Trajectory planning and tracking control for 6-DOF Stanford manipulator based on adaptive sliding mode multi-stage switching control

This article intends to investigate the trajectory planning and tracking control for six-degrees-of-freedom (6-DOF) Stanford manipulator consisting of 3-DOF mechanical arm and 3-DOF spherical wrist. By using Denavit-Hartenberg (DH) method, the Euler-Lagrange equations of motion of mechanical arm subsystem and spherical wrist subsystem are established, respectively. A new version of backstepping-based adaptive sliding mode controller is proposed for trajectory tracking of each subsystem. In order to grasp an object from one point to another, a special smooth continuous trajectory is planned by inverse kinematics analysis which transforms the position of the end-effector in the task space to the joint position in the joint space. After that, a multi-stage switching control strategy is proposed to achieve trajectory tracking control. Simulation results are provided to demonstrate the performance of the proposed control strategy.