Study And Design Of Flight Control System For Quadrotor UAV

Quadrotor UAV has a simple structure and flexible flight,so it has been widely attended in recent years.But the flight control system has four inputs and six outputs of DOF,so the system is a typical underactuated,nonlinear and strong coupling system,which makes it so complex and difficult to control UAV.This paper aims to design a complete flight control system by studying the flight control technology.The main contents are as follows:Firstly,after introducing the flight principle of the quadrotor,this paper establishes the relevant coordinates and deduces the dynamics model of the quadrotor by physics.Then the model is linearized and decoupled,and is divided into horizontal channel,longitudinal channel,vertical channel and yaw channel.Horizontal and longitudinal channels control position in the outer loop,and control attitude in the inner loop;yaw channel controls yaw angle;the vertical channel controls height.While building motor model,and finally get the transfer function of the four channels.According to the characteristics of each channel,this paper designs the different algorithms controller.For linear motion is relatively simple,the horizontal channel and the longitudinal channel control the position by PID,and the model of Quadrotor changes easily,coupled severe and susceptible to be interference,and the traditional double-loop PID control posture unable to meet its robustness,so control the attitude angle by H_?.For the yaw angel substantially unchanged,the yaw channel controls the yaw angle by LQ.For the height is controlled easily,the vertical channel controls height by PID.The design not only improves the robustness and the capability of interference suppression of the system,but also makes the energy used best.Then the fixed-point flight of the quadrotor is simulated in MATLAB,and this paper analyzes the AHRS curve of the simulation,and proves the feasibility of Sub-channel control by decoupling.Then it analyzes controlling effect on each channel,and proves that the proposed control strategy is effective.Subsequently,this paper builts the hardware platform,and elaborates the equipment selection and circuit design of the main modules,including sensor module,wireless transmission module,main control chip and power supply module.Then based on FreeRTOS operating system,the software is designed,and achieves implements sensor task,remote control task,PC interactive task,solving task and flight attitude control task.The flight attitude control task implement control algorithms in the real platform,and each module of the flight control system can work normal and orderly.Finally,a test of fixed point flight is carried out,and comparative analysis of the effects of flying controled by the traditional double-loop PID and H_?.So it proves that the proposed control strategy is effective,and the flight control system has high stability and a certain degree of interference suppression.