Bank of controllers and virtual thrusters for fault-tolerant control of autonomous underwater vehicles

This paper proposes a fault-tolerant control based on a virtual thruster approach for autonomous underwater vehicles (AUVs) with four horizontal and two vertical thrusters. This methodology defines that, in case of partial fault or complete fault (failure) in horizontal thrusters located in different action planes (which defines the axis or plane where component(s) of forces are actuating in this plane), horizontal propelling forces are calculated through the allocation matrix, used in the pseudo-inverse method, without any change, and a modified weighted matrix. Then, the resultant forces of the remaining working thrusters are calculated by using virtual forces. These forces correspond to the failing thruster forces projection into the forces of the remaining thrusters located in the same action plane. Additionally, we use a bank of controllers to reconfigure the controller against the fault, which improves the performance. Simulation results of a real vehicle show that this is an effective method to cope with the problem of fault tolerant control of AUVs.