Finite-time Fault-Tolerant Time-Varying Elliptical Formation Control of Heterogeneous Multi-agent System for Collaborative Wildfire Monitoring

Combating wildfires is an inherently perilous occupation, presenting firefighters with numerous risks. One critical responsibility of firefighters is to monitor the progression of fire borders and identify areas prone to further spread. Insufficient understanding of fire spread often results in accidents. The utilization of an air-ground heterogeneous multiple agent system (HMAS), comprising Uncrewed Aerial Vehicles (UAVs) and Uncrewed Ground Vehicles (UGVs), for wildfire surveillance holds immense potential as it can replace humans in hazardous fire tracking tasks, leading to a significant reduction in operational expenses. In this article, we propose a finite-time fault-tolerant elliptical formation control algorithm for an air-ground HMAS, assigned to collaboratively monitor the spreading of wildfires in an elliptical pattern. During the fire monitoring mission, the HMAS encounters communication link and actuator faults. The control algorithm incorporates a High-Order Super-Twist Observer (HOSTO) to estimate the multi-source disturbances, including actuator faults and external disturbances, as well as the Nonlinear Fractional-Order Terminal Sliding Mode (NFTSM) method, featuring a novel sliding surface with an exponential variable. The proposed control algorithm ensures that all agents actively monitor the elliptical wildfire, and the cooperative tracking error converges to zero within a finite time. Comparative simulation results are presented to illustrate the effectiveness of the proposed control scheme.