Sliding mode end point trajectory control of a two link elastic manipulator

A variable structure (VS) system scheme for controlling the end effector trajectory of a two-link flexible robotic arm is introduced. Since control of the actual tip position leads to unstable zero dynamics, control of points in the neighborhood of the tip is considered. An output is chosen as the sum of the joint angle and tip elastic deformation times a constant factor for each link. For the chosen output, a discontinuous output control law is derived based on the VS theory. The control law thus derived accomplishes the desired trajectory tracking of the output. A linear stabilizer is designed using the pole assignment technique for the final capture of the terminal state and stabilization of the elastic modes. Simulation results showing that, in the closed-loop system, large maneuvers can be performed in the presence of payload uncertainty, indicating the robustness of the controller are presented