Control of Lightweight Manipulators Based on Sliding Mode Technique

This chapter focuses on the dynamic control issues of lightweight robots as well as flexible joint robots. The goal is to increase the bandwidth and the accuracy of the trajectory tracking control. Besides the joint flexibility, the control design considers the dynamics of the electric motor in AC-form i.e. the three phase permanent magnet synchronous motor (PMSM). The final system model is a fifth order non-linear system. Based on the theory of integral sliding mode control a robust control approach for the trajectory tracking control of rigid-body robots is presented at first. This control approach has pole-placement capability despite system uncertainties. The controller is then used as the outer position controller for the control of flexible joint robots. To handle the joint flexibility, singular perturbation approach is employed, resulting in reference currents for the inner current control loop of joint motors. For the current control, sliding mode PWM technique is used to overcome the disadvantages of conventional open-loop PWM. The developed control algorithms are simple enough for practical implementation and verified by simulation studies based on a dynamic model consisting of a two-link flexible joint robot with two joint motors.