Tracking Error Based Fault Tolerant Scheme for Marine Vehicles with Thruster Redundancy

TL;DR

Addresses fault tolerance for thruster-redundant marine vehicles by detecting and identifying thruster faults directly from tracking errors. The approach constructs a tracking-error residual $\bm{e}_{\eta}$ and triggers fault detection with a threshold, followed by a trend-based identification leveraging the weight estimates $\hat{\bm{W}}$. A backstepping controller ensures exponential stability for 3DOF horizontal-plane tracking, while control allocation compensates for reduced thruster outputs through weight reconfiguration. Numerical results with a BlueROV2 model demonstrate reliable fault detection and timely identification, with discussion on uncertainties and potential extensions to relax restrictive assumptions.

Abstract

This paper proposes an active model-based fault and failure tolerant control scheme for a class of marine vehicles with thruster redundancy. Unlike widely used state and parameter estimation methods, where the estimation errors are utilized to generate residual, in this paper we directly apply the trajectory tracking error terms to construct residual and detect thruster fault and failure in the steady state of the tracking system. As for identification or diagnosis, this paper proposes a novel scheme through a detailed examination of the tracking error trends and the combinations of thruster configurations. Since this fault detection and identification operates within the same closed-loop of the tracking control system, control reconfiguration can be easily achieved by adjusting the weight parameter of the isolated thruster to minimize tracking errors or residual. Numerical studies with the real world vehicle model is also carried out to verify the effectiveness of the proposed method.

Figures (10)

• Figure 1: Vehicle thruster configuration.
• Figure 2: Analysis of the relationship between tracking error change trends and thruster configuration.
• Figure 3: Reference trajectory and its tracking w/o thruster fault.
• Figure 4: Actual control input $\bm{u}$ w/o thruster fault.
• Figure 5: Residual trend in the tracking w/o thruster fault.