Synchronized Control Algorithm for the Precise Tracking of 4-SPS(PS) Type Parallel Manipulator

In precise tracking control system of parallel manipulator, the different of the dynamic characteristics of each actuator are the main reasons effect the precise tracking performance, that is, high-precision tracking control of parallel manipulator depends not only on the position accuracy of each actuator, but also on the dynamic characteristic synchronization of all actuators. This paper presents a synchronized control algorithm for the precise tracking control of 4-SPS(PS) type parallel manipulator by select a tracking error as a standardize which response slowest among all actuators (defined as the synchronization error). Compared with this standardize tracking error, sliding mode synchronous control is developed with feedback of the synchronization errors of tracking errors among actuators. The controller can stabilize the tracking of each actuator, and meanwhile synchronize all actuators' tracking so that both position and synchronization errors converge to zero. It is proved that the proposed scheme can guarantee global stability of the system by Lyapunov stability theory. Simulation results demonstrate the control algorithm is feasible and valid.