Study On Attitude Algorithm And Formation Technology For Four Rotor UAV

With the rapid development of society,the four rotor UAV has attracted more and more customers’ attention because of its advantages,so it will have broad application prospects in the future.Due to the limitation of single four rotor UAV,the cooperative formation control technology of multi four rotor UAV has attracted attention from all walks of life,and it has become a hot topic in current research.Based on the study of the attitude calculation of four rotor UAV,the cooperative formation control technology of multi four rotor UAV is studied in this paper.The main contents are as follows:Firstly,the appropriate coordinate system was used to establish the centroid model and angular motion model of a single four-rotor UAV based on the structure and force of the four rotor UAV.Then,using the dynamic model of four rotor UAV to calculate the attitude angle.Because the attitude data collected by the IMU unit will be zero drift when the four-rotor UAV is stationary,and the four rotor UAV will generate vibration noise due to the vibration of motor during flight,In this paper,the attitude angle of four rotor UAV is respectively calculated by two methods,one is combining EKF with four elements and complementary filter,the other is adaptive complementary filter combined with four elements.According to the flight test results of the four rotor UAV,the adaptive complementary filter combined the four element solution is used to calculate the attitude angle of the four rotor UAV.Thirdly,according to the result of attitude angle,the flight control algorithm of single four rotor UAV is studied.The classic PID,the adaptive integral separation PID,the cascade PID and the fuzzy PID are applied to the four rotor UAV control system respectively.According to the characteristics of four rotor UAV formation control system,an adaptive fuzzy PID controller is proposed.The control algorithm adopts segmented control,when the difference between attitude expectation and actual value of the four rotor UAV are greater than the set threshold,the fuzzy PID controller is used to control the four rotor UAV to improve the response speed of the entire control system.When the difference between the attitude expectation and the actual value of the four rotor UAV is less than the set threshold,the integral separation PID controller will be used in order to reduce the steady-state error of the system and improve the efficiency of the system.Finally,in order to realize the coordinated control of multiple four rotor UAVs,A cooperative control model of multi four rotor UAV was established according to the relationship between the relative speed and relative position coordinates of the adjacent four-rotor UAVs and the current four-rotor UAV during the formation flight of multiple four rotor UAVs.In this paper,the simultaneous construction method of line segment and super ellipse is proposed to get the formation constraint of the multi four rotor UAV.By changing the parameters of the line segment and super ellipse,different formation is described,and the formation transformation of the UAV is realized.The outer loop and inner loop PID control is realized by collecting the position error of adjacent four rotor UAV and the whole formation control system.The correctness of the formation control method is proved by Matlab simulation and real cooperative flight experiment.