Research On Attitude Measurement And Control Algorithms Of Four-rotor UAV Based On Embedded System

Compared with ordinary aircraft,quadruple-rotor UAV has simple structure and is often used in various missions.It has a very broad application prospect.Therefore,it has become a research hotspot at home and abroad.The attitude measurement system and control system of Four-rotor UAV are the most important parts.The attitude measurement system measures the attitude of the Four-rotor UAV at all times,and inputs the calculated attitude information into the control system.And the control system will send instructions to the follow-up executing agencies to enable the UAV to fly in accordance with the specified trajectory without external interference,according to the comparison between the current attitude information and the target trajectory.The attitude measurement and control system of UAV directly determines the flight performance of UAV.At the same time,the research of attitude measurement and control system of UAV involves many fields such as electronics,communication,automation,computer and so on.It has considerable frontier in technology.In this paper,a measurement and control system for autonomous flight of Four-rotor UAV is designed based on embedded system.The mathematical models of the Four-rotor UAV and its motor are obtained,based on the analysis of the Four-rotor UAV and its motor.And The corresponding simplification is carried out to provide the state equation of the system for the design of the controller.According to the state equation of the Four-rotor UAV,tracking the target trajectory and the current attitude and position information of the Four-rotor UAV,several controllers are designed and simulated by Matlab.By comparing their tracking performance,anti-jamming performance and robustness performance,it is proved that the control algorithm combining fuzzy controller and sliding mode controller has better control performance.Its response time can be controlled within 1s,and there is almost no overshoot.It can respond quickly when disturbed by outside or system parameters change.In order to get the accurate navigation information needed by the controller,the digital filter is studied.By comparing the Kalman filter with the complementary filter,the Kalman filter has better filtering performance in the navigation system.The Kalman filter is designed for the Four-rotor UAV system.According to the actual situation of the Four-rotor UAV,the Kalman filter is designed by using Verilog language on CPLD through the combination of indirect method and direct method.In order to realize the autonomous flight of the Four-rotor UAV,the corresponding navigationsensors are selected and ARM is used as the main control chip of the system,thus the control signals of the Four-rotor four motors are obtained.According to the requirements,the experiment system is designed and completed,including the design of hardware circuit and the compilation of upper and lower computer software.The stability and feasibility of the system are verified by flight experiments.