Design of sliding mode controller for ship anti rolling tank test platform

The ship anti-rolling tank test platform is a specific designed synthesis system used to imitate the ship´s movement in the sea waves. An electro-hydraulic servo system featuring high accuracy and fast response is employed. This latter has highly nonlinear phenomena such as fluid compressibility, the flow pressure relationship and dead band due to the internal leakage and hysteresis. Usually, conventional controllers are adopted because of theirs simplicity, however these control methods could not get high performances, because of the nonlinearity of the system, its modeling error and uncertainties. The application of nonlinear robust control techniques is a necessity for successful operation of electro-hydraulic systems. Among these techniques, sliding mode control have attracted considerable attention because it provides a systematic approach to the problem of maintaining stability and consistent performance in the face of modeling imprecision and disturbances.