Sliding Mode Acoustic Servoing for an Autonomous Underwater Vehicle

Abstract

24th Annual Offshore Technology Conference (OTC) in Houston, Texas, May 4-7, 1992Currently in use at the Naval Postgraduate School is a fully functional experimental autonomous underwater vehicle (AUV). The vehicle serves as a test bed for research in autonomous control, autonomous obstacle avoidance, automatic fault detection, guidance and control at slow speed. It measures over seven feet (two meters) in length and weights about 430 pounds (215 kg). Maneuvering control is provided by four rudders and dive planes, has twin propulsion motors, and onboard sensors for speed, depth, angular rates and positions and four ultrasonic sensors for range information. All shipboard action is controlled by a 68030 microprocessor running under an OS-9 operating system and a G-96 bus with code written in 'C' language. All systems are powered by a lead acid gell batteries for a test mission duration of about two hours. This paper presents some experimental modeling results upon which computer simulations of the dynamic positioning performance are based. Details are given of the vehicle modeling, the influence of thruster dynamic lags, Sliding Mode control design including integral control for the compensation of ocean current effects, and a Kalman filter design for the estimation of target range and velocity from noisy sonar data. The filter can remove transient fault anomalies which are common in sonar data.Naval Postgraduate School Direct Research FundOffice of Naval TechnologyNaval Postgraduate School Direct Research FundOffice of Naval Technolog