PTNDO-based distributed active fault-tolerant control for leader–follower vehicular formation with unknown direction faults

This paper investigates the problem of distributed predefined-time active fault-tolerant control for vehicular formation systems subject to unknown direction actuator faults, unknown nonlinear dynamics, and external disturbances. First, two novel predefined-time stability lemmas are proposed, eliminating the need for quadratic fractional functions or piecewise continuous functions, thereby avoiding singularity issues. Subsequently, a novel predefined-time nonlinear disturbance observer (PTNDO) is designed to accurately estimate the lumped disturbance within a predefined time. It is worth mentioning that, based on the proposed PTNDO, a novel reverse fault detector (RFD) by utilizing the disturbance estimation error is developed to accurately detect the reverse faults, and then a predefined-time active fault-tolerant strategy is constructed to avoid the control input peaks and excessive control gains caused by existing Nussbaum function-based methods. Furthermore, the proposed fault-tolerant control strategy not only ensures that the formation error converges to a neighborhood near the origin within a predefined time but also maintains inter-vehicle communication connectivity and collision avoidance. Finally, simulation experiments demonstrate the effectiveness and superiority of the proposed control strategy.