Efficient modeling and integrated control for tracking and vibration of a lightweight parallel manipulator including servo motor dynamics

Abstract In the scenarios of high-speed operation, the bad elastic vibrations of lightweight manipulators readily arise, thus affect the overall motion of system even induce motion instability, which is a critical issue needing to be tackled appropriately. This paper concentrates on the efficient dynamic modeling and tracking/vibration integrated control for a lightweight parallel manipulator (LWPM) including servo motor dynamics. Firstly, a systematic methodology is proposed to establish the rigid-flexible coupling dynamics model (RFDM) of mechanical system possessing a modular feature, which can reduce the modeling effort. To alleviate computational burden, the RFDM is elaborately reduced to a concise model characterized by fewer generalized coordinates of system. Further, by integrating the simplified RFDM with the dynamics model of permanent magnet synchronous motor (PMSM), the electromechanical coupling dynamics model (ECDM) of system is formulated. On this basis, the ECDM is decoupled into two reduced-order subsystems by virtue of singular perturbation theory, and following that, a novel hybrid control strategy is proposed, in which a kind of task space-based proportional-integral robust sliding mode controller is designed for the slow subsystem while an quadratic optimal controller is designed for the fast subsystem. Ultimately, two simulation experiments are implemented to comprehensively investigate the dynamic performance of the presented hybrid control in comparison with the traditional joint-based PD feedback control. The results substantiate that both the excellent trajectory tracking precision of end-effector and vibration suppression can be achieved efficiently by the hybrid control, which lays a sound foundation for the application of the proposed approach in practice.