Research On Estimate And Control System For The Attitude Of Quad-rotor

With the rapid development of aviation technology and microelectronics technology,the researches of the unmanned aerial vehicle(UAV)become popular,especially the rotor aircraft,with its peculiar advantage,become the focus of attention at present.In order to adapt to the use of different areas,there are many kinds of new type,which has the function of vertical take-off and landing unmanned aerial vehicles,Quad-rotor is currently the most watched wing aircraft.Through cross structure,forms the symmetry of body structure,four BLDC motor installed at the top of the cross structure of motors,and through the propeller of the positive and negative,provide symmetric torsion,offset the torque force,only need through feedback,control the motor speed,stable flight can be realized.Quad-rotor autonomous flight generally adopt double loop control,the outer loop control the trajectory,the inner loop control the attitude.The outer loop flight path stability of inner loop control for autonomous control provides the necessary conditions.This article main research inner loop control for aircraft,namely attitude of decoding and control research.In this paper,the research platform of aircraft and ground monitoring and control system for autonomous design.Aircraft use STM32 as controller,using the gyroscope,accelerometer and magnetic sensor,aircraft attitude information feedback,by comparing the control system of a given posture,to correction of spacecraft attitude continuously,so as to realize the stability of inner loop control.Quad-rotor model is complex,it is not easy to build accurate model.This paper has established the four rotor aircraft dynamic model and operation model.Because the motor is a nonlinear,and the propeller model more complex,so when the propeller model of motor,the method of interval model was adopted,in a certain range,measure the speed of the motor-propeller,and then read the corresponding tension,and through MATLAB,using the least square method,to speed-lift curve fitting.Finally,the part of the model is simplified,so that in the simulation,the lower order and reduce computational complexity.Before the aircraft attitude algorithm,first the gyroscope,accelerometer and magnetic sensor calibration.In the process of correction,gyroscope using measuring average worth zero drift method obtained for many times,the accelerometer is calculate by the method of vector translation zero drift.Magnetic sensor is difficult getting zero drift,based on the conventional ellipsoid fitting method,obtain the magnetic zero drift.Vector rotation and interpolation and gradient descent of the two kinds of solving methods areintroduced and compared,through comparison,at the time of rotation vector interpolation tocalculate attitude,its advantage is small computational complexity,but slightly less accuracy,gradient descent is used to measure the attitude,its precision is better,but the computational cost is larger,under different engineering need,can choose the appropriate algorithm according to conditions.Due to the symmetry,electrical installation,for calculation of yaw Angle caused the larger error,so you need to use the kalman filter,the yaw Angle profile.In the attitude control,to improve the traditional PID controller,increased the front kalman filter.Through this design,can better to gesture to realize fast and stable control.In this paper,we use based on the frequency domain response of Ziegler-Nichols PID setting method,to determine the value of PID.The system's overall program design are introduced int the end of the article.In this paper,the various functions of the software process are designed by the meaning of modular programming.