Research On Attitude And Altitude Control Method Of Quad-rotor Aircraft

Quad-rotor aircraft has a series of advantages such as simple design structure,flexible flight and low maintenance cost.So far,it has been widely used in civil and military fields,such as line inspection,fast logistics,personnel search and rescue,target tracking,etc.,which are very important Research significance and value.The Quad-rotor aircraft is a nonlinear system with strong coupling and under-drive.Its controller design has certain difficulties,especially the controller design under fault conditions.This dissertation takes Quad-rotor aircraft as the research object to study the altitude and attitude control of Quad-rotor aircraft,as well as the fault-tolerant control of Quad-rotor aircraft by redefining the internal state of the system and designing control algorithms when actuator failure occurs during flight.First of all,after consulting a large number of relevant documents,based on the structural characteristics and flight principles of the Quad-rotor aircraft,a nonlinear rigid body dynamics model of the Quad-rotor aircraft was established by the Newton-Euler method,Through the relationship between rotor speed and force and torque,the control efficiency model of the Quad-rotor aircraft is derived,which lays the foundation for the subsequent simulation experiments.Secondly,in order to improve the robustness and anti-interference performance of the Quad-rotor aircraft during flight,a back-step sliding mode attitude control method is designed to divide the whole system into the idea of back-stepping in order to improve the robustness and anti-interference of the system.In the two parts of position control and attitude control,the back-step sliding mode control law is designed respectively.Considering that the Quad-rotor aircraft is susceptible to interference,disturbance observer and adaptive control are added to improve the anti-interference ability of the control system.The simulation results show that this control method can make the attitude channel of the Quad-rotor aircraft reach the desired value quickly,and it can return to the stable state under the condition of disturbance.Then,the problem of attitude tracking of the Quad-rotor aircraft is solved when the model and parameters of the Quad-rotor aircraft are uncertain.Through incremental nonlinear dynamic inversion,the position and attitude control of the Quad-rotor aircraft is completed.This control method simplifies the gain setting and provides good robustness to large aerodynamic disturbances during flight.It can be seen from the experimental results that the four-rotor aircraft can track the set reference value in a short time.Finally,according to the type of failure,it is divided into single-actuator failure and double-actuator failure.In the event of a fault,actively abandon the control of the yaw axis to improve the control effect of the other two attitude angles,and reduce the dependence of the incremental nonlinear dynamic inverse on the Quad-rotor aircraft model through the sensor,and reduce the error.Through the simulation experiment of the above-mentioned fault-tolerant strategy,it can be seen that the fault-tolerant controller designed in this paper has a good fault-tolerant fault control effect.Finally,a systematic summary of the research content of this article is made,and the shortcomings of the current research content are pointed out,and a simple reference is made to the follow-up research direction and research content.