The Implementation Of Flight Control Unit For Agricultural Multi-rotors UAV

With the development of society,the unmanned aerial vehicle(UAV)with multi-rotor is used in agricultural plant protection gradually occupies the markets and the applications on which are promoted continually.The research object of this paper is the flight control system of the UAV with multi-rotor used on agricultural plant protection.The unmanned aerial vehicle with four-rotor and the open source about flight control system are used as the base platform of this research.According to the problems such as obstacle avoidance during spraying pesticide,extended to the functional defects existing in flight control system.The solutions are developed through the analysis and the functions of flight control system are designed and improved to make application turn better.Firstly,this paper introduces the hardware system of UAV,and then analyzes compositions and functions of the flight control system module,sensor module,wireless transmission module and power module.Based on the analysis above,this paper compares and analyzes the product components of each module in the UAV selected.The appropriate product devices are selected by performance according to the performance parameters.Secondly,the thesis analyzes the famous open source code PIXHAWK about flight control at the current situation and focuses on the analysis of the main function modules which lay the foundation for the next step of algorithm design,program debugging and completing the flight control system function.Further more,based on the analysis on the principle of flight control in the UAV with multi-rotor,the control process of PID is described in detail according to the control directions of the unmanned aerial vehicle(UAV)selected with four-rotor in this thesis.The correlation coefficient is confirmed by experiments.Then,we focus on the obstacle avoidance defect in the UAV used on plant protection.According to the specific demands for UAV used in agricultural plant protection,a analysis on comparison of the existing technologies on the ultrasonic obstacle avoidance,TOF obstacle avoidance and machine vision obstacle in robots and automatic cars is made to determine a better scheme.Then obstacle avoidance algorithm is designed in detail to further strengthen the function of flight control system.Finally,a flight test is carried out on the assembled UAV with four-rotor by means of on-board simulation test and field flight test.This paper completes the design of the obstacle avoidance module in flight control system,and verifies the feasibility of the obstacle avoidance scheme...