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针对一台平面3自由度并联机床的运动学标定,提出一种基于最少参数线性组合的分步运动学标定方法.该方法利用并联机器多参数耦合误差传递系统中的参数线性组合映射关系,将一般运动学标定中参数的误差建模、辨识和误差补偿,改变为参数线性组合的误差建模、辨识和误差补偿.首先由最少参数线性组合的4个定理进行辨识性分析,确定出影响机床终端绝对和相对精度的最少参数线性组合;然后给出工程实际中常用的基本绝对测量方式和基本相对测量方式,逐一进行最少参数线性组合的辨识性分析,抗干扰指标的抗扰动性能计算,兼顾测量成本的条件下,设计出最少参数线性组合的分步测量方案、分步辨识和分步误差补偿方案,完成运动学标定.最终的实验结果证明这种方法具有如下优点:(1)消除了其他无关参数的影响;(2)反映了误差传递中的参数线性组合映射关系,提高了参数辨识的准确性;(3)方法简洁高效,最终的机床精度已经接近测量扰动精度.因此,该方法不仅可用于这台平面3自由度并联机床,也可适用于其它运动学非线性弱的并联机器.
Aiming at the kinematic calibration of a planar 3-DOF parallel machine tool, a step-by-step kinematic calibration method based on the least parameter linear combination is proposed. By using the linear combination of parameters in the multi-parameter coupled error transfer system of parallel machine, General kinematic calibration of the parameters of the error modeling, identification and error compensation, to change the parameter linear combination of error modeling, identification and error compensation.Firstly, the linear combination of least-linear four theorems for identification analysis to determine the impact of machine tools Terminal absolute and relative accuracy of the minimum parameters of the linear combination; and then given the engineering practice of the basic absolute measurement methods and the basic relative measurement method, one by one for the linear combination of the least parameter identification analysis, anti-disturbance index anti-disturbance performance calculation, taking into account The method of step-by-step measurement with minimum parameter linear combination, step-by-step identification and step-by-step error compensation scheme are designed and the kinematic calibration is completed under the condition of measurement cost.The final experimental results show that this method has the following advantages: (1) Other irrelevant parameters; (2) reflect the error propagation in the linear combination of parameters mapping Which improves the accuracy of parameter identification. (3) The method is concise and efficient, and the final precision of the machine tool is close to the accuracy of the measurement disturbance.Therefore, this method can be used not only for the plane 3 DOF parallel machine tool, but also for other kinematics Nonlinear weak parallel machines.