The Research of Four Rotor Aircraft based on STM32

Four rotor aircraft has been extensively studied in recent years. Especially the small Four-rotor aircraft has a very broad application prospects in real life, many companies and scientific research institutions are studying. The technology involved in the Four-rotor aircraft includes flight dynamics, mechanical structure, navigation, automatic control, circuit design and so on. By developing a Four-rotor aircraft, we can not only learn a variety of knowledge and technology, but also broaden our horizons and understand the development of the current automatic control system in the process of production, which will be of great help to future work and learning.The hardware design of the Four-rotor aircraft studied in this paper includes: using STM32 series MCU as the main controller, 6-axis attitude sensor MPU6050 to collect the acceleration and angular velocity of the vehicle, electronic compass HMC5883L, to collect magnetic field, USB serial port chip CP2104, TP4056 to provide 4.2V lithium batteries. The charging voltage and charging current can be controlled, and the internal universal timer interface is used to realize the capture function of remote control input PWM waveform and the output PWM waveform to control the speed of the motor. The software design in this paper includes the configuration of serial communication, the connection between the flight control board and the host computer, the reading of sensor data, the calculation of the current attitude by the strapdown navigation control method, the output of Euler angle, the configuration of timer to achieve the function of input capture and PWM waveform output, and the application of digital PID. The controller calculates the deviation between the desired attitude input by the remote controller and the current attitude of the aircraft, calculates the duty cycle of the output PWM waveform, and adjusts the rotation rate of the four rotors to realize the six-degree-of-freedom flight state of the Four-rotor aircraft.