Novel Observer-Based Robust Guaranteed Cost Controller Design for Supercavitating Vehicle with Nonlinear Fin Model

Numerical studies of full-state measurable longitudinal control of supercavitating vehicles have been conducted extensively, while the operating conditions where only noisy longitudinal displacement and pitch angle information are available have not attracted much attention, the nonlinear characteristics of fins have been neglected in previous studies as well. In order to achieve the stability control of the vehicle under the above conditions with disturbances and uncertainties, this paper establishes an FTCESO-based optimal guaranteed cost control synthesis under nonlinear fin model and conducts simulation verification. First, referring to the existing research on fin hydrodynamics, the update equation of the fin effectiveness in the dive plane is established to describe the nonlinear characteristics of the fin part dynamics in the model. Then, a full-state optimal guaranteed cost controller based on Lyapunov function and FTCESO with nonlinear feedback characteristics are respectively designed. They are combined and configured on the vehicle to stabilize uncertainties and disturbances. Finally, corresponding numerical simulations are implemented to illustrate that the closed-loop system configured with this control strategy has considerable efficiency of depth tracking and robustness against a certain degree of white noise.