Fault-Tolerant Time-Varying Elliptical Formation Control of Multiple Fixed-Wing UAVs for Cooperative Forest Fire Monitoring

This paper investigates the cooperative forest fire monitoring problem of multiple fixed-wing unmanned aerial vehicles (UAVs) in the presence of actuator faults during the fire monitoring mission. By using the fractional-order sliding-mode control strategy, a fault-tolerant time-varying elliptical formation control scheme is developed for multiple UAVs to monitor the elliptical spread of forest fire. To estimate the lumped disturbances induced by the external disturbances and actuator faults, sliding-mode disturbance observers are developed by introducing reference systems and sliding-mode differentiators. It is proved that all fixed-wing UAVs can be steered to elliptically monitor the forest fire and the cooperative tracking errors are uniformly ultimately bounded. Simulation results have demonstrated the effectiveness of the proposed control scheme.