低耦合度PRPaR-2CPR并联机器人机构设计与运动学分析

提出一种支链含平行四边形结构的新型PRPaR-2CPR并联机器人机构,机构由1条PRPaR支链和2条CPR支链构成,具有结构简单、耦合度低、刚度高特点。基于方位特征(POC)方程的并联机构拓扑设计理论和方法,对自由度和运动性质进行分析计算,利用杆长约束条件建立运动学方程,计算得到逆解表达式,同时得到正解数值解。另外,根据雅克比矩阵分析出奇位性存在条件,通过位置逆解表达式,运用极限边界搜索法分别得到工作空间和运动灵巧度性能图谱,绘制相应性能图谱加以分析,期望在有限的操作空间范围内获得更好的运动灵活性性能。以任务工作空间内的全局灵巧度作为优化目标,选择遗传优化算法进行结构参数的优化设计。优化后的任务工作空间内灵巧度性能得到极大的改善,使此并联机构运动性能得到改善。

Design and Kinematics Analysis of Low Coupling PRPaR-2CPR Parallel Robot

A new type of PRPaR-2CPR parallel robot mechanism with parallelogram branch chain was proposed.The mechanism was composed of one PRPaR branch chain and two CPRs.It had the characteristics of simple structure,low coupling and high stiffness.The topological design theory and method of parallel mechanism based on the POC equation were used to analyze and calculate the degree of freedom and kinematic properties.Kinematic equations were established using the constraint conditions of link length,and the inverse solution expression was obtained through calculation.At the same time,the positive numerical solution was obtained.In addition,according to the calculation and analysis,the existence conditions of singularity were obtained.Through the inverse solution expression of position,the limit boundary search method was used to obtain the performance maps of workspace and motion dexteri ty respectively,and the corresponding performance maps were drawn for analysis.Finally,it was expected to obtain better motion flexibility performance in the limited operating space.With the global dexterity in the task workspace as the optimization goal,genetic optimization algorithm (GA) was selected to optimize the structural parameters.The dexterity performance in the optimized task workspace has been greatly improved,so the motion performance of this kind of parallel mechanism is improved.