Nonlinear ℋ∞ state and output feedback control schemes for an autonomous underwater vehicle in the dive plane

Abstract

This paper addresses the development of a nonlinear ℋ∞ diving control algorithm for an autonomous underwater vehicle. It employs both state and output feedback control techniques in designing a nonlinear ℋ∞ controller such that the autonomous underwater vehicle tracks the desired depth profile. The diving control problem is formulated as a disturbance attenuation problem, in view of achieving the desired performance by attenuating the internal as well as the external disturbances by ensuring internal stability and robustness. Two Hamilton–Jacobi–Isaacs inequalities have been formulated in the form of a Taylor series technique to determine solutions to the control algorithms. The solution of the first Hamilton–Jacobi–Isaacs inequality renders a state feedback control law whereas the second inequality is exploited to design a nonlinear observer for estimating the autonomous underwater vehicle states in order to realize an output feedback controller. These control algorithms are implemented firstly using the MATLAB/Simulink environment and then, the experimental validation of the developed control algorithm has been performed in order to ensure the effectiveness of the control scheme.