一种2R1T远中心运动并联机构性能分析及尺度优化

Performance Analysis and Dimensional Optimization of a 2R1T Parallel Mechanism with Remote Center of Motion

与串联机构相比,并联机构具有刚度好、精度高、结构稳定紧凑等优点,适用于外科手术领域。提出一种可用于微创手术本体结构的两转动一移动远中心运动(Remote Center of Motion,RCM)(5R)O C-URR并联机构,具有部分运动解耦特性。建立机构位置分析模型,推导出机构位置逆解表达式;在此基础上,针对微创手术工作任务,定义机构期望工作空间。应用局部运动/力传递性能评价指标,给出机构期望工作空间内平均传递指标定义及计算方法。以平均传递指标最大化为目标,建立机构尺度参数约束优化模型,并应用加速灰狼优化(Accelerating Grey Wolf Optimization,AGWO)算法求解该问题。数值实例测试显示,AGWO算法求解约束优化问题的综合性能优于对比算法。机构优化设计结果表明,给出的优化模型和算法可行有效。研究结果为该机构的实际应用奠定了理论基础。

Compared with serial mechanisms,parallel mechanisms have the advantages of good rigidity,high precision,stable and compact structure,which are suitable for the field of surgery.A(5R)OC-URR parallel mechanism with two rotational and one translational degrees of freedom and remote center of motion(RCM)is proposed which can be used for the body structure of minimally invasive surgery and has the characteristics of partial motion decoupling.The position analysis model of the mechanism is established,and the analytical expression of position of the inverse solutions is derived.On this basis,the desired workspace of the mechanism is defined for the task of minimally invasive surgery.Using the evaluation index of local motion/force transmissibility,the definition and calculation method of average transmission index in the desired workspace of the mechanism are given.Aiming at maximizing the average transmission index,a constrained optimization model of mechanism dimensional parameters is established,and the accelerating grey wolf optimization(AGWO)algorithm is employed to solve the problem.The test of numerical examples shows that the comprehensive performance of AGWO algorithm in solving constrained optimization problems is better than that of the compared algorithm.The results of mechanism optimization design show that the optimization model and algorithm are feasible and effective.The research work in this study can lay a theoretical foundation for the practical application of the mechanism.