Fault-Tolerant Cooperative Control Of The Multi-Unmanned Ground Vehicles System

As multi-unmanned ground vehicles are increasingly applied in real-world scenarios,there is worldwide attention on their development.Because of the great development of communication technology and artificial intelligence,study about multi-unmanned-ground-vehicles formation control has been drawn significant attention,recently.Considering that once an actuator fault occurs in one of the vehicles in a multi-unmanned ground vehicle system during practical applications,it may cause instability in the entire system and possibly lead to mission failure.Therefore,analyzing and discussing actuator faults during the formation of multi-unmanned ground vehicles is of great engineering significance.Overall,unmanned vehicle actuator faults can be classified into two types: partially lost faults and severe faults.Partially lost faults occur when the fault value is within a certain range,while severe faults occur when the fault value exceeds this range.This paper will propose different control schemes based on the severity of the fault to achieve effective formation control.The main context is described as follows:For partially lost faults,this article proposes a fault-tolerant formation control strategy.First,the wheeled mobile unmanned vehicle with actuator faults are modeled,and a state transformation method is introduced based on the vehicle model to facilitate the design of the formation control.Two fault estimation methods are then proposed: the adaptive fault factor estimation method and the observer fault factor estimation method.These methods are used to monitor the actuator fault status,and a distributed consensus fault-tolerant formation controller based on fault estimation compensation is designed under the leader-follower framework.The stability of the controller is proven using Lyapunov analysis.Finally,the formation controller parameters are optimized and tuned using the sparrow search algorithm to further improve the convergence speed of the formation control.Simulation tests with seven unmanned ground vehicles show the effectiveness of the proposed fault-tolerant formation controller.For severe actuator faults,this article proposes a fault-tolerant control strategy based on formation reconfiguration.Once a severe fault in one of the unmanned vehicles’ actuators occurs that prevents it from functioning properly,the faulty vehicle is removed from the formation,and the remaining healthy unmanned vehicles reconfigure a new formation to complete the task.The proposed method firstly uses the Hungarian algorithm to reassign the positions of each unmanned vehicle in the new formation and uses the Grey Wolf Optimization-Whale Optimization Algorithm to plan the path for each unmanned vehicle to reach its new position in the formation.Then,a new formation controller is designed and its stability is analyzed.It should be noted that the proposed controller consists of three parts:(1)a consensus-based distributed formation controller,which aims to control the remaining unmanned vehicles to maintain the expected formation;(2)a potential-based collision avoidance controller,which aims to avoid collisions between vehicles during the process of forming the expected formation;(3)a PI-based path tracking controller,which aims to ensure that the unmanned vehicles can reach the expected formation position along the pre-planned path.The three-part controller for formation reconfiguration tasks works together to ensure that unmanned vehicles can reach the position as required and maintain the reconfiguration formation.The effectiveness of the reconfiguration formation control method is verified through a simulation example.