Two-Time Scale Control of a High Speed Planar Parallel Manipulator with Structural Flexibility

This paper presents two-time scale dynamic models of a high speed, lightweight parallel manipulator modeled with structural flexibility of its links. Connected by multiple closed loop chains, the platform of the parallel manipulator exhibit complex dynamic motions. Moreover, flexible deformation of lightweight links could propagate vibration to the platform in high-speed operation, that make it difficult to design a precise control system without additional vibration damping actuators, such as a smart material. Based on the two-time scale models, the composite controller, consisting of a trajectory follower for the slow-time scale and an active structural vibration damper for the fast-time scale dynamics, is proposed. Simulation results show that the composite control scheme can make the platform follow a given desired trajectory while damping out structural vibration of links.