可轮换用动平台的运动解耦三自由度并联机构拓扑设计与性能分析

Topological Design and Performances Analysis of Kinematically Decoupled 3-DOF Parallel Mechanism with Alternately Used Moving Platforms

摘要:

首先提出一种可轮换用动平台的部分运动解耦三自由度并联机构，该类机构在工作过程的不同阶段可轮换使用两个不同的动平台以产生两平移一转动（2T1R）和三平移（3T）两种不同模式的输出运动，最终实现不同的工艺操作，可视为一种新的两模式输出运动机构。进一步，分析该三自由度并联机构在两种不同模式下的拓扑学、运动学与动力学性能，包括以方位特征（POC）、自由度（DOF）和耦合度（k）为内容的拓扑性能分析，基于其拓扑特征的机构符号式位置正反解的求解，基于位置正解的机构工作空间分析，以及基于位置反解的机构奇异位置分析；基于虚功原理序单开链法的机构动力学建模及其驱动力曲线的求解。然后，将可达工作空间作为优化目标，对机构的尺寸进行优化设计。最后，对该机构用作激光切割工艺的执行机构，并对2T1R和3T两种模式应用场景的概念设计进行阐述。本研究为可轮换用动平台的并联机构的设计、分析与潜在应用提供了理论依据，也拓展了多模式机构的概念、设计方法与应用范围。

Abstract:

A class of three-degree-of-freedom parallel mechanisms was firstly proposed with alternately used moving platforms, the innovation of which lay in the adoption of alternately used moving platforms structure. This type of mechanism can alternately use two different moving platforms during different stages of the working process to generate two distinct modes of output motion—two translations and one rotation (2T1R) and three translations (3T)—thereby achieving different process operations. It can be regarded as a novel dual-mode output motion mechanism. Furthermore, the topological, kinematic, and dynamic performance of this three-degree-of-freedom parallel mechanism under the two different modes was analyzed. This included topological analysis based on position and orientation characteristics (POC), degree of freedom (DOF), and coupling degree (k);the derivation of symbolic forward and inverse position solutions based on its topological characteristics;workspace analysis based on forward position solutions;singularity analysis based on inverse position solutions;dynamic modeling of the mechanism using the virtual work principle and the ordered single-open-chain method, along with the solution of its driving force curves;and the optimization design of the mechanism’s dimensional parameters with the reachable workspace as the optimization objective. Finally, the application of this mechanism as an actuator in laser cutting processes was discussed, and the conceptual design for two process application scenarios—material handling in the 2T1R mode and cutting in the 3T mode—was elaborated. The research result can provide a theoretical basis for the design, analysis, and potential applications of parallel mechanisms with alternately used moving platforms, while also expanding the concept, design methods, and application scope of multi-mode mechanisms.