Motion analysis and fuzzy-PID control algorithm designing for the pitch angle of an underwater glider

Abstract

Underwater gliders are used for deep-water gliding to observe large areas with minimal energy consumption. The pitch angle of the underwater glider is an important control parameter. This study involved designing a fuzzy-PID controller for the pitch angle of an underwater glider based on hydrodynamics analysis. The formula of pitch angle is obtained and a system identification method was used to identify the transfer function based on the time-domain equation and initial experimental data. The fuzzy-PID control algorithm was used to design the controller. Lake and sea trials indicated that the minimum overshoot reached 0% and the settling time was about 34s when the change of the angle was 15 • . The minimum steady-state error was 0.8 • . These advantages could reduce the consumption of energy and improve the accuracy of gliding trajectory. Therefore, this control algorithm should be applied to control the pitch of the gliders.