机械臂D-H参数和减速比几何标定及误差补偿

Geometrical Calibration and Error Compensation of D-H Parameters and Joint Reduction Ratios of Manipulator

摘要:

针对机械臂D-H参数和关节电机减速比不精确导致机械臂绝对定位精度降低的问题,提出了在利用几何分析标定机械臂D-H参数的基础上,通过分析关节实际旋转角度和相应电机编码器码值的线性关系,标定关节电机减速比的方法;针对关节角误差微分补偿法计算量大的缺点,通过推导机械臂末端位姿矩阵误差和关节角误差之间的微分关系建立误差模型,求解关节补偿角,避免了雅各比矩阵的求取,提高了计算效率;最后采用三维激光跟踪仪搭建测量系统,完成了一种6自由度机械臂的标定及补偿实验;实验结果表明,通过参数标定及误差补偿,机械臂的绝对定位误差均值从标定前的2.83 mm和1.14°降低到0.54 mm和0.24°,验证了方法的有效性。

Abstract:

To solve the problem that the inaccuracy of D-H model parameters and joint motor reduction ratios would reduce the absolute positioning accuracy of manipulator, proposed a solution based on the calibration of D-H model parameters with geometric analysis, and through analyzing the relationship between the actual joint rotation angle and the output value of the joint motor encoder, to calibrate the Joint motor reduction ratios. Counter the disadvantages of traditional joint angle error differential compensation method,by analyzing the differential relationship between pose matrix error of the end of manipulator and joint angle error to get joint compensation angle, the jacoby matrix calculation is avoided, and the calculation efficiency is improved. Finally, built a measurement system with 3D laser tracker, and accomplished the calibration and compensation experiment of a manipulator with 6 degrees of freedom. Result of the experiment shows that through parameter calibration and compensation, the average value of the absolute positioning error of the manipulator are reduced to 0.54 mm and 0.24° from the original 2.83 mm and 1.14°, which verifies the validity of the method.