Research On Actuator Fault Tolerant Control Of Quadrotor Flight Control Systems

In this paper, different fault types are analyzed based on the attitude model of quadrotor inhovering mode. Based on the regional stability and Linear Matrix Inequality toolkit, different types offault tolerant controllers are designed to ensure that the quadrotor can track the desired commands andkeep a certain performance. And the methods are examined on the QstudioRP platform to verify thefeasibility and validity of the methods.Firstly, the concept of fault, the background of fault tolerant control and the meaning of researchare surveyed. Then the dynamic model of quadrotor is built and simplified to obtain the state equationof attitude. And the semi-physical platform——QstudioRP is introduced. The open loop characteristicand closed loop characteristic of the system are analyzed to provide a basis for the fault tolerantalgorithm in next chapters.Secondly, in case of voltage damage of actuators, a state feedback controller based on regionalstability is designed to configure the poles of the system to specified area to maintain D stability andH∞performance. Digital simulation and real time simulation are both run in the QstudioRP platform,and the results show good performance of the controller compared with the LQR method.Thirdly, as the uncertainty and overdrive speciality of the quadrotor model, a robust controlallocation method is proposed to deal with the voltage damage failures and stuck failures of actuators.The allocation controller and the adaptive fault tolerant control law are designed separately andfailures are compensated by adding adaptive law to achieve the advantage of good rapidity and easyengineering implementation. By abundant simulations, the size of model uncertainty measurement isreceived. With reasonable parameters, the method is simulated on the QstudioRP platform in digitalsimulation and real time simulation and show good performance compared with the LQR controllerand standard controller.Finally, because of the actuator saturation characteristics, the system may reach saturationboundary and lead to bad performances of the system when faults happen. By introducing auxiliarymatrix, the actuator saturation nonlinear term is linearized. Using elliptic invariant set to close toattraction domain, the system is stable according to series of LMIs. Also the controller is examined onthe QstudioRP platform to verify the feasibility and validity.