Dynamics And Control Of A Planar Flexible Parallel Manipulator With Redundant Actuation

This thesis presents the research work about dynamic modeling of a planar flexible parallel manipulator with redundant actuation, and control of the manipulator with several approaches and using PZT for vibration attenuation. The Lagrangian formulation is used to derive the equations of motion of the flexible-link parallel manipulator with redundant actuation. The constraint forces are eliminated and obtain the minimum number of equations of motion. Based on the dynamic model, many dynamic control algorithms designed for serial flexible manipulators can be applied to the parallel flexible manipulators. Many advantages of redundant actuation are confirmed by numerical simulation. Redundant actuation can eliminate singularities, and improve the stiffness and accuracy of parallel manipulators. For flexible parallel mechanism, redundant actuation can damp vibration of flexible-link. Piezoelectric actuators are used for residual vibration attenuation, resulting in high positioning accuracy and fast movements. The aim of trajectory tracking control of flexible mechanism is high tracking accuracy and simultaneous vibration attenuation. It is not easy for active joints to control the stiff movements of flexible manipulators and damp vibration simultaneously. In this thesis, the torque provided by active joints is responsible for stiff movements of a flexible parallel manipulator, rigid model of the manipulator is regarded as the nominal system. PZT is used to damp vibration of flexible-link, making the error between flexible manipulator and nominal system small, resulting in stability of the system. The control scheme reduces the time of calculating for real time control.