并联式曲线送料平台机构误差补偿方法的研究

并联式曲线送料平台是用于实现细木工带锯机曲线切割的自动进给平台,由于该机构运动支链多,机构误差大,难以实现平台末端位姿的精确进给。为了实现并联式曲线送料平台的末端位姿误差补偿,本文从连杆运动学位姿建模出发,利用机构运动学逆解的分析方法,得到各关节参数与送料平台位姿参数关系方程,再运用尺寸矢量链法建立机构误差、机构参数与动平台位姿误差的误差正解数学模型,分离得到与动平台位姿参数有关的误差传递矩阵,最终得到由各轴驱动来补偿平台机构误差的方法。运用该方法对并联式曲线送料平台误差实例进行计算分析,结合MATLAB计算得到送料平台各轴随加工曲线变化的误差补偿实际值,数值导入到各轴进给补偿程序中对曲线送料平台试验机进行实验验证。结果表明:并联式曲线送料平台机构误差补偿方法有效地减小了末端执行机构的位姿误差。未补偿前并联式曲线送料平台工件运动曲线X轴、Y轴方向最大误差为3 mm,绕Z轴最大旋转误差为3°;补偿后工件运动曲线X轴、Y轴方向最大误差在1 mm以内,绕Z轴最大旋转误差在1°以内。说明本方法能够显著提高并联式曲线送料平台的精度,有效地补偿并联式曲线送料平台的机构误差。 

Mechanism error compensation method of parallel curve feeding platform

Parallel curve feeding platform is an automatic feeding platform which is used to realize the fine woodworking band saw curvilinear cutting. Due to the large number of branches, the mechanism error is large;therefore, it is difficult to realize the precise feeding of the end position of the platform. This article starts from modeling the connecting rod motion degree appearance, using the mechanism of inverse kinematics analysis method, to get parameters of each joint and relationship equation of feeding platform position parameters. Then, we establish the mathematical model of the positive solutions of a system error and parameters and the posture error of moving platform using the vector size chain method, extract error transfer matrix associated with moving platform pose parameters, and at last get the method driven by the shaft to error compensation platform agencies. Using this method, we calculate and analyze the error of parallel curve feeding platform, and combine with MATLAB to calculate the actual error compensation values of feeding platform axes changing with processing curve. The values are put into each axis ’ feeding compensation program for experimental validation on curve feed platform testing machine. The results show that this mechanism error compensation method of parallel curve feeding platform effectively reduces the end of the actuator position error. Before the compensation, the maximum error of the X axis and Y axis direction of the motion curve of the work-piece on the parallel curve feeding platform is 3 mm, and around the Z axis rotation error is 3 degrees. After the compensation, the maximum error of the X axis and Y axis direction of the motion curve of the work-piece is within 1 mm, and around the Z axis rotation error is within 1 degree. This method can significantly improve the precision of the feeding platform, and effectively compensate feeding platform error.