Design And Test Of L-F Multi-Rotor UAV Formation Cooperative Control System

Unmanned aerial vehicle(UAV)for plant protection has the characteristics of high efficiency,good quality,wide adaptability,low cost and strong ability to deal with unexpected disasters,which is receiving more and more attention from all walks of life.But at present,there are some problems in plant protection UAV,such as less payload,short idle time,etc.When a single plant is operated,it must be equipped with a special person to control,change dressing and charge batteries,which has a great impact on the improvement of operation efficiency and energy utilization rate.It is one of the important factors restricting the rapid development of plant protection UAV.The cooperative operation of multi-UAV formation is an effective way to improve the above-mentioned problems.This topic intends to design a master-slave(L-F,Leader-Follower)UAV formation cooperative control system to improve the operational efficiency of single sortie of plant protection UAV through multiUAV cooperation,which has certain practical application value.Based on the research and analysis of the development status of multi-UAV formation cooperative control system at home and abroad,this paper builds a L-F multi-rotor UAV formation cooperative control system,and designs two kinds of formation cooperative control algorithms: GNSS-CMC(Global Navigation Satellite System Coordination Mi Conversion)based on multi-source information fusion(MSIF).)The formation cooperative control compensation algorithm and GNSS-CMC formation cooperative control algorithm based on AC-TDC(Adaptive Control and Time Delay Compensation)are compared and tested.The main research work and results are as follows:(1)Two types of UAV,three-blade paddle(Butterfly-type UAV)and two-blade paddle(S500 type),were built independently.Two-blade paddles were selected as the experimental model of UAV formation cooperative control.The maximum load of a single UAV can reach 2 kg and the longest endurance can reach 25 min.On this basis,PIXHAWK open source flight control system was adopted as the core component.Based on u ORB,a new topic suitable for formation cooperative control is designed to realize multi-process asynchronous communication among modules in flight control system,and a Mesh grid network based on XBee is constructed to realize multi-UAV ad hoc network communication,which can minimize packet loss rate when disturbed.In the communication protocol,the software of formation cooperative ground control station based on Windows operating system is designed with C# language,which realizes the cooperative control of one ground station to multiple UAVs.The Commander and Navigator modules of flight control stack in PX4 firmware are reconstructed,and the overall design scheme of software and hardware of L-F multi-rotor UAV formation cooperative control system is determined.(2)Using L-F formation control method based on distributed control strategy,a GNSS coordinate system migration conversion formula for L-F formation is constructed,and a multi-source information fusion(MSIF)formation cooperative control algorithm based on position coordinates,heading angle and velocity is designed.The formation flight test of the algorithm is carried out using S500 Four-rotor UAV.In the experiment,one leader and two followers were set up to fly in formation.The experimental results show that the mean square root error of the average distance tracked by the wingman is 3.123 m and the maximum deviation is 4.535 M.The maximum delay time followed by the speed of the wingman is 4.700 s,the minimum delay time is 3.000 s and the average delay time is 3.775 s.(3)Aiming at the problems of low formation control accuracy and slow signal response rate in formation flight,a GNSS-CMC formation cooperative control algorithm based on adaptive control and time delay compensation is proposed on the basis of MSIF algorithm.The formation flight test of the algorithm is carried out using S500 Four-rotor UAV.。 In the experiment,one L and two F are set up to fly in formation.The results show that the mean square root error of the average distance tracked by the wingman is 0.70750981 m and the maximum deviation is 0.849719073 cm.The maximum delay time of the speed following of the wingman is 0.7s,the minimum delay time is 0.4s and the average delay time is 0.525 s.The control accuracy of formation flying and the response rate of UAV to command signal are greatly improved.