ONLINE SYSTEM IDENTIFICATION AND CONTROL OF AN AUTONOMOUS UNDERWATER VEHICLE

Abstract

THIS DISSERTATION ADDRESSES THREE CHALLENGES OF THE FLIGHT CONTROL SYSTEM OF AN AUTONOMOUS UNDERWATER VEHICLE (AUV). THE MAIN CHALLENGE IS THE CHANGING DYNAMICS CHARACTERISTIC OF AN AUV WHEN IT IS RECONFIGURED WITH DIFFERENT PAYLOADS. BY PERFORMING A COMPACT SET OF MANEUVERS, THE AUV?S DYNAMICS IS IDENTIFIED AND VALIDATED ONLINE. THE IDENTIFIED MODEL IS THEN USED TO ESTIMATE THE TURNING RADIUS AT DIFFERENT SPEEDS AND TO DESIGN A GAIN-SCHEDULED CONTROLLER. NEXT, AN INTERNAL ROLLING MASS MECHANISM IS DESIGNED TO ACTIVELY STABILIZE THE AUV?S ROLL MOTION, WHICH IS IMPORTANT DURING IDENTIFICATION AND UNDERWATER SURVEY ACTIVITIES. LASTLY, THE MINIMUM ACHIEVABLE SPEED OF AN AUV, WHILE MAINTAINING DEPTH, IS STUDIED. UNDER THE FRAMEWORK OF EXTREMUM SEEKING, WE DEVELOP AN ONLINE ALGORITHM TO DIRECT THE AUV TOWARD ITS MINIMUM SPEED AUTOMATICALLY WHILE PRESERVING DEPTH CONTROL. IN ALL CASES, WE VALIDATE THE PROPOSED METHODS THROUGH EXTENSIVE FIELD EXPERIMENTS.