Fixed-Time Control And Application For Unmanned Aerial Vehicles

Unmanned aerial vehicle(UAV)has aroused the close attention of the researchers because of its wide application.Quad-rotor UAV is also called quad-rotor aircraft,which is the simplest and most popular one of the multi rotor UAVs.It has been widely applied in aerial photography,geological exploration,pipeline inspection,environmental assessment and other fields.The research on the control of quadrotor UAV has important practical significance.Firstly,the theory,theorem basic principle of sliding mode control are introduced.According to the structure of the Four-rotor UAV system,the system dynamics model is established,and the closed-loop control system is further analyzed.This dissertation proposes a fixed-time nonsingular terminal sliding mode control methodology for Unmanned Aerial Vehicles with the presence of nonlinearity and external disturbance.A fixed-time terminal sliding surface is constructed,the controller of position subsystem,and attitude subsystem is designed.The stability of the sliding mode control of the quadrotor UAV is guaranteedand,and the settling time is independent of initial system states.Based on a new sliding surface expanded from terminal sliding mode control,a switching control method is introduced into the control law design to avoid the singularity.The proof of the global stability of the nonsingular terminal sliding mode control systems is also given in this dissertation.The Matlab simulation results verify the effectiveness of the sliding mode control method.On the basis of theoretical derivation and Matlab simulation,the fixed-time non-singular terminal sliding mode control is applied to the actual four-rotor UAV experiment to realize the recognition and tracking of the falling sphere.The image acquisition,communication accuracy and recognition accuracy are tested,and good experimental results are achieved.