基于位置约束的工业机器人运动学标定∗

摘要

Given the standard DH method was limited to describe parallel joint, MDH method was adopted to establish the robot kinematics. Based on the end position constraint, a general method was proposed to es-tablish the linear equations for structure parameter identification. To solve the degradation problems in the coefficient matrix of the equations, starting from the Jacobian matrix of the kinematics, the reasons for the degradation was analyzed. It was the theoretical basis to select the structural parameters. The conversion be-tween robot base coordinate system and the measurement coordinate system was discussed and then a simple calibration method based on the cross-bar was designed without coordinate conversion. After the simulation conducted in matlab, MOTOMAN-MH6 robot was calibrated by this method. After calibration, the cross bar length error calculated under teaching readings reduced from 4mm to less than 1mm. The results show that the calibration method is effective.%鉴于标准DH方法在描述平行关节时存在问题，采用MDH方法建立机器人的运动学，提出基于末端位置约束关系建立线性方程组进行结构参数辨识的一般方法。针对方程组系数矩阵退化的问题，从运动学的雅可比矩阵入手，分析了退化的原因，为结构参数选择提供了理论依据。讨论了机器人基坐标系和测量坐标系转换的问题，设计了一种无需坐标系转换的基于十字型杆件的简易标定方法。基于matlab进行仿真后，采用该方法标定MOTOMAN-MH6机器人，标定后，按照示教器读数计算的十字型杆件长度误差从4 mm降低到1 mm以内，说明该方法是有效的。