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Title: A guidance-control approach applied to an autonomous underwater vehicle
Author: Jantapremjit, Pakpong
ISNI:       0000 0001 3589 1737
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2008
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This thesis is concerned with the guidance and control problem for autonomous homing and docking tasks using an autonomous underwater vehicle. The tasks will play a key role in long-term underwater applications in the future. Current technology allows most vehicles capable of short-term operation. Because of limitations of energy storage and sensor capability, underwater vehicles considered in large networks are unable to operate continuously in completing a large task assignment for extended periods of time. To extend a large scope of the missions, autonomous homing and docking tasks are therefore required allowing a vehicle to automatically return to the docking station and then recharge its own battery and exchange data before continuing the operations. The thesis describes work towards guidance and control systems to enable a nonholo- nomic torpedo shaped underwater vehicle to perform automatic homing and docking preparation tasks. The artificial potential field and the vector field path generation methods construct the predefined trajectory by extracting position information from surrounding sensor nodes. Thus, the predefined path leads an AUV relatively close to the docking station with obstacle avoidance. With an enhanced model, the switching weighted vector field technique applies a set of varying weights. This technique shapes a trajectory which a docking preparation manoeuvre can improve. The Line-of-Sight guidance law with the control system then forces the vehicle to follow its predefined path to the desired destination with the proper orientation at the dock. The sliding mode controller is designed for both heading and depth control. A subsystem using sliding mode is applied to obtain a robust controller for handling nonlinear system behaviours. Due to a problem of chattering effects caused by the standard sliding mode control, the high-order sliding mode control solves it with success whilst its main characteristic is maintained. To improve performance of the controllers, the optimal control technique via state-dependent Riccati equation is explored. Finally, a novel method integrates the guidance and control laws with optimal waypoint guidance algorithm for smooth commanded transitions. Based on the Lyapunov stability theorem, the guidance-control system guarantees stability of tracking. The feasibility of this approach is analytically formulated and the simulation is numerically demonstrated using an autonomous underwater vehicle.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available