Robust adaptive super-twisting sliding mode formation controller for homing of multi-underactuated AUV recovery system with uncertainties.

This paper is concerned with the homing process in which a multi-underactuated AUV recovery system tracks the moving mother submarine in finite time in the presence of uncertain hydrodynamic parameters and unknown environmental disturbances. In the homing stage, underactuated AUVs and the moving mother submarine are treated as followers and the leader, respectively. The multi-underactuated AUV system finite time homing problem is converted to the leader-following finite-time formation control problem. The proposed leader-following formation strategy requires only the position information of the leader. The velocity of the leader can be designed as an additional degrees of freedom to stabilize position errors of the formation. A novel robust adaptive super-twisting sliding mode formation controller (ASTASMC) is proposed, specifically the super-twisting algorithm (STA) with adaptive uncertainty estimation. Wherein, the robust adaptive law can compensate for uncertainty with unknown upper bound in real time. Therefore, the proposed controller can not only enhance the tracking accuracy but also reduce the chattering. In addition, the finite-time convergence of estimation errors and tracking errors is rigorously proved. Finally, simulation results demonstrate the effectiveness of theoretical results.