Development of state space models for underwater gliders equipped with embedded actuators in vertical and horizontal planes

Abstract

Nowadays, underwater gliders (UGs) are known as efficiency vehicles to observe and quantify water properties concerning marine environments, seabed characteristics, and water depths. The development of appropriate dynamic and state space models is necessary for designing an effective control system. This study aims to develop state space models for UGs equipped with embedded actuators based on a non-linear dynamic model that takes into account the hydrodynamic characteristics of the body and wings. The method involves utilizing sensitivity analysis and assumptions to construct two distinct state space models, along with the linearization of the non-linear model in horizontal and vertical plane motions. The presented models are compared with simulation and experiment results to enhance validity. Furthermore, the linear models, when compared with the non-linear model and experimental tests, exhibit suitable performance. The results indicate the maximum observed differences of −9.7% in the period of the first cycle, −12.02% in the yaw angle, and 15.5% in the advance length between linear and non-linear models during zigzag, course-changing, and helical maneuvers, respectively. Through the presented linear models, LQR controllers are designed for the SUT glider and are subjected to testing in a real-world environment, experiencing suitable performance.