A feedback control strategy for improving the motion accuracy of underwater gliders in currents: Performance analysis and parameter optimization

Abstract

As a promising autonomous observation platform for ocean phenomena, underwater glider can achieve space motion by adjusting its net buoyancy and attitude. In some high accuracy exploration missions, underwater glider needs to move on a specific trajectory, and the position that the glider resurfaces should be accurate enough. In fact, many uncertain factors will affect the glider motion and reduce the motion accuracy, especially the current. In this paper, we present a feedback control strategy for improving the glider motion accuracy in currents. The feedback control is achieved by intermittently adjusting the movable mass block rotation amount, which is energy-saving. Especially, the feedback control strategy considers the force condition change of the glider in different water depths and the different motion states of the glider in currents. Besides, we introduce the surrogate models to calculate the adjustment time length of movable mass block rotation amount, which can ensure that the feedback control has a higher reaction speed. To verify the effectiveness of the above strategy, the dynamic model of underwater glider is established, and the model is validated by using experimental data. The simulation results under specific working conditions illustrate that the feedback control strategy can effectively improve the glider motion accuracy in currents. To achieve the optimal control, we further propose a method to optimize the relevant parameters of feedback control strategy, considering the multiple working conditions and the energy consumption metric. The simulation results under specific working conditions verify the effectiveness of proposed optimization method. The research works can provide certain guidance for the achievement of the glider precision operation.