Design And Implementation Of The Four Rotor Aircraft Based On The STM32

Four rotor aircraft is one of the unmanned spacecraft,and by changing propeller pitch angle so as to control the attitude and position compared to the traditional helicopters,it has the following advantages: small volume,flexible,good concealment,vertical take-off and landing,a certain capacity,user control performance is strong,etc,it is suitable for the aerial photography,low-altitude reconnaissance,communication relay,agricultural plant protection,monitoring and investigation,widely used in military and civil fields.Four rotor aircraft with four control input and six state output belongs to the underactuated system,is not easy to control.Based on the analysis of rotor type of unmanned aircraft flying principle and according to the control system function demand,research on the controller application corresponding inertial navigation theory to solving flight attitude,and application of control theory to realize stable flight control of aircraft.In this paper,according to the characteristics of the physical structure of the four rotor craft and the calculation principle of the airborne attitude data and the attitude angle control method,designed to carry Cortex-M3 processor core STM32 series microcontrollers as the core,MPU9250 inertial measurement unit for the flight control system.The controller calculates the current flight motion pose by the real-time measurement data of the attitude sensor and combines the analyzed wireless remote control signal data to calculate the adjustment amount of the four brushless motors to control the rotation number of the four rotors respectively,to achieve the final adjustment of the aircraft motion posture.For the problem that the attitude sensor unit is susceptible to interference,there is integration divergence and temperature drift,and the original data is collected for the complementary filter to ensure the accuracy of the data fusion.Combined with the characteristics of micro-controller,the attitude update using a quaternion algorithm to reduce the controller to do cosine operation time to ensure the body attitude control requirements of real-time.The fuzzy PID controller is used to improve the attitude angle control,the fuzzy inference and the PID control strategy are complementary and independent of the system precise model,and the control is fast and flexible.Finally,the function modules in the system are debugged and the attitude control and the steady flight of the aircraft model are successfully completed under the laboratory conditions.The rationality of the design scheme of the four rotor aircraft control system is verified through experiments.