Robust fault-tolerant tracking with predefined performance for underactuated surface vessels

초록

This paper investigates a robust fault-tolerant tracking (FIT) problem of uncertain underactuated surface vessels (USVs) with unknown faults in nonlinear dynamics and saturated actuators. All nonlinearities, external forces, and faults in USVs are assumed to be unknown. Compared with the existing literature, the main contribution of this paper is to present a predefined performance design methodology for FIT of USVs that are nonholonomic systems. The predefined performance bounds, which characterize the convergence rate, maximum overshoot, and steady-state response of control errors, are integrated with error surfaces in consideration of underactuated constraints. A new FIT control scheme using the integrated error surfaces is designed without applying any function approximators to estimate unknown nonlinearities including faults and requiring the repeated differentiation of virtual controllers where auxiliary variables are derived to ensure the predefined performance of underactuated systems. Thus, compared with the previous controllers for USVs, a simple controller design can be derived regardless of unknown nonlinearities, their faults, and actuator faults. It is shown that tracking errors are preserved within bounds guaranteeing predefined transient and steady-state performance. (C) 2016 Elsevier Ltd. All rights reserved.

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