Constraint-Embedded Velocity Analysis of Lower-DoF Parallel Manipulators to Remove Parasitic Motion .

This work presents a methodology to analyze the constraint and motion of the lower mobility parallel manipulators at the velocity level. The work also introduced a new method to detect the parasitic (dependent) motion at the moving platform. The approach follows the analytic method of obtaining the reciprocal screws for the motion and constrain of the manipulator. Moreover, a new 3 by 3 Jacobian matrix is achieved, parasitic motion is optimized, and a non -parasitic motion improved performance manipulator is introduced. The configuration that removes the parasitic motion from the manipulator workspace has poor performance. In order to enhance the performance of optimal configuration without altering its kinematic characteristics, the spherical joint in one of the limbs is decoupled. So, the performance is improved without allowing the parasitic motion to appear in its workspace. The file can be used independently or with the papers listed in the link below. 1) https://www.sciencedirect.com/science/article/pii/S0094114X21001671 2) https://www.mdpi.com/2076-3417/11/10/4690本研究提出了一种用于在速度层级分析低自由度并联机械手（lower mobility parallel manipulators）约束与运动的方法。本研究同时提出了一种可检测动平台处寄生运动（parasitic motion）的全新方法。该方法遵循通过求解机器人运动与约束的互易螺旋（reciprocal screws）以开展分析的解析路径。此外，本研究构建了全新的3×3雅可比矩阵（Jacobian matrix），对寄生运动进行了优化，并提出了一款无寄生运动且性能得以提升的并联机械手。仅将寄生运动从机械手工作空间中移除的构型，其性能表现欠佳。为在不改变最优构型运动学特性的前提下提升其性能，本研究对其中一条支链中的球铰（spherical joint）进行了解耦处理，由此在确保工作空间内不会出现寄生运动的同时优化了整体性能。本文件可独立使用，亦可配合下述链接所列的研究论文一同使用。1) https://www.sciencedirect.com/science/article/pii/S0094114X21001671 2) https://www.mdpi.com/2076-3417/11/10/4690