Kinematics and Performance Analysis of the 2T1R/1T2R Reconfigurable Decoupled Parallel Mechanism

Based on the reconfigurable revolute (rR) pair, a reconfigurable decoupled parallel mechanism is proposed, which is composed of three serial chains. Traditional serial chain 1 and 2 are of types PRRR and URC, respectively, where P denotes a prismatic pair, R denotes a revolute pair, U denotes a universal pair, and C denotes a cylindric pair. The reconfigurable serial chain 3 can switch between PRRP and RRPP configurations by changing the axis of reconfigurable pair rR, thus enabling the parallel mechanism to switch between two motion modes of 2T1R (where R represents rotation and T represents translation) and 1T2R. By investigating the relationship between the mechanism's motion output, input, and the Jacobian matrix, it is verified that the parallel mechanism is a completely decoupled mechanism in the 2T1R motion mode and a partially decoupled mechanism in the 1R2T motion mode. Finally, the performance indexes of the mechanism in both motion modes were discussed using screw theory, and the dimensions of the mechanism were optimized in scale, thereby enhancing the motion performance of the parallel mechanism. The results indicate that the decoupling characteristics of the reconfigurable parallel mechanism have significant advantages in both 2T1R and 1T2R motion modes, providing a theoretical basis for the study of reconfigurable and decoupled parallel mechanisms.