基于四阶矩估计的机器人运动可靠性分析

Reliability analysis of manipulator based on fourth-moment estimation

为了研究串联型机器人的连杆尺寸偏差和关节间隙对运动可靠性的影响,将机器人运动路径离散成一系列插补点,有效的运动路径要求每一个插补点的位置误差均在精度范围之内.以离散点的位置误差为随机变量,通过研究路径中所有离散位置点误差的极值分布,基于最大熵原理建立机器人系统的功能函数.采用四阶矩估计法,对机器人的可靠性进行计算.与传统的一阶可靠性方法、一次二阶距估计法及Monte Carlo模拟进行对比分析.结果表明,采用四阶矩估计方法能够提高计算精度,显著缩短计算时间.

The trajectory is decomposed into a series of discrete path points in order to analyze the effect originated from linkage dimension deviations and joint clearances of the manipulator to the kinematic reliability.The safe trajectory can be obtained since all the positional errors of the path points are less than the required tolerance.The positional error of each independent discrete point was considered as the random variable.The extreme value distribution of the positional error of all the discrete points in the trajectory was analyzed.Then the performance function of the manipulator was established based on the maximum entropy principle.The fourth-moment reliability method(FMRM)was applied to estimate the kinematic reliability.The results obtained from the first-order reliability method(FORM),the first-order secondmoment method(FOSM)and Monte Carlo simulations(MCS)were used as the benchmarks for a comparative study.The efficiency and accuracy of the FMRM were improved,and the computation time was shortened.