3-RPS并联机构运动学标定方法的研究

针对六轴混联机床中因3-RPS并联机构结构参数误差引起的精度问题,分析了影响3-RPS并联机构几何精度的误差因素,给出了并联机构的误差模型；基于影响并联机构定平台运动精度较大的几何误差参数；建立了运动学标定模型.采用阻尼最小二乘法,经多次优化迭代实现了利用一组测量数据完成非线性超越矛盾标定方程组的求解.利用激光干涉仪完成了标定用数据的测量,通过3-RPS并联机构运动学逆解和各铰链的几何标定参数,得到动平台的实际位姿.通过对标定前后的Z轴定位精度的检测及实际零件加工试验,验证了3-RPS并联机构运动学标定模型和方法的正确性和有效性.

Study on kinematic calibration method of 3-RPS parallel mechanism

Aiming at the kinematic accuracy issues of six-axis hybrid machine tools arisen from the structural parameter errors in its 3-RPS parallel mechanism,the main error factors affecting the geometric accuracy of the 3-RPS parallel mechanism are analyzed and the error model is given.The calibration model is established based on the dominating errors.Utilizing damped least square method,the nonlinear transcendental contradictory calibration equation sets are solved with multiple optimal iterations.Employing the measured data collected with a laser interferometry,the actual pose is acquired from the kinematic inverse solutions and calibrated parameters of joints.The correctness and effectiveness of the calibration model and corresponding method are verified through the Z-axis positioning accuracy comparison before and after calibration,and machining experiment of real parts.