Lightweight Modeling of Underwater Gliders and Nonlinear MPC Controller Design with Actuator Constraint

Abstract

In response to the problems of high nonlinearity and dimensionality of existing underwater glider models, as well as difficulty in designing effective engineering controllers, the composition and working principle of the motion mechanism of underwater gliders were first studied. By neglecting secondary influencing factors in the modeling process, lightweight modeling of underwater gliders was conducted to reduce model nonlinearity and complexity. The effectiveness of the lightweight model was demonstrated through comparative verification. Subsequently, according to the motion in the vertical plane, the dynamic equation was further simplified, and the advantages of low dimension and small calculation amount of the model were brought into play. The actual constraints of state and control variables were introduced, and a realistic predictive attitude control algorithm for a real-time linearized model was designed. The numerical simulation results show that under the two common working conditions of ±17.4° and ±22.5° for underwater gliders, the control algorithm based on the lightweight model proposed in this paper can quickly track the desired attitude, and the rise time and steady-state settling time are improved by more than 70% compared with traditional controllers.

Keywords

• underwater glider
• lightweight modeling
• predictive control of model