US 11,992,959 B1
Kinematics-free hand-eye calibration method and system
Jian Gao, Guangzhou (CN); Guoqing Wu, Guangzhou (CN); Zhuojun Zheng, Guangzhou (CN); Lanyu Zhang, Guangzhou (CN); Yuheng Luo, Guangzhou (CN); Disai Chen, Guangzhou (CN); and Xin Chen, Guangzhou (CN)
Assigned to GUANGDONG UNIVERSITY OF TECHNOLOGY, Guangzhou (CN)
Filed by GUANGDONG UNIVERSITY OF TECHNOLOGY, Guangzhou (CN)
Filed on Jan. 2, 2024, as Appl. No. 18/402,139.
Application 18/402,139 is a continuation of application No. PCT/CN2023/122591, filed on Sep. 28, 2023.
Claims priority of application No. 202310345999.2 (CN), filed on Apr. 3, 2023.
Int. Cl. B25J 9/16 (2006.01); G06T 7/70 (2017.01)
CPC B25J 9/1692 (2013.01) [G06T 7/70 (2017.01); G06T 2207/30244 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A kinematics-free hand-eye calibration method, comprising the following steps of:
S1: building a hand-eye calibration platform with eyes outside a hand based on a five-axis motion platform;
S2: controlling one of translation axes of the five-axis motion platform to perform a single-axis point location motion, wherein the translation axes of the controlled five-axis motion platform comprising an X-axis, a Y-axis and a Z-axis;
S3: collecting a first spatial coordinate of a calibration plate in a process of controlling the five-axis motion platform to perform the single-axis point location motion by a camera;
S4: after the collected first spatial coordinate reaching a first preset number, fitting all the first spatial coordinates into a spatial straight line;
S5: judging whether distances of all the first spatial coordinates deviating from the spatial straight line being within a first maximum deviation distance range, if so, obtaining a unit direction vector of the spatial straight line according to a spatial straight line equation, if not, eliminating the first spatial coordinate with the largest deviation distance and returning to step S4;
S6: judging whether the single-axis point location motion of all translation axes of the five-axis motion platform having been completed, if not, controlling the five-axis motion platform to perform the single-axis point location motion on the next translation axis and returning to step S3; if so, executing step S7;
S7: carrying out Schmidt orthogonalization on the unit direction vectors of the spatial straight lines of the X-axis, the Y-axis and the Z-axis to obtain a pose relationship matrix combined by the orthogonalized direction vectors;
S8: controlling the five-axis motion platform to reset;
S9: deflecting an A-axis of the five-axis motion platform at a preset angle, deflecting a C-axis of the five-axis motion platform for a plurality of times, and recording a second spatial coordinate of the corresponding calibration plate when deflecting the C-axis each time;
S10: after the collected second spatial coordinates reaching a second preset number, fitting all the second spatial coordinates into a spatial spherical surface;
S11: judging whether distances of all the second spatial coordinates deviating from the spatial spherical surface being within a second maximum deviation distance range, if so, calculating a spherical center coordinate of the spatial spherical surface to obtain a position relationship matrix, if not, eliminating the second spatial coordinate with the largest deviation distance and returning to step S10; and
S12: obtaining a hand-eye relationship matrix according to the pose relationship matrix and the position relationship matrix.