Control Algorithms And Experiments Of A Micro Quadrotor

Quadrotor is a vertical take-off and landing(VTOL)aircraft,which can complete all kinds of missions just by changing the rotational speed of each rotor.These features bring it great application value in both military field and other fields.However,many problems and challenges are still in the way due to the under-actuated,strong coupling,nonlinear and multivariable characteristics of quadrotor.In this thesis,the model of a quadrotor made by German Mikrokopter Corporation is established and then a controller based on sliding mode control algorithm is designed.Besides,flight experiments are done on the experiment platform.Firstly,based on Newton-Euler equation,dynamic model of the quadrotor is established,which contains linear motion equation and angular motion equation.In view of underactuation of the quadrotor aircraft,the model is divided into full drive subsystem and under-actuated subsystem in order to simplify the system analysis and controller design.Secondly,sliding mode controllers for the model is designed.In order to decouple the system,a fast terminal sliding mode controller for full drive subsystem is designed so that the state variables of the subsystem converge to equilibrium point in a short time.By doing so,relevant state variables can be seen as constants during the analysis of the under-actuated subsystem,so that the system realizes decoupling to a certain degree and is easier to be analyzed.Furthermore,a controller through integral sliding mode control method is designed for another subsystem,whose stability is proved with Lyapunov theory.The simulation results show that,under the effect of controllers designed,the quadrotor aircraft is able to complete various tasks,including stable hover,pitch,roll and yaw and trajectory tracking.Thirdly,the hardware and software system are designed and some experiments are done.For the hardware system,the main work is analyzing and designing the circuit modules of attitude control layer.Besides,in order to verify the rationality of the sensor circuit,some simulation analysis is made with the tool of Multisim.As for the software part,the programs of the attitude control board and the motor drive layer are designed.Then,flight experiments are conducted outside,before which the parameters of flight controller have to be set on PC and the midpoint of attitude sensors should be calibrated by remote control.Finally,conclusions are presented and some open problems are also pointed out,which deserve further study.