A virtual thruster-based failure tolerant control scheme for underwater vehicles

This paper presents a preliminary set of results on the design of a virtual thruster-based failure tolerant control scheme for underwater vehicles. The proposed control scheme is based on the use of a suitable thruster allocation algorithm, which consists on a modified version of the Moore-Penrose pseudo inverse. When a thruster experencies a failure, the “virtual” thruster concept is introduced, as an ideal faultless thruster that operates in places of the real failed one. Thus, the resulting thrust force, which should be allocated to the failed actuator (i.e., virtual thrust), is instead reallocated to the still functional thrusters. A bank of controllers is built so that each controller is designed to control the considered underwater vehicle under a specific actuator failure scenario.