Abstract: Ship motion simulator is subjected to disturbance caused by the tested equipment, which affects the control accuracy of the simulator. Through analysis of the dynamics of the system, an adaptive disturbance observer is designed to estimate the disturbance online, and then compensation is made in the controller. The difficulties of the hydraulically controlled ship motion simulator in accurate control are analyzed, and a robust controller is designed to overcome the disturbance caused by parametric uncertainty and unmodeled uncertainty. The backstepping method is adopted to develop the integrated nonlinear controller. The controller is proven to be asymptotically stable via Lyapunov analysis. The experiment results performed with the ship motion simulator demonstrate the effectiveness of the approach. And the performance of the system is improved in comparison to using a proportional integration differential (PID) controller.

Key words: 6-DOF, Compensation, Disturbance observer, Motion simulator, Parallel platform, Trajectory tracking