并联机构的运动学多目标轨迹规划方法

Method of Multi-objective Trajectory Planning of Parallel Mechanism Based on the Kinematics

提出了一种能够满足装配任务对多种性能需求的并联机构无奇异轨迹规划方法。以运动学分析为基础,证明了一定位姿条件下实现并联机构无奇异轨迹规划的充要条件。然后利用五次B样条曲线对并联机构末端轨迹进行了参数化表达。选取了与装配任务相关的三个运动学性能指标,即总调姿时间,各支链急动度和调姿难易度,并定义为目标函数以评价轨迹的优劣。在仿真实例中,利用人工免疫算法求解了多目标轨迹优化模型并得到了末端轨迹中的36个B样条参数。最后利用平均最优解的评价方法得到了满足装配任务需求的并联机构末端最优轨迹及各支链轨迹。

A singular-free trajectory planning method based on the kinematics is proposed to meet the various requirements of the assembly task. On the basis of kinematic analysis of parallel mechanism, a sufficient and necessary condition is proved for realizing the singular-free trajectory planning of parallel mechanism under certain pose conditions. Then a five-order B-spline curve is employed to parameterize the trajectory of the end-effector of the parallel mechanism. Three kinematic indexes related to the assembly task, that is, the total adjustment time, the jerk of each link and the difficulty of aligning the pose of the end-effector, are selected and defined as three objective functions to evaluate the performance of the trajectory. In a simulation case, the artificial immune algorithm is used to optimize the multi-objective optimization model of the parameterized trajectory and thirty-six B-spline parameters of the trajectory are obtained. Finally, the optimal trajectory of the parallel mechanism and each link satisfying the requirement of assembly task are obtained by means of average optimal evaluation method.