Research On Observer-based Reliable Control Method For A Quadrotor

Quadrotor not only has the advantages of small size,easy to carry,low cost and flexible vertical takeoff and landing,and can easily enter the dangerous environment difficult to explore,along with the processor,sensors and flight control and other related technologies are changing rapidly,it has broad market demand.However,quadrotors are susceptible to uncontrollable factors such as air resistance and motor damage when performing flight missions,making the quadrotors unable to complete their missions and even cause crashes.Therefore,in order to achieve reliable control of quadrotor when it is subject to external disturbance and fault conditions,the paper investigates disturbance rejection control(DRC)and fault tolerant control(FTC)strategy for quadrotor.The specific research contents are as follows:First,in the quadrotor system,the system performance is degraded due to system uncertainty and unknown external disturbances,i.e.,composite disturbances.A disturbance observer is designed to estimate the composite disturbance values online,and a disturbance rejection controller is designed to compensate for the composite disturbances using backstepping and terminal sliding mode technologies.The estimation performance of the proposed disturbance observer and the ability of the DRC to effectively suppress the disturbance are verified through simulation comparisons.Secondly,based on the consideration of external disturbance,an active FTC strategy is proposed for the bias fault of the actuator of the quadrotor system.In this section,an adaptive sliding mode fault observer is designed to estimate the state and bias fault value of the attitude system online.According to the information obtained by the observer,the controllers are designed in combination with integral backstepping and sliding mode control technologies.Through several sets of simulation comparisons,the accuracy of the designed observer to estimate the fault and the good fault tolerance of the fault tolerant controller are verified;Finally,in order to consider the effects of the quadrotor actuator partial failure and external unknown disturbance,an adaptive fault observer(AFO)and sliding mode fault-tolerant controller are designed to ensure the stability.In this section,an AFO is designed to estimate the efficiency loss factor online while acquiring the system status,and a fault tolerant controller is designed to compensate for the fault based on backstepping and terminal sliding mode technologies.Several simulations are carried out to verify the effectiveness of the proposed observer and FTC strategy.