The Trajectory Planning And Control Of 3-dof Parallel Manipulator With Limbs Of Embedding Structures

The control performance of manipulators is very important for their efficiency and operation precision,trajectory planning and trajectory tracking are two important aspects of the control performance of manipulators.The main job of this paper is to complete the trajectory planning and the design of the controller of a 3-dof parallel manipulator with limbs of embedding structures that is used to transfer wafer.It can improve the efficiency and operation precision based on the constraint conditions,to meet the requirements of high efficiency and high precision of wafer transmission.Firstly,the development status of wafer transmission manipulators,the trajectory planning and the controller of manipulators are summarized briefly.And the structure of the 3-dof parallel manipulator with limbs of embedding structures is analyzed.Secondly,based on the comparative analysis of trajectory planning methods,a trajectory planning method of improved polynomial interpolation is proposed in joint space.Which can obtain the optimal time under the premise of reducing the impact,and the optimal time is solved by using sequential quadratic programming strategy.The simulation shows that the trajectory planning method is effective.Finally,in order to track the target trajectories well,the dynamic model of the 3-dof parallel manipulator with limbs of embedding structures is established.We know that the system is a coupled nonlinear system through analyzing.In consideration of the influence of the uncertain external disturbance on the motion of manipulators and the advantages and disadvantages of various control methods,sliding model variable structure control is chosen.The simulation of the trajectories obtained by planning shows that the controller could track the expected trajectories well.And the controller of the manipulator has good robustness when some interference occurs in the system.