Fault-Tolerant Region-Based Control of an Underwater Vehicle with Kinematically Redundant Thrusters

Zool H Ismail,Ahmad ’A Faudzi,Matthew W Dunnigan

doi:10.1155/2014/527315

Abstract

This paper presents a new control approach for an underwater vehicle with a kinematically redundant thruster system. This control scheme is derived based on a fault-tolerant decomposition for thruster force allocation and a region control scheme for the tracking objective. Given a redundant thruster system, that is, six or more pairs of thrusters are used, the proposed redundancy resolution and region control scheme determine the number of thruster faults, as well as providing the reference thruster forces in order to keep the underwater vehicle within the desired region. The stability of the presented control law is proven in the sense of a Lyapunov function. Numerical simulations are performed with an omnidirectional underwater vehicle and the results of the proposed scheme illustrate the effectiveness in terms of optimizing the thruster forces.

Highlights

For several decades, extensive efforts have been dedicated to the development of autonomous underwater vehicles (AUVs) for subsea intervention/inspection, scientific exploration, and military purposes
The proposed dynamic region control scheme, where it is formulated in task space, aims to reduce the energy consumed by the redundant thrusters and to simplify the allocation of thruster forces
The omnidirectional intelligent navigator (ODIN) [9, 23] AUV is known as a near-spherical omnidirectional vehicle mounted with four horizontal thrusters and four vertical thrusters and was chosen for these numerical simulations

Summary

Introduction

Extensive efforts have been dedicated to the development of autonomous underwater vehicles (AUVs) for subsea intervention/inspection (primarily the oil and gas industries), scientific exploration, and military purposes. The excessive number of thrusters is exploited in order to improve the control performance with the thruster fault This approach resolves the thruster redundancy in the Cartesian space and allows the AUV to track the task space trajectories with asymptotic reduction of the task space errors. An adaptive region tracking control scheme is proposed for an underwater vehicle with thruster redundancy. The proposed dynamic region control scheme, where it is formulated in task space, aims to reduce the energy consumed by the redundant thrusters and to simplify the allocation of thruster forces. Unlike the conventional tracking control method, the proposed controller activates and sends commands to the functioning thrusters only when the AUV is outside the desired region and it significantly reduces energy consumption.

Kinematics and Dynamics

Fault-Tolerant Region Tracking Control Scheme

Simulation Results

Conclusion