基于指数积公式的串联机器人运动学参数标定方法

One of the efficient methods to upgrade the robot's positioning accuracy is to calibrate the kinematic parameters. A method based on the Product-of-Exponential (POE) formula to calibrate the kinematic parameters is proposed, which only requires measuring the position coordinates of end effector. The forward kinematics model is established for the serial robot, and the general formulation of its positioning error is derivated. By the adjoint transformation, an equal model of robot's kinematic error is set up after the errors of reference configuration and rigid displacement between the base coordinating system and the measuring coordinating system are equivalently transferred to the zero errors of the robot's joints. Using the geometrical constrains between the twist coordinates, it is pointed out that the number of maximum parameter of every joint to be calibrated is 5, and a practically calibratable kinematic error model is forwarded only requiring measuring the position coordinates. A calibration method to kinematic parameters is designed based on the POE formula, which is used in the industrial robot calibration experiments. It is proved that the calibration method can improve the level of absolute positioning error of the target robot.