Abstract:

To be aimed at the characteristics of the underwater vehicle which has a strong nonlinearity, strong coupling, multiple input and output, complex hydrodynamic action and attitude changes severely, a nonlinear dynamic inversion control system is designed in this paper to solve the limitations caused by ignoring the nonlinear factors in the linear process of the design method of the traditional controller. Through the design of the slow loop attitude controller and the fast loop attitude controller, the problems that the underwater vehicle has nonlinear, strong coupling, multiple input and output are solved,the sta- bility of controller have been proven by Lyapunov stability analysis. The steady-state time is 1s and the o- vershoot is 4%by tracking unit step signal in this control method, it has a larger increase than the dynam- ic characteristics by PID control. The results of nonlinear control system simulation show that the control- ler for the uncertainty of 依30% hydrodynamic parameters has certain robustness.

Key words: control theory, underwater vehicle, nonlinear dynamic inversion, multiple input and out- put, fast/ slow loop attitude controller