Prescribed Performance Finite-time Tracking Control For A Quadrotor UAV With Unknown Initial Tracking Condition

Quadcopter unmanned aerial vehicles(UAVs)play an irreplaceable role in many places that people can not touch because of its small body and strong flexibility.Due to the characteristics of nonlinearity and strong coupling,and are easily affected by air resistance and external interference,the research on resist interference of quadcopter UAVs has become a research hotspot.In addition,the failure of the actuator mechanism composed of the motor and rotor of the quadrotor UAV can make the flight mission impossible to complete,causing damage to the airframe and even threatening the safety of life and property.In order to ensure the safety and reliability of the quadrotor UAV during flying,it is necessary to study its fault-tolerant control to ensure the stable operation of the system.In this thesis,the research contents for the quadrotor UAV system of this thesis are as follows:Firstly,the research background and significance of quadcopter UAV are expounded,and the current control research of UAV system is summarized,and the nonlinear dynamic model of quadrotor UAV system is established according to the flight principle and rigid body structure of the quadcopter UAV.Secondly,the active disturbance rejection prescribed performance finite-time tracking control problem is studied for a quadrotor UAV system with unknown initial tracking condition and external interference.By using a prescribed performance control design method without dependence on initial tracking conditions,the problem to design prescribed performance controller of the UAV system with unknown initial tracking condition is solved.This method provides a new idea for the application of the prescribed performance control design method in practice.Based on this new prescribed performance control method,an active disturbance rejection prescribed performance finite-time tracking controller is obtained by combining backstepping method,active disturbance rejection technology and finite-time control.The designed controller can ensure that the tracking error of the quadrotor UAV system can be constrained by prescribed performance function,all the signals in the system are bounded,and the system has a good suppression effect on external disturbances.The simulation study verifies the effectiveness of the control algorithm.Finally,an adaptive prescribed performance finite-time H∞ tracking control problem is studied for a quadrotor UAV system with actuator failure and unknown initial tracking condition.By using a prescribed performance control design method without dependence on initial tracking conditions,the problem to design prescribed performance controller of the UAV system with actuator failure and unknown initial tracking condition is solved.Based on this control method,an adaptive prescribed performance finite-time H∞ tracking controller is obtained by combining fault-tolerant control,prescribed performance control,finite-time control and bounded H∞ control in the design process.The designed controller can guarantee the transient,steady and anti-interference performance of the quadrotor UAV system at the same time.The simulation results show the effectiveness and superiority of the proposed control method.