Sliding Mode Control under Wave Disturbances for an AUV Using Nonlinear Observer Method

Abstract

This paper mainly presents that the influence from high-frequency wave disturbances to the motion of the AUV when it operates in shallow water. To solve the issue above, a nonlinear observer is proposed to derive the disturbance information of wave by estimating the shallow water wave's velocities and AUV's relative velocities from position and attitude measurement. With the observer estimates, the position errors in X, Y, Z directions are obtained by the velocity errors in surge, sway and heave. Meanwhile, a sliding mode controller is designed to make AUV keep stability while moving in the three dimensional space. Simulation results demonstrated that the proposed method is effective to eliminate wave disturbance and performs well.