Investigation of the improved SDRE control strategy of an AUV based on the optimum of the energy

Energy is always the most limited resource when the AUVs carry on activities in the sea. When the AUV sails near the water surface, it will be disturbed by the sea waves and the AUV will undertake some motions that are not wanted. At last the resistance of the AUV will be increased, because of these not wanted motions. So it is urgent to minimize the resistance caused by the AUV motion so as to decrease the energy consumption on sail. Aim to this problem, in this paper we proposed a dynamic resistance model of AUV, when the AUVs sails in the sea. This model will be used as an evaluation index in the design of the motion control method. To obtain the stabilized position and decrease the energy consumption, the longitudinal model of AUV is built and an improved control method is proposed, which could solve the problem of nonlinear characteristic and parameter uncertainty of the model of AUV. As a result not only the pitch angle of the AUV is decreased by the improved control method efficiently, but also the resistance caused by the pitch motion. Simulation analysis verifies the correctness of the dynamic resistance model and control method.