Theoretical analysis and experimental verification of dynamic characteristics of spatial parallel mechanisms considering irregular wear clearance of revolute joints

In order to master the impact of irregular wear clearances on the dynamic response of spatial parallel mechanisms, it is essential to conduct a detailed study on the dynamic characteristics of spatial parallel mechanisms with joints featuring irregular wear clearances. Currently, the majority of research concerning mechanisms with joints featuring irregular wear clearances is mainly centered around planar mechanisms. In contrast, studies on spatial parallel mechanisms involving multiple revolute joints with wear clearances are rather scarce. Moreover, the research on the dynamic responses of mechanisms with wear clearances primarily focuses on the theoretical level, but the experimental investigations are relatively rare. Consequently, considering irregular wear in revolute clearance joints, this study adopts a combined theoretical and experimental methodology to explore the dynamic characteristics of the 3-RRPaR (R denotes a revolute pair, P denotes a prismatic pair, Pa denotes a parallelogram mechanism) spatial parallel mechanisms. Additionally, a dynamic model for the irregular wear clearance of revolute joints has been deduced based on Archard wear theory. This study has successfully formulated a dynamic model for spatial parallel mechanisms featuring revolute joints with irregular wear clearances. Based on this model, this study conducted an in-depth analysis of the specific impacts of mechanism trajectory, clearance size, and operating speed on the dynamic responses of such mechanisms. To verify the accuracy of the theoretical model and the validity of the dynamic characteristic analysis, we specifically constructed an experimental prototype of the 3-RRPaR parallel mechanism. This series of research outcomes has established a robust theoretical foundation for predicting the operational lifespan of parallel mechanisms with wear clearances.