Visual alignment technology based on laser rangefinder

LIU Xing1, ZHANG Ai-jun1, CAO Xiao-bing2
(1.School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210000,China; 2.School of Control Technology, Wuxi Institute of Technology, Wuxi 214121China)

Abstract: Aiming at the posture correction of the vision system at the end of the manipulator, a technique of vision alignment with laser rangefinder was proposed. Firstly, the camera imaging model and the hand-eye relation model were established. Then the position calibration model of the laser rangefinder at the end of the manipulator was established and the nonlinear optimization algorithm based on plane constraint was used to solve the laser source coordinates and the unit direction vector of the laser line in the coordinate system of the end flange of the manipulator. Finally, a vision alignment model was established. The plane equation was fitted to the laser points projected on the target plane and the plane unit normal vector was obtained. Combined with the handeye relationship and the alignment relationship, an optimization algorithm was used to solve the posture correction angle of the robot, and the posture angle was sent to the robot to adjust the end pose to finally align the camera plane with the target plane. The results indicate that the camera attitude correction error within 10° is within 0.6°, and it has higher precision and better stability compared with the posture correction method based on PNP principle.
Key words: monocular vision; industrial robots; calibration of laser rangefinder; posture correction