Motion control of an oscillatory-base manipulator using sliding mode control via rotating sliding surface with variable-gain integral control

In this paper, we present a motion control method of oscillatory-base manipulators, which are associated with mechanical systems installed on vessels or ocean structures. The typical property of such systems is strong and persistent disturbance due to the base oscillation to be overcome. Therefore, we attempt to exploit the sliding mode control (SMC) concept which is known to be a powerful tool to develop a robust control system against disturbances and model uncertainties. Specifically, we propose a novel approach based on SMC by introducing a nonlinear sliding surface with variable-gain integral control. We address control system design and stability analysis for the proposed SMC, and demonstrate its control performance by simulations. The results show that the proposed control method can achieve successful control performance for oscillatory-manipulators and further exhibits advantageous features with respect to control performance and control inputs when compared with the conventional SMC.