# Hierarchical Fuzzy Adaptive Observer-Based Fault-Tolerant Consensus Tracking for High-Order Nonlinear Multi-Agent Systems Under Actuator and Sensor Faults

## TL;DR

This paper presents a new control method for multi-agent systems to maintain coordination despite sensor and actuator faults and disturbances.

## Contribution

A hierarchical fuzzy adaptive observer-based fault-tolerant control framework is proposed for high-order nonlinear multi-agent systems.

## Key findings

- A distributed output predictor prevents fault propagation and estimates the leader's trajectory.
- The controller ensures tracking error converges to a small neighborhood of the origin.
- Simulations confirm the method's robustness to multiple simultaneous faults and disturbances.

## Abstract

This paper investigates the consensus tracking problem for a class of high-order nonlinear multi-agent systems subject to actuator faults, sensor faults, unknown disturbances, and model uncertainties. To effectively address this problem, a hierarchical fault-tolerant control framework with fuzzy adaptive mechanisms is proposed. First, a distributed output predictor based on a finite-time differentiator is constructed for each follower to estimate the leader’s output trajectory and to prevent fault propagation across the network. Second, a novel state and actuator-fault observer is designed to reconstruct unmeasured states and detect actuator faults in real time. Third, a sensor-fault compensation strategy is integrated into a backstepping procedure, resulting in a fuzzy adaptive consensus-tracking controller. This controller guarantees the uniform boundedness of all closed-loop signals and ensures that the tracking error converges to a small neighborhood of the origin. Finally, numerical simulations validate the effectiveness and robustness of the proposed method in the presence of multiple simultaneous faults and disturbances.