CN102980542B - Multiple-sensor united calibration method - Google Patents
Multiple-sensor united calibration method Download PDFInfo
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- CN102980542B CN102980542B CN201210429184.4A CN201210429184A CN102980542B CN 102980542 B CN102980542 B CN 102980542B CN 201210429184 A CN201210429184 A CN 201210429184A CN 102980542 B CN102980542 B CN 102980542B
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Abstract
The invention discloses a multiple-sensor united calibration method and relates to sensor calibration. The multiple-sensor united calibration method comprises the following steps: calibrating camera parameters through a circular hole target component; calibrating a contact-type measuring head through a standard ball; and united calibration of a camera and the contact-type measuring head. Measurement on geometric dimensioning and form and position errors of small structures can be achieved through data processing in the multiple-sensor united calibration method, ranges in practical application are enlarged, and demands in practical application are met.
Description
Technical field
The present invention relates to transducer calibration, particularly a kind of multisensor combined calibrating method.
Background technology
In multisensor syste, multisensor registration technique is a wherein key technology.So-called registration refers to and is transformed in the process of a public system by the information from different sensors, make the minimize systematic errors because the reasons such as space-time calibration, ordinate transform, the skew of sensor own location information and detection skew cause, control the stability of sensing system, thus ensure that follow-up multi-sensor data fusion can correctly, effectively realize.For obtaining the transformational relation of relative position between each sensor coordinate system and direction, need the combined calibrating carrying out multisensor.
Usually adopt plane reference plate to demarcate separately camera in prior art, to be published picture the position of circular hole in picture and actual difference by the graphical analysis of acquisition plane scaling board, calibrate the distortion parameter etc. of camera.
Inventor is realizing in process of the present invention, finds at least there is following shortcoming and defect in prior art:
Machine components are often designed with the micro-structure that groove, chamfering or central angle are less than the precisions such as the short circular arc of 20 degree, provide for sealing lubricating fluid up for safekeeping the installation cooperation that special passage also facilitates part.The end face of these micro-structures is often region feature, due to reasons such as end face is reflective, end slopes, the contour images that existing multisensor calibration technique collects can not accurately reflect end face position, namely cannot measure the marginal position of these structures exactly.
Summary of the invention
The invention provides a kind of multisensor combined calibrating method, achieve the measurement to micro-structure and location, expand the scope in practical application, meet the needs in practical application, described below:
A kind of multisensor combined calibrating method, said method comprising the steps of:
Circular hole targets tender is utilized to demarcate camera parameter; Standard ball is utilized to demarcate contact measuring head; The combined calibrating of camera and contact measuring head;
Wherein, the combined calibrating of described camera and contact measuring head is specially:
1) initial position got back to by camera, and imaging is in the camera held in the survey of contact measuring head, obtains image;
2) by the matching center of circle O (Y of image
i, Z
i) as the characteristic point participating in demarcating, camera initial position is demarcated, obtain camera initial position calibration result;
Measuring machine coordinate is (X
m, Y
m, Z
m), the linear relationship between camera and measuring machine is specially:
X
M=X
I+a
0；Y
M=b
0+a
1Y
I+a
2Z
I；Z
M=c
0+b
1Y
I+b
2Z
I；
Wherein a
0, b
0and c
0represent the translational movement being tied to measuring machine coordinate system from image coordinate respectively; a
1, b
1, a
2and b
2represent that image coordinate is tied to the parameter in the spin matrix of measuring machine coordinate system; Y
ito and Z
iparallel with circular hole targets tender place plane to the plane formed, and the distance between two planes is object space focal length, Y
ito and Z
ito mutually vertical, X
ito perpendicular to Y
ito and Z
ito the plane formed;
3) amount of exercise (Δ M, △ Y, △ Z) moved with motion according to camera initial position calibration result and camera obtains final calibration result;
Describedly utilize circular hole targets tender to carry out demarcation to camera parameter to be specially:
1) circular hole targets tender maintains static, and camera to be fixed on motion and along Y
ito and Z
ito the translational motion making two dimension, using the center of circle of circular hole targets tender as characteristic point, record motion coordinate value and characteristic point plane of delineation coordinate value on each position respectively;
2) corresponding relation between motion coordinate value and characteristic point plane of delineation coordinate value is utilized to demarcate camera.
Describedly record motion coordinate value and characteristic point plane of delineation coordinate value on each position respectively and be specially:
Obtain motion coordinate value by grating scale or laser interferometer, sub-pix segmentation is done to the image of circular hole targets tender, adopt the method in the least square fitting center of circle to obtain characteristic point plane of delineation coordinate value.
The beneficial effect of technical scheme provided by the invention is: this method, by effectively the measurement data under each sensor and different coordinates being transformed in unified measuring machine coordinate system the demarcation of camera and contact measuring head, solves the registration problems of multisensor.The method accurately defines the corresponding relation of contact measuring head and camera image coordinate value, when measuring the micro-structure containing region feature, utilize the coordinate information of collected by camera non-face structure division, contact measuring head is used to gather face structure division coordinate information, and by the information unification that collects in a coordinate system, complete the measurement to micro-structure physical dimension and Form and position error through data processing; Achieve the measurement to micro-structure and location, expand the scope in practical application, meet the needs in practical application.
Accompanying drawing explanation
Fig. 1 is certain type multisensor set measuring machine schematic diagram;
Fig. 2 is circular hole targets tender schematic diagram;
Fig. 3 is the schematic diagram of actual image point and ideal image point coordinate;
Fig. 4 is the schematic diagram of U to distortion;
Fig. 5 is the schematic diagram of V to distortion;
Fig. 6 is standard ball and the calibration strategy schematic diagram of demarcating touch trigger probe;
Fig. 7 is the image surveying end and the matching center of circle thereof;
Fig. 8 surveys the schematic diagram of the end centre of sphere at image coordinate system;
Fig. 9 is a kind of flow chart of multisensor combined calibrating method.
Shown in accompanying drawing, components listed is listed as follows:
1: main shaft; 2: contact is popped one's head in;
3: marble workbench; 4: camera;
5: vertical linear module; 6: horizontal linear module;
7: standard ball.
Detailed description of the invention
For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.
In order to realize measurement to micro-structure and location, expand the scope in practical application, meet the needs in practical application, the embodiment of the present invention proposes a kind of multisensor combined calibrating method, described below:
101: utilize circular hole targets tender to demarcate camera parameter;
1) circular hole targets tender maintains static, and camera to be fixed on motion and along Y
ito and Z
ito the translational motion making two dimension, using the center of circle of circular hole targets tender as characteristic point, record motion coordinate value and characteristic point plane of delineation coordinate value on each position respectively;
See Fig. 1 and Fig. 2, the diverse location imaging of circular hole targets tender in CCD image planes, mobile camera moves according to above-mentioned direction, obtains motion coordinate value and characteristic point plane of delineation coordinate value on each position.Y
ito and Z
iparallel with circular hole targets tender place plane to the plane formed, and the distance between two planes is object space focal length, Y
ito and Z
ito mutually vertical, X
ito perpendicular to Y
ito and Z
ito the plane formed.Motion is generally: guide rail or linear module etc. can drive the device of camera movement, and the embodiment of the present invention does not limit at this.
Wherein, record motion coordinate value and characteristic point plane of delineation coordinate value on each position to be respectively specially: obtain motion coordinate value by grating scale or laser interferometer, sub-pix segmentation is done to the image of circular hole targets tender, adopt the method in the least square fitting center of circle to obtain characteristic point plane of delineation coordinate value.
2) corresponding relation between motion coordinate value and characteristic point plane of delineation coordinate value is utilized to demarcate camera.
Consider that near image plane center, distortion is less, first utilize 4 × 4 characteristic points in image plane center region (during specific implementation, determine the quantity of characteristic point according to needing in practical application) data ask for the internal and external parameter of camera ideal model, then solve the distortion error of each point.
The ideal image point coordinate calculated by camera projection ideal model parameter and actual image point coordinate are as shown in Figure 3.In the image planes calculated each point U to V to distortion error, respectively as shown in Figure 4 and Figure 5, table 1 is calibration result.
(α, beta, gamma) is tied to three Eulerian angles of the spin matrix of image coordinate system for camera coordinates; T=[t
x, t
y, t
z]
tfor camera coordinates is tied to the translation vector of image coordinate system; f
uand f
vbe respectively the effective focal length of plane of delineation coordinate system horizontal stroke, y direction, unit is pixel; K is horizontal, that longitudinal axis axle is inclined modifying factor; (u
0, v
0) be the intersection point of camera lens primary optical axis and the plane of delineation;
for the distortion factor vector simplified.Utilize the instrument coordinates value of camera model reverse picture point, and make comparisons with the coordinate value that measuring machine grating scale reads, deviation is therebetween called object point error.Experiment shows: the object point error of 49 picture points utilizing camera projection ideal model to try to achieve is respectively 0.006491mm and 0.009831mm in the standard deviation of Y-direction and Z-direction; The standard deviation being obtained Y-direction and Z-direction by above-mentioned demarcation is respectively 0.002761mm and 0.004012mm, and the intrinsic parameter indicating camera obtains demarcation, improves the degree of accuracy of camera.
102: utilize standard ball to demarcate contact measuring head;
The object that contact measuring head is demarcated is the sphere center position correctly determining to survey end, and the equivalent diameter obtaining survey end compensates to obtain precise measurement results to call it when actual measurement to measurement point.Sphere centre coordinate (the X of standard ball
c, Y
c, Z
c), the embodiment of the present invention is that the ceramic material standard ball of 25.3986mm is described for example with diameter, and survey end radius to be calibrated is R
c.The calibration method that the B89 standard formulated according to American National Standards Institute (ANSI) measures the probe location error of 49 points in standard ball is demarcated.49 points comprise each 12 points in standard ball on 4 specific latitude (being roughly 100 °, 90 °, 60 ° and 30 °) cross sections and 1 arctic point, as shown in Figure 6.Require during detection that the point in each cross section offsets one from another, to ensure that gauge head detects from different directions, usually make the some rotation 10 ° of adjacent sections.Through detecting, obtain contact measuring head end radius R
cside-play amount (the D of=3.9982mm contact measuring head pedestal relative to it
x, D
y, D
z), obtain each offset component D
x=0.2135mm, D
y=-0.1823mm, D
z=-21.8695mm.And contact measuring head pedestal has fixing side-play amount relative to grating scale, namely in the movable scope of contact measuring head, the position of contact measuring head end in measuring machine coordinate system can accurately obtain.
103: the combined calibrating of camera and contact measuring head;
1) initial position got back to by camera, and imaging is in the camera held in the survey of contact measuring head, obtains image;
Control the motion back to zero of camera position, camera is made to be positioned at initial position, now control survey machine is surveyed to hold and is moved, diameter D=4.0mm is made to survey end (when adopting the contact measuring head of other models, surveying end, diameter is corresponding changes, the embodiment of the present invention does not limit this) just can clearly imaging in the camera, as shown in Figure 7.
2) by the matching center of circle O (Y of image
i, Z
i) as the characteristic point participating in demarcating, camera initial position is demarcated, obtain camera initial position calibration result;
Measuring machine coordinate is (X
m, Y
m, Z
m), the linear relationship between camera and measuring machine is specially:
X
M=X
I+a
0(1)
Y
M=b
0+a
1Y
I+a
2Z
I(2)
Z
M=c
0+b
1Y
I+b
2Z
I(3)
Wherein a
0, b
0and c
0represent the translational movement being tied to measuring machine coordinate system from image coordinate respectively; a
1, b
1, a
2and b
2represent that image coordinate is tied to the parameter in the spin matrix of measuring machine coordinate system.
For enabling the survey end of contact measuring head become blur-free imaging in the picture, the survey end keeping in touch formula gauge head does not move in X-direction, and control survey machine is surveyed end and moved in Y, Z-direction, and the survey end of contact measuring head is in the diverse location imaging of CCD image planes.As shown in Figure 8, each matching center of circle in the array distribution of 11 × 8, utilizes this 88 groups of coordinate data composition over-determined systems, uses least square method to solve seven coefficients, thus realize demarcating, obtain camera initial position calibration result in image planes.
3) amount of exercise (Δ X, Δ Y, △ Z) moved with motion according to camera initial position calibration result and camera obtains final calibration result, and (Δ X, Δ Y, △ Z) represents the side-play amount of motion relative initial position.
Owing to just demarcating at camera initial position, after camera is with motion motion (Δ X, Δ Y, △ Z), the survey end of the contact measuring head of energy blur-free imaging should be under measuring machine coordinate system:
By above step, the combined calibrating of camera and contact measuring head completes, and a bit can obtain this coordinate position in measuring machine by certain acquisition in image.
The combined calibrating of camera and contact measuring head is realized below for the measuring machine in Fig. 1, described below:
This measuring machine specifically comprises: marble workbench 3, main shaft 1, X-axis and Y-axis, and main shaft 1 is as Z axis; Marble workbench 3 is provided with standard ball 7 and the vertical linear module 5 along Y-axis movement; The bottom of main shaft 1 is provided with contact measuring head 2; Vertical linear module 5 is fixedly installed horizontal linear module 6; Horizontal linear module 6 moves up and down on vertical linear module 5; Horizontal linear module 6, vertical linear module 5, main shaft 1, X-axis and Y-axis are respectively arranged with grating scale; Horizontal linear module 6 is provided with camera 3; Horizontal linear module 6 and vertical linear module 5 are equivalent to motion above; Camera 3 is along Y
ito and Z
ito the translational motion making two dimension.Adopt above-described method to carry out combined calibrating, obtain the calibration result in table 1 and table 2.
Table 1 camera internal and external parameter calibration result
Table 2 combined calibrating coefficient repeated experiment result
By the demarcation of the internal and external parameter to camera 6, the distortion of camera 6 is corrected, improve the degree of accuracy of camera 6; By the calibration coefficient that obtains in table 2 repeatability worst error value at below 0.01mm, meet the requirement of combined calibrating well, the method for this combined calibrating can be adopted to realize carrying out accurate measurement to micro-structure.Detailed process is for measure micro-structure region feature by contact measuring head 3, the remaining edge information of this small mechanism is measured by camera, the data point coordinate gathered by camera 6 is afterwards transformed in measuring machine coordinate system by the relation that combined calibrating obtains, and unites to measure this micro-structure with the region feature data message gathered before.Effectively can solve traditional multisensor by said method to be difficult to measure the problem of micro-structure.
It will be appreciated by those skilled in the art that accompanying drawing is the schematic diagram of a preferred embodiment, the invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1. a multisensor combined calibrating method, is characterized in that, said method comprising the steps of:
Measuring machine comprises: workbench and main shaft;
Be provided with standard ball and the vertical linear module along Y-axis movement on the table; The bottom of main shaft is provided with contact measuring head; Vertical linear module is fixedly installed horizontal linear module; Horizontal linear module moves up and down on vertical linear module; Horizontal linear module is provided with camera; Horizontal linear module and vertical linear module are equivalent to motion;
Circular hole targets tender is utilized to demarcate camera parameter; Standard ball is utilized to demarcate contact measuring head;
The combined calibrating of camera and contact measuring head; Wherein, the combined calibrating of described camera and contact measuring head is specially:
1) initial position got back to by camera, and imaging is in the camera held in the survey of contact measuring head, obtains image;
2) for enabling the survey end of contact measuring head become blur-free imaging in the picture, the survey end keeping in touch formula gauge head does not move in X-direction, and control survey machine is surveyed end and moved in Y, Z-direction, by the matching center of circle O (Y of image
i, Z
i) as the characteristic point participating in demarcating, camera initial position is demarcated, obtain camera initial position calibration result;
Measuring machine coordinate is (X
m, Y
m, Z
m), the linear relationship between camera and measuring machine is specially:
X
M＝X
I+a
0；Y
M＝b
0+a
1Y
I+a
2Z
I；Z
M＝c
0+b
1Y
I+b
2Z
I；
Wherein a
0, b
0and c
0represent the translational movement being tied to measuring machine coordinate system from image coordinate respectively; a
1, b
1, a
2and b
2represent that image coordinate is tied to the parameter in the spin matrix of measuring machine coordinate system; Y
ito and Z
iparallel with circular hole targets tender place plane to the plane formed, and the distance between two planes is object space focal length, Y
ito and Z
ito mutually vertical, X
ito perpendicular to Y
ito and Z
ito the plane formed;
3) amount of exercise (Δ X, Δ Y, Δ Z) moved with motion according to camera initial position calibration result and camera obtains final calibration result;
2. a kind of multisensor combined calibrating method according to claim 1, is characterized in that, describedly utilizes circular hole targets tender to carry out demarcation to camera parameter to be specially:
1) circular hole targets tender maintains static, and camera to be fixed on motion and along Y
ito and Z
ito the translational motion making two dimension, using the center of circle of circular hole targets tender as characteristic point, record motion coordinate value and characteristic point plane of delineation coordinate value on each position respectively;
2) corresponding relation between motion coordinate value and characteristic point plane of delineation coordinate value is utilized to demarcate camera.
3. a kind of multisensor combined calibrating method according to claim 2, is characterized in that, describedly records motion coordinate value and characteristic point plane of delineation coordinate value on each position respectively and is specially:
Obtain motion coordinate value by grating scale or laser interferometer, sub-pix segmentation is done to the image of circular hole targets tender, adopt the method in the least square fitting center of circle to obtain characteristic point plane of delineation coordinate value.
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| CN106052607B (en) * | 2016-06-28 | 2019-03-12 | 天津大学 | The standard and application method of multisensor measuring machine coordinate unification and precision verification |
| CN106092008B (en) * | 2016-06-28 | 2019-03-12 | 天津大学 | The coordinate unification calibration device and scaling method of high-accuracy composite type measuring machine |
| CN106705888B (en) * | 2016-12-05 | 2019-04-09 | 北京空间机电研究所 | CCD coordinate system and mirror surface coordinate system non-linear relation scaling method in interference detection |
| CN106871949B (en) * | 2017-04-17 | 2019-03-15 | 重庆市计量质量检测研究院 | More ball plate standards and joint error detection method for multi-sensor measurement system |
| CN107063330B (en) * | 2017-04-17 | 2019-03-15 | 重庆市计量质量检测研究院 | Porous plate standard and joint error detection method for multi-sensor measurement system |
| CN107991665A (en) * | 2017-11-23 | 2018-05-04 | 江苏理工学院 | It is a kind of based on fixed-focus camera to target three-dimensional coordinate method for continuous measuring |
| CN108286946B (en) * | 2018-01-30 | 2020-03-31 | 周蕊 | Method and system for sensor position calibration and data splicing |
| CN108444419A (en) * | 2018-02-01 | 2018-08-24 | 阿尔特汽车技术股份有限公司 | Realize three coordinate arrangement on-line measurement systems and method |
| CN110220454B (en) * | 2019-06-03 | 2020-11-13 | 西安飞机工业（集团）有限责任公司 | Pose calibration method of three-coordinate positioning mechanism |
| CN110458894B (en) * | 2019-07-31 | 2023-05-09 | 天津大学 | Calibration method for camera and contact type measuring head of measuring machine |
| CN110567372A (en) * | 2019-09-16 | 2019-12-13 | 立讯智造(浙江)有限公司 | Auxiliary measuring tool |
| CN111182290B (en) * | 2019-12-31 | 2021-11-19 | 未来（北京）黑科技有限公司 | Image detection method and device, storage medium and electronic device |
| CN111833396B (en) * | 2020-06-05 | 2024-03-29 | 哈工大机器人(中山)无人装备与人工智能研究院 | Method and system for converting camera coordinate system of blood sampling device into world coordinate system |
| CN112729087B (en) * | 2020-12-16 | 2022-03-22 | 中国科学院苏州生物医学工程技术研究所 | Differential eddy current micro-displacement sensor calibration device, method, computer equipment and storage medium |
| CN112665517B (en) * | 2020-12-17 | 2022-06-14 | 太原科技大学 | Multi-camera large-view-field surface shape measurement calibration method |
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