), although these methods directly can collect the different depth information at diverse location place in complex characteristic object plane type, and then resolve the measuring error obtaining TOF depth camera and compensate, but owing to needing to extract the complex characteristic collected and identify simultaneously, calculated amount is large and extraction error will be accumulated in final calibration result, and three-dimensional coordinate stated accuracy and the three-dimensional measurement precision of TOF depth camera are also difficult to further raising.

Analyzed as can be seen from above, in actual applications, all there is following weak point in the scaling method of the TOF depth camera extensively adopted at present: the target signature quantity that TOF depth camera appears at when single acquisition in visual field is more, make data handling procedure long, target identification and feature extraction complexity high, the measuring error accumulation that directly results in target identification and feature extraction thus enters in the three-dimensional coordinate calibration result of TOF three-dimensional camera, greatly affect accuracy and the repeatability of TOF depth camera calibration result, thus limit the range of application of TOF depth camera, this is the weak point of current existing scaling scheme itself, also be current TOF depth camera unsolved major issue in actual applications.

Summary of the invention

The object of the invention is to overcome the deficiency existed in above-mentioned existing TOF depth camera scaling scheme, a kind of TOF depth camera three-dimensional coordinate caliberating device based on virtual many cubes standard target and method are provided, this caliberating device comprises three-dimensional motion translation stage, TOF depth camera, cubic objects and background board; This scaling method utilizes three mutually orthogonal motion in one dimension translation stages, makes motion to X, Y, Z tri-orthogonal directionss.By mode of motion reasonable in design, single cubic objects combination in each movement position place TOF depth camera visual field, form virtual many cubes standard target that has complicated shape and multi-characteristic points, obtain the three-dimensional space position of the Corner Feature of this target and surving coordinate and can try to achieve the coordinate conversion relation that three-dimensional coordinate demarcates, realize demarcating the three-dimensional coordinate of TOF depth camera.The present invention greatly reduces single TOF depth camera to the difficulty of Corner feature identification and measuring error, the three-dimensional coordinate of effective raising TOF depth camera is demarcated and measuring accuracy, and the cubical corner location of virtual criterion and feature point number can be arranged flexibly, and be easy to realize full process automatization demarcation.

The technical solution that the present invention adopts is: a kind of TOF depth camera three-dimensional coordinate caliberating device based on virtual many cubes standard target, comprises three-dimensional motion translation stage, TOF depth camera, cubic objects and background board.Wherein, the connected mode of three-dimensional motion translation stage is that three motion in one dimension translation stages are connected in three-dimensional pairwise orthogonal; TOF depth camera is fixed on motion translation platform, carries out three-dimensional motion with three-dimensional motion translation stage; Background board is surface plate, vertical with the optical axis of TOF depth camera, and cubic objects is fixed on background board; The several times utilizing three-dimensional motion translation stage to produce on three-dimensional move, and form virtual many cubes standard target that has complicated shape and multi-characteristic points.

Present invention also offers a kind of TOF depth camera three-dimensional coordinate scaling method based on virtual many cubes standard target, the method comprises the following steps:

(1) TOF depth camera coordinate system OXYZ is first determined, three translation shafts of D translation platform are defined as X, Y, Z tri-directions, true origin O orientates TOF depth camera optical center as, three-dimensional motion translation stage is installed bottom surface and is defined as XZ plane, and to install bottom surface parallel with TOF depth camera; Z-direction is TOF depth camera optical axis direction, parallel with Z-direction translation stage translation shaft direction of motion; Y-direction is the vertical direction that three-dimensional motion translation stage installs bottom surface; X-direction is the direction of right-handed coordinate system definition; Three-dimensional coordinate transformational relation between space coordinates OXYZ and TOF depth camera three-dimensional measurement coordinate system OcXcYcZc is as follows:

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

Wherein, x _c, y _c, z _crepresent the coordinate of any point under TOF depth camera three-dimensional measurement coordinate system on cubic objects, x _w, y _w, z _wrepresent this coordinate under space coordinates OXYZ, nx _x, nx _y, nx _zthe direction vector of representation space coordinate system X-axis under TOF depth camera three-dimensional measurement coordinate system, ny _x, ny _y, ny _zthe direction vector of representation space coordinate system Y-axis under TOF depth camera three-dimensional measurement coordinate system, nz _x, nz _y, nz _zthe direction vector of representation space coordinate system Z axis under TOF depth camera three-dimensional measurement coordinate system, p _x, p _y, p _zthe coordinate of true origin under TOF depth camera three-dimensional measurement coordinate system of representation space coordinate system;

(2) adjust the initial position of TOF depth camera and cubic objects, cubic objects end face and TOF depth camera camera lens surface are close to, and ensure that TOF depth camera camera lens optical axis is by cubic objects center;

(3) controlling Z-direction motion translation platform drives TOF depth camera to move along the Z direction, produces Z-direction precise displacement, and arrive Z-direction and determine sz place, position, Z-direction has been moved;

(4) control X-direction motion translation platform and Y-direction motion translation platform, drive TOF depth camera in sz position, in XY plane, carry out coverage motion, form virtual many cubes standard target; Each position in XY move in plane, four angle point locus coordinates of cubic objects end face uniquely can be determined by the movement position of the length of cubic objects and width and motion translation platform, are shown below:

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

Wherein, i (i=1,2,3 ...) and j (j=1,2,3 ...) be respectively the TOF depth camera position number that X-direction and Y-direction are moved in XY plane; Pij1 (xij1, yij1, zij1), Pij2 (xij2, yij2, zij2), Pij3 (xij3, yij3, zij3), Pij4 (xij4, yij4, zij4) be respectively the locus coordinate of four angle points under space coordinates OXYZ of cubic objects end face; Sxij is the precise displacement that X-direction motion translation platform moves in X-direction; Syij is the precise displacement that Y-direction motion translation platform moves in the Y direction; Sz is the precise displacement that Z-direction motion translation platform moves in Z-direction; L and W is respectively length and the width of cubic objects.

(5) TOF depth camera carries out three-dimensional measurement to cubic objects, obtain the three-dimensional measurement coordinate figure of four corner location of cubic objects end face, that is: the coordinate of four angle points under TOF depth camera three-dimensional measurement coordinate system OcXcYcZc is respectively: Pij1 ' (xij1 ', yij1 ', zij1 '), Pij2 ' (xij2 ', yij2 ', zij2 '), Pij3 ' (xij3 ', yij3 ', zij3 '), Pij4 ' (xij4 ', yij4 ', zij4 ');

(6) travel through whole XY plane, obtain locus and the three-dimensional coordinate measurement value of all XY position cubic objects angle points in this Z-direction position.Bring in above-mentioned three-dimensional coordinate transformational relation, solve linear equations can realize the demarcation of the three-dimensional coordinate to TOF depth camera.

The present invention has following characteristics and good result:

(1) the present invention makes full use of the several times motion on three mutually orthogonal axle high-precision motion translation stages generation three-dimensionals, simple target in each movement position place TOF depth camera visual field combines, form virtual many cubes standard target with complicated shape and unique point, this is one of innovative point being different from existing TOF depth camera three-dimensional coordinate calibration technique;

(2) in the present invention, a target is only had in each movement position place TOF depth camera visual field, and background is simple, make the data handling procedure of each TOF depth camera to target identification and extraction simple, the accurate Corner Feature that can realize simple target extracts and identifies, greatly reduce difficulty and the identification error of target's feature-extraction identification, this is the innovative point two being different from existing TOF depth camera calibration technique;

(3) the present invention is by adopting the three-dimensional motion of mutually orthogonal three-dimensional high-precision motion translation platform, construct the standard target with complicated shape and multi-characteristic points of virtual many cube composition, at the diverse location of TOF depth camera visual field, obtain the three-dimensional space position of three-dimensional measuring result and target, thus the three-dimensional coordinate that can calculate TOF depth camera is demarcated, meet the demand that TOF depth camera three-dimensional coordinate is demarcated, reduce complex target feature identification error, improve the three-dimensional coordinate stated accuracy of TOF depth camera, reduce the systematic error due to the not corresponding introducing of space coordinates and surving coordinate system, and then improve the three-dimensional measurement precision of TOF depth camera, and measuring process and data processing all obviously simplify, be easy to realize whole-course automation demarcate, practical.

Accompanying drawing explanation

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

Fig. 2 is three-dimensional motion translation stage mutually orthogonal in apparatus of the present invention and the structural representation of TOF depth camera thereof;

Fig. 3 is the schematic diagram of target imaging in TOF depth camera visual field when motion translation platform 3 × 3 moves in the present invention;

Fig. 4 is the structural representation of virtual many cubes standard target that in the present invention, motion translation platform 3 × 3 is formed after moving;

Fig. 5 is the locus coordinate schematic diagram of virtual many cubes standard target angle point in XY plane in the present invention.

Embodiment

Below in conjunction with figure and embodiment, the TOF depth camera caliberating device based on virtual many cubes standard target of the present invention and method are described in detail:

As shown in Figure 1, device of the present invention by Z-direction motion translation platform 1, X-direction motion translation platform 2, Y-direction motion translation platform 3, TOF depth camera 4, the formations such as cubic objects 5 and background board 6.Wherein: as shown in Figure 2, X-direction motion translation platform 2, Y-direction motion translation platform 3 and the connected mode of Z-direction motion translation platform 1 are that space three-dimensional direction pairwise orthogonal is connected, the direction of motion of Z-direction motion translation platform 1 is parallel with the optical axis direction of TOF depth camera 4, TOF depth camera 4 is fixed on Y-direction motion translation platform 3, it is parallel that installation bottom surface and the Z-direction motion translation platform of TOF depth camera 4 install bottom surface, and TOF depth camera 4 carries out three-dimensional motion with three motion translation platforms; Background board 6 is surface plate, vertical with the optical axis of TOF depth camera 4, and cubic objects 5 is fixed on background board 6.

The following detailed description of method of the present invention:

(1) TOF depth camera 4 coordinate system OXYZ is first determined, three translation shafts of D translation platform are defined as X, Y, Z tri-directions, true origin O orientates the optical center of TOF depth camera 4 as, three-dimensional motion translation stage is installed bottom surface and is defined as XZ plane, and to install bottom surface parallel with TOF depth camera 4; Z-direction is TOF depth camera 4 optical axis direction, parallel with Z-direction translation stage 1 translation shaft direction of motion; Y-direction is the vertical direction that three-dimensional motion translation stage installs bottom surface; X-direction is the direction of right-handed coordinate system definition; Three-dimensional coordinate transformational relation between space coordinates OXYZ and TOF depth camera 4 three-dimensional measurement coordinate system OcXcYcZc is as follows:

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

Wherein, x _c, y _c, z _crepresent the coordinate of any point under TOF depth camera 4 three-dimensional measurement coordinate system on cubic objects 5, x _w, y _w, z _wrepresent this coordinate under space coordinates OXYZ, nx _x, nx _y, nx _zthe direction vector of representation space coordinate system X-axis under TOF depth camera 4 three-dimensional measurement coordinate system, ny _x, ny _y, ny _zthe direction vector of representation space coordinate system Y-axis under TOF depth camera 4 three-dimensional measurement coordinate system, nz _x, nz _y, nz _zthe direction vector of representation space coordinate system Z axis under TOF depth camera 4 three-dimensional measurement coordinate system, p _x, p _y, p _zthe coordinate of true origin under TOF depth camera 4 three-dimensional measurement coordinate system of representation space coordinate system;

(2) adjust the initial position of TOF depth camera 4 and cubic objects 5, the camera lens surface of the end face of cubic objects 5 and TOF depth camera 4 is close to, and ensure that the camera lens optical axis of TOF depth camera 4 is by cubic objects center;

(3) controlling Z-direction motion translation platform 1 drives TOF depth camera 4 to move along the Z direction, produces Z-direction precise displacement, and arrive Z-direction and determine sz place, position, Z-direction has been moved;

(4) control X-direction motion translation platform 2 and Y-direction motion translation platform 3, drive TOF depth camera 4 in sz position, in XY plane, carry out coverage motion form virtual many cubes standard target; Each position in XY move in plane, four corner location coordinates of cubic objects 5 end face uniquely can be determined by the movement position of the length of cubic objects 5 and width and three motion translation platforms, are shown below:

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

Wherein, i (i=1,2,3 ...) and j (j=1,2,3 ...) be respectively TOF depth camera 4 position number that X-direction and Y-direction are moved in XY plane; Pij1 (xij1, yij1, zij1), Pij2 (xij2, yij2, zij2), Pij3 (xij3, yij3, zij3), Pij4 (xij4, yij4, zij4) is respectively the coordinate of four angle points under space coordinates OXYZ of cubic objects 5 end face; Sxij is the precise displacement that X-direction motion translation platform 2 moves in X-direction; Syij is the precise displacement that Y-direction motion translation platform 3 moves in the Y direction; Sz is the precise displacement that Z-direction motion translation platform 1 moves in Z-direction; L and W is respectively length and the width of cubic objects 5.

(5) TOF depth camera 4 pairs of cubic objects 5 carry out three-dimensional measurement, obtain the three-dimensional measurement coordinate figure of four corner location of cubic objects 5 end face, that is: the coordinate of four angle points under TOF depth camera 4 three-dimensional measurement coordinate system OcXcYcZc is respectively: Pij1 ' (xij1 ', yij1 ', zij1 '), Pij2 ' (xij2 ', yij2 ', zij2 '), Pij3 ' (xij3 ', yij3 ', zij3 '), Pij4 ' (xij4 ', yij4 ', zij4 ');

(6) whole XY plane is traveled through, obtain locus and the three-dimensional measurement coordinate figure of all XY position cubic objects 5 angle points in now Z-direction position, bring in above-mentioned coordinate transformation relation, solve linear equations can realize demarcating the three-dimensional coordinate of TOF depth camera 4, completes whole calibration process.

Visible, by adopting the three-dimensional motion of three mutually orthogonal axle high-precision motion translation stages, construct the standard target with complicated shape and multi-characteristic points of virtual many cube composition, at the diverse location of TOF depth camera 4 visual field, obtain the accurate three-dimensional locus of three-dimensional measuring result and target, thus calculated three-dimensional coordinate demarcation, meet the demand that TOF depth camera 4 three-dimensional coordinate is demarcated, reduce complex target feature identification error, improve the three-dimensional coordinate stated accuracy of TOF depth camera 4, and measuring process and data processing all obviously simplify, be easy to realize whole-course automation demarcate, practical.

Embodiment 1:

(1) with TOF depth camera 4 at 0.5m distance and position place, X-direction motion translation platform 2 and the combination of Y-direction motion translation platform 3 carry out 3 × 3 motions in XY plane for example, describe caliberating device that the present invention introduces in detail and method as follows:

As shown in Figure 1, first TOF depth camera 4 coordinate system OXYZ is determined, three translation shafts of D translation platform are defined as X, Y, Z tri-directions, true origin O orientates the optical center of TOF depth camera 4 as, three-dimensional motion translation stage is installed bottom surface and is defined as XZ plane, and to install bottom surface parallel with TOF depth camera 4; Z-direction is TOF depth camera 4 optical axis direction, parallel with Z-direction translation stage 1 translation shaft direction of motion; Y-direction is the vertical direction that three-dimensional motion translation stage installs bottom surface; X-direction is the direction of right-handed coordinate system definition; Three-dimensional coordinate transformational relation between space coordinates OXYZ and TOF depth camera 4 three-dimensional measurement coordinate system OcXcYcZc is as follows:

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

Wherein, x _c, y _c, z _crepresent the coordinate of any point under TOF depth camera 4 three-dimensional measurement coordinate system on cubic objects 5, x _w, y _w, z _wrepresent this coordinate under space coordinates OXYZ, nx _x, nx _y, nx _zthe direction vector of representation space coordinate system X-axis under TOF depth camera 4 three-dimensional measurement coordinate system, ny _x, ny _y, ny _zthe direction vector of representation space coordinate system Y-axis under TOF depth camera 4 three-dimensional measurement coordinate system, nz _x, nz _y, nz _zthe direction vector of representation space coordinate system Z axis under TOF depth camera 4 three-dimensional measurement coordinate system, p _x, p _y, p _zthe coordinate of true origin under TOF depth camera 4 three-dimensional measurement coordinate system of representation space coordinate system;

(2) adjust the initial position of TOF depth camera 4 and cubic objects 5, the camera lens surface of the end face of cubic objects 5 and TOF depth camera 4 is close to, and ensure that the camera lens optical axis of TOF depth camera 4 is by cubic objects center;

(3) controlling Z-direction motion translation platform 1 drives TOF depth camera 4 to move along the Z direction, produces Z-direction precise displacement, and arrive Z-direction and determine sz=0.5m position, position, Z-direction has been moved;

(4) X-direction motion translation platform 2 and Y-direction motion translation platform 3 is controlled, drive TOF depth camera 4 in sz position, coverage motion is carried out in XY plane, during motion, imaging schematic diagram is as shown in Figure 3 in TOF depth camera 4 visual field for the end face of cubic objects 5, form virtual many cubes standard target schematic diagram as shown in Figure 4, produce X and the displacement of Y-direction accurate benchmark; Each position in XY move in plane, four corner location coordinates of cubic objects 5 end face uniquely can be determined by the movement position of the length of cubic objects 5 and width and three motion translation platforms, the locus coordinate schematic diagram of virtual many cubes standard target angle point in XY plane as shown in Figure 5, is shown below:

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

Wherein, i (i=1,2,3 ...) and j (j=1,2,3 ...) be respectively TOF depth camera 4 position number that X-direction and Y-direction are moved in XY plane; Pij1 (xij1, yij1, zij1), Pij2 (xij2, yij2, zij2), Pij3 (xij3, yij3, zij3), Pij4 (xij4, yij4, zij4) is respectively the coordinate of four angle points under space coordinates OXYZ of cubic objects 5 end face; Sxij is the precise displacement that X-direction motion translation platform 2 moves in X-direction; Syij is the precise displacement that Y-direction motion translation platform 3 moves in the Y direction; Sz is the precise displacement that Z-direction motion translation platform 1 moves in Z-direction; L and W is respectively length and the width of cubic objects 5.

(5) TOF depth camera 4 pairs of cubic objects 5 carry out three-dimensional measurement, obtain the three-dimensional measurement coordinate figure of four corner location of cubic objects 5 end face, that is: the coordinate of four angle points under TOF depth camera 4 three-dimensional measurement coordinate system OcXcYcZc is respectively: Pij1 ' (xij1 ', yij1 ', zij1 '), Pij2 ' (xij2 ', yij2 ', zij2 '), Pij3 ' (xij3 ', yij3 ', zij3 '), Pij4 ' (xij4 ', yij4 ', zij4 ');

(6) whole XY plane is traveled through, obtain the locus amounting to 36 angle points and the three-dimensional measurement coordinate figure of now Z-direction position cubic objects 5, bring in above-mentioned coordinate transformation relation, solve linear equations can realize demarcating the three-dimensional coordinate of TOF depth camera 4, completes whole calibration process.

In the present embodiment, X-direction motion translation platform 2, Y-direction motion translation platform 3 and Z-direction motion translation platform 1 all adopt high precision electric control translation stage, positioning precision is all better than 0.05mm, wherein, X-direction motion translation platform 2 stroke is better than 2m, Y-direction motion translation platform 3 stroke is better than 1m, and Z-direction motion translation platform 1 stroke is better than 0.4m; TOF depth camera 4 three-dimensional measurement distance is 0.5m ~ 5m, and three-dimensional measurement precision is ± 10mm, and cubic objects 5 is the square target of length of side 150mm.Because the positioning precision of electronic control translation stage is far away higher than the measuring accuracy of TOF depth camera 4, therefore the positioning error of motion translation platform self can be ignored.Calibration experiment result shows, whole measuring process achieves whole-course automation, and adopt the measuring accuracy of the calibrated TOF depth camera of scaling method provided by the invention to be brought up to be better than 6.85mm by ± 10mm, achieve the automated high-precision three-dimensional scaling of TOF depth camera.

Embodiment 2:

As shown in Figure 1, cubic objects 5 is the rectangular shape that length, width and height are not exclusively equal, and the miscellaneous part of the present embodiment and principle of work are all identical with embodiment 1.

There is provided above embodiment to be only used to describe object of the present invention, and do not really want to limit the scope of the invention.Scope of the present invention is defined by the following claims.Do not depart from spirit of the present invention and principle and the various equivalent substitutions and modifications made, all should contain within the scope of the present invention.

Claims (6)

1. the TOF depth camera three-dimensional coordinate caliberating device based on virtual many cubes standard target, comprise three-dimensional motion translation stage, TOF depth camera, cubic objects and background board, it is characterized in that: the connected mode of described three-dimensional motion translation stage is that three motion in one dimension translation stages are connected in three-dimensional pairwise orthogonal, TOF depth camera is fixed on three-dimensional motion translation stage, three-dimensional motion is carried out with three-dimensional motion translation stage, background board is surface plate, vertical with the optical axis of TOF depth camera, cubic objects is fixed on background board; The several times utilizing three-dimensional motion translation stage to produce on three-dimensional move, and form virtual many cubes standard target that has complicated shape and multi-characteristic points.

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

3. device according to claim 1, is characterized in that: described three-dimensional motion translation stage adopts electronic control translation stage to realize three-dimensional motion.

4. device according to claim 1, is characterized in that: described cubic objects is the square target that the length of side is equal.

5. device according to claim 1, is characterized in that: described cubic objects is the rectangular parallelepiped target that length, width and height are not exclusively equal.

6., based on a TOF depth camera three-dimensional coordinate scaling method for virtual many cubes standard target, it is characterized in that described scaling method comprises the following steps:

(1) TOF depth camera coordinate system OXYZ is first determined, three translation shafts of D translation platform are defined as X, Y, Z tri-directions, true origin O orientates TOF depth camera optical center as, three-dimensional motion translation stage is installed bottom surface and is defined as XZ plane, and to install bottom surface parallel with TOF depth camera; Z-direction is TOF depth camera optical axis direction, parallel with Z-direction translation stage translation shaft direction of motion; Y-direction is the vertical direction that three-dimensional motion translation stage installs bottom surface; X-direction is the direction of right-handed coordinate system definition; Three-dimensional coordinate transformational relation between space coordinates OXYZ and TOF depth camera three-dimensional measurement coordinate system OcXcYcZc is as follows:

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

Wherein, x _c, y _c, z _crepresent the coordinate of any point under TOF depth camera three-dimensional measurement coordinate system on cubic objects, x _w, y _w, z _wrepresent this coordinate under space coordinates OXYZ, nx _x, nx _y, nx _zthe direction vector of representation space coordinate system X-axis under TOF depth camera three-dimensional measurement coordinate system, ny _x, ny _y, ny _zthe direction vector of representation space coordinate system Y-axis under TOF depth camera three-dimensional measurement coordinate system, nz _x, nz _y, nz _zthe direction vector of representation space coordinate system Z axis under TOF depth camera three-dimensional measurement coordinate system, p _x, p _y, p _zthe coordinate of true origin under TOF depth camera three-dimensional measurement coordinate system of representation space coordinate system;

(2) adjust the initial position of TOF depth camera and cubic objects, cubic objects end face and TOF depth camera camera lens surface are close to, and ensure that TOF depth camera camera lens optical axis is by cubic objects center;

(3) controlling Z-direction motion translation platform drives TOF depth camera to move along the Z direction, produces Z-direction precise displacement, and arrive Z-direction and determine sz place, position, Z-direction has been moved;

(4) control X-direction motion translation platform and Y-direction motion translation platform, drive TOF depth camera in sz position, in XY plane, carry out coverage motion, form virtual many cubes standard target; Each position in XY move in plane, four feature angle point position coordinateses of cubic objects end face uniquely can be determined by the movement position of the length of cubic objects and width and motion translation platform, are shown below:

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

Wherein, i and j is respectively the position number of TOF depth camera X-direction and Y-direction motion in XY plane, i=1, and 2,3 ..., j=1,2,3, Pij1 (xij1, yij1, zij1), Pij2 (xij2, yij2, zij2), Pij3 (xij3, yij3, zij3), Pij4 (xij4, yij4, zij4) is respectively the coordinate of four angle points under space coordinates OXYZ of cubic objects end face; Sxij is the precise displacement that X-direction motion translation platform moves in X-direction; Syij is the precise displacement that Y-direction motion translation platform moves in the Y direction; Sz is the precise displacement that Z-direction motion translation platform moves in Z-direction; L and W is respectively length and the width of cubic objects;

(5) TOF depth camera carries out three-dimensional measurement to cubic objects, obtain the three-dimensional measurement coordinate figure of four corner location of cubic objects end face, that is: the coordinate of four angle points under TOF depth camera three-dimensional measurement coordinate system OcXcYcZc is respectively: Pij1 ' (xij1 ', yij1 ', zij1 '), Pij2 ' (xij2 ', yij2 ', zij2 '), Pij3 ' (xij3 ', yij3 ', zij3 '), Pij4 ' (xij4 ', yij4 ', zij4 ');

(6) travel through whole XY plane, obtain locus and the three-dimensional coordinate measurement value of all XY position cubic objects angle points in this Z-direction position.Bring in above-mentioned three-dimensional coordinate transformational relation, namely solve linear equations realizes the demarcation of the three-dimensional coordinate to TOF depth camera.