Drift Suppression Control Based on Online Intelligent Optimization for Planar Underactuated Manipulator With Passive Middle Joint

We consider the position control problem of the planar 3R manipulator with the middle passive joint, whose dynamic constraint is caused by the second-order non-holonomic characteristic. A drift suppression control method with two stages is proposed for positioning the system. First, we give the dynamic model and the target angle of the system solution algorithm. Then, the controllers are designed to make the active links reach to their desired states, and the second link is rotating freely caused by the drift. So, the parametric trajectory is planned to suppress the drift of the second link and tracking this trajectory can makes all links reach to their desired states. Next, we use the differential evolution algorithm to search for the suitable parameters of the parametric trajectory taking the coupling constraints among all links. Then the controllers are designed to track the planned trajectories, so that all links can be controlled to the desired states simultaneously. Finally, numerical simulation results illuminate the effectiveness of the proposed method.