Study And Design Of Attitude Control Systems For The UAV

Quadrotor unmanned aircraft is a novel VTOL structure UAV(Vertical Take-Off and Landing UAV,VTOL UAV).Compared with fixed-wing UAV,quadrotor has a good performance in hover sentinel low flying,indoor flying task that other fixed-wing UAV impossibly completed.Compared with traditional helicopters,quadrotor has less gyroscopic effect,simple mechanical structure,easier control law.Because all of this,recent years,quadrotor has attracted its widespread attention.The quadrotor UAV has great application prospects in the field of the military and civilian because it can achieve fixed point hovering,vertical take-off and landing and indoor flight tasks.In recent years,it has become the focus of research at home and abroad.Based on the existing technology,some research about the quadrotor's mathematical model and the attitude control problem is proceeding on a homemade quadrotor platform.The attitude controller is designed according to the theory of sliding-mode variable structure control theory.The main work is as follows:First of all,this paper studies the working principle and the mathematical model of the quadrotor UAV and analyzes movement processes of attitude changing.At the same time,the attitude is described with quaternion method,and the model of vehicle dynamics is established.Secondly,the controller of quadrotor attitude is designed.On the base of the simplified system model,attitude controller based the sliding-mode variable structure control theory is designed.And the chatting phenomenon are analyzed,three improved methods are developed,which are exponent reaching law solution,variable boundary layer solution,the nonsingular terminal sliding mode control method and the second-order sliding mode control method.It is analyzed and improved by simulation results from MATLAB.Then,homemade quadrotor platform is set up.Some research about the composition of the system,components selection and control of brushless dc motor is done on the Master control system,the aircraft attitude information acquisition system,motor drive system and wireless communication system.Finally,based on the homemade quadrotor,the experiments of the control schemes proposed in this paper are implemented to validate the control effect.The experimental results show that the attitude controller designed in this paper can track expectations fast and stably,which has reached the design requirements.