Research on Anti-Interference Nonlinear Adaptive Control Method for Autonomous Underwater Gliders

Wen-Qing Zhang,Liang-Long Da,Wen-Long Wang,De-Yan Tian,Qin-Dong Sun,Wen-Jing Chen,Xinggang Yan

doi:10.1155/2021/9998061

Abstract

In this paper, the characteristics of underactuation are analyzed according to the working principle of underwater glider, a complete 6DOF model of underwater glider is established, and the error equation of 3D path tracking is given. Based on the line-of-sight navigation method in three-dimensional space, the nonlinear adaptive control strategy is designed, and the roll angle control law, pitch angle control law, and depth control law of underwater glider are given. The tracking error of underwater glider is proved to be convergent by Lyapunov stability theorem. Finally, the results of marine experiments verify that the nonlinear controller designed in this paper can overcome the influence of constant current disturbance under certain conditions and has good robustness and good tracking effect under different ocean current sizes and course angles. Of course, one control method cannot be applicable to all sea conditions. When the angle between the size and direction of the ocean current exceeds a certain value, the tracking control of the underwater glider will show obvious divergence. Therefore, the stability range against the interference of the sea current is given in this paper.

Highlights

Underwater gliders have the advantages of long endurance and low energy consumption and can be applied to a variety of complex sea conditions
When the size of ocean current is 1.0 kN and the angle between it and the set course is increased to 10°, the critical oscillation phenomenon will appear in the yaw angle control. erefore, the stable range of the nonlinear adaptive control method designed in this paper against the ocean current interference is within 1.0 kN of the ocean current size and within 10° of Heading angle
Combined with the line-of-sight navigation method, an underactuated path tracking model of underwater glider is established and a nonlinear adaptive controller is designed. e roll angle control law, pitch angle control law, and depth control law of underwater glider are given. rough a large number of sea experiments, the control effect of underwater glider path following under different ocean current sizes and directions is analyzed

Summary

Introduction

Underwater gliders have the advantages of long endurance and low energy consumption and can be applied to a variety of complex sea conditions. To solve the problem of 3D path tracking control for underactuated unmanned underwater vehicles, Hongjian et al [6] designed a linear control term stabilized position tracking system in the form of tracking error feedback gain. A mathematical model of underactuated underwater glider is established and a nonlinear controller is designed under the condition of ocean current interference. The attitude adjustment mechanism changes the position of the center of gravity by moving the internal weight so that the glider can reach the desired attitude angle. During the dive, it glides forward and down, using hydrodynamic forces on its horizontal and vertical fins, while mission sensors measure data.

Nonlinear Controller Design

Stability Analysis

Stable region

Conclusions