Anti-Disturbance And Fault-Tolerant Control For Unmanned Aerial Vehicle Systems Via Disturbance Modeling

Unmanned Aerial Vehicle(UAV)has the advantages of small size,light weight,low cost,reusable and good concealment in the research of various aircraft.UAVs have been widely applied in civil and military fields.External disturbances and sudden faults widely exist in modern control systems,bringing adverse performances even causing catastrophic accidents.Therefore,the research of anti-disturbance and fault-tolerant control algorithm has been the focus in the field of control engineering.This paper regards UAV system as the research object which is subject to external disturbances and actuator faults.By constructing the disturbance observer(DO)and fault diagnosis observer(FDO),and further combining the disturbance-observer-based control(DOBC),the integral sliding mode control(ISMC),the T-S fuzzy disturbance model with the convex optimization algorithm,a series of effective anti-disturbance and fault-tolerant control algorithms are proposed.Meanwhile,the proposed control strategies can guarantee the multi-objective control requirements for the UAV system.The main contents of the paper are as follows:(1)Anti-disturbance control of UAV system based on T-S disturbance modeling is studied.The kinematics model of UAV system is discussed,and the linear equation of state of UAV system is obtained by using small perturbation linearization.The T-S fuzzy disturbance model is introduced to realize the dynamic description of irregular and external disturbances.A full-order observer is constructed to dynamically estimate unknown state of the UAV system and external disturbances.Furthermore,by combining with the estimation information,the feedback controller is designed to achieve the effective control of UAV system and compensate the matched disturbances.Based on the Lyapunov method,the UAV system can be verified to be stable under the influence of disturbances.(2)By using the integral sliding mode(ISM)method,the anti-disturbance and fault-tolerant control is proposed for the UAV system with known state.For the cases where mismatched disturbances and actuator faults occur simultaneously,the disturbance observer(DO)and fault diagnosis observer(FDO)are constructed to estimate unknown disturbances and faults dynamically.By combining the dynamic model of the UAV system and the estimated signals,an integral sliding surface(ISS)and the integral sliding mode(ISM)controller are considered,simultaneously,which realize the dynamical compensation for the actuator faults and mismatched disturbances existed in the UAV system.Furthermore,by employing the convex optimization algorithm,it can be verified that the UAV system has satisfactory stability performance and dynamic tracking performance.(3)By using the ISM method,the finite time anti-disturbance and fault-tolerant control is presented for the UAV system with unknown state.On the one hand,a composite observer is constructed to estimate the unknown state,actuator faults and mismatched disturbances timely.On the other hand,an integral sliding surface(ISS)and an ISM controller are designed to achieve effective control of the UAV system.Meanwhile,combining the finite time control method,the dynamic trajectory of the extended state can be driven to the ISS within a finite time.Based on the convex optimization algorithm,not only stability of closed-loop augmented system,but the favorable tracking performance and the output constraints can be guaranteed.(4)The above algorithms are verified by simulation,and the effective estimation of harmonic disturbance,attenuated harmonic disturbance,sawtooth wave disturbance,impulse disturbance as well as actuator faults is realized respectively,so as to ensure the multi-objective control requirements of the UAV system.