Research On The Fault Tolerant Control Method Of The Quad-rotor Under The Actuator Faults

The quad-rotor is a kind of multi-rotors,it has small size,light weight,low power consumption,and can realize hovering control etc.Compared with the traditional helicopters,it has relatively simple mechanical structure,therefore it has been widely used.By controlling the speed of the quad-rotor,the attitude and position of the quad-rotor can be realized.However,the quad-rotor itself is an under-actuated system,with many variables,strong coupling,nonlinear and vulnerable to external disturbances,and its position and attitude are strongly coupled.In the flight process,because of the high-speed rotary of the actuator,makes it increases the probability of failure.In order to realize the fault-tolerant control of the actuator,this paper studies the height and attitude control of the four rotors,the following work was done:First of all,expounded the research background and significance of the project,and introduced the relevant concepts of the fault-tolerant control of flight control system,next introduced the domestic and foreign research status of the quad-rotor,and finally expatiated the main work and chapter arrangement of this paper.Secondly,a brief introduction to the quad-rotor structure and work principle was done,the ground reference frame system and the body coordinate system were defined,and based on this,the gyroscopic effects and aerodynamics frictions were considered,by using the Newton-Euler formula,a particular quad-rotor dynamic mathematical model was established.According to the mathematic model,the simulation model of the quad-rotor was built in the Matlab/Simulink environment.Then,the principle of the controller design based on back-stepping method is introduced briefly,and based on the dynamic mathematical model of the quad-rotor,the actuator additive and multiplicative faults models of altitude and attitude were established,and adopted the adaptive back-stepping control algorithm,the adaptive back-stepping fault-tolerant controllers were designed amply,under the condition of failure,the fixed high hovering simulation experiment and robustness test were done.The experimental results showed that the adaptive back-stepping fault tolerant controller was feasible and effective,but its rejection to disturbance needs further improvement.Finally,the actuator failure of additive and multiplicative were both regarded as a kind of uncertainty,and considering that the faults system was affected by outside interference during the actual flight,based on the adaptive back-stepping sliding mode control algorithm,the sliding mode item was introduced in the algorithm,the altitude and attitude fault-tolerant controllers were designed,the experimental results showed that the algorithm effectively restrained the influence of external disturbances and uncertainty of the system.Two simulation experiments were carried out: The first part was the simulation experiment of fixed high hover,there was no interference in the faults model,and the other part was the anti-interference verification experiment and there was interference.And the simulation results showed that the adaptive back-stepping sliding mode control algorithm had strong robustness to external disturbances and actuator faults.Finally,two control algorithms were compared and analyzed.