Overall Design And Realization For A Multirotor UAV

In recent years, multi-rotor and its related products have entered people's vision, attracting wide attention of scholars and public. Compared to other novel structure, Multi-rotors have the advantage of more flexible operation and good mobility, it can take off and land vertically, hover smoothly, etc. Multi-rotor UAVs have become the focus of research in the field of unmanned aerial vehicles. In this paper, we have completed dynamic modeling work for a six-rotor, and made a key research on flight control algorithm and attitude integration, the main contents of this paper include:First of all, the system components of the multi-rotor unmanned aircraft were analyzed, and the selection of brushless DC motors, propellers, ESC, lithium batteries and the body frame were completed. Then we designed aircraft flight control circuit module including embedded microcontroller, accelerometer, gyroscope, magnetometer, barometer, GPS and wireless communication modules.Secondly, based on the analysis of the flight control theory, the dynamic model was systematically established according to the Newton-Euler method, which provided a theoretical basis for the design and implementation of the flight control algorithm. Then, the control circuit was divided into inner and outer loop. And the PID algorithm was used to control the the gestures loop(inner loop) and position loop(outer loop). Simulation results demonstrate the feasibility of the algorithm.After that, the ellipsoid fitting method, which based on the analysis of the main error source of IMU, was used to make a rapid calibration. Then, the extended Kalman filter was used to deal with the corrected data of IMU to get the data after attitude fusion. In attitude fusion algorithms, the Earth's magnetic field data didn't participate attitude fusion algorithm of the roll angle and pitch angle, which greatly increased the anti-jamming capability and safety. The algorithm was different from other attitude fusion algorithms, it was able to estimate bias of gyroscope and accelerometer any time, otherwise it adapted to the long flight.Finally, the detailed design of the embedded system software were completed. Then it was tested after being ported into the flight control board. Through continuous debugging and outdoor flight experiments, the six-rotor unmanned aircraft had the ability to accurately measure the attitude and it can ensure the stability and accuracy of flight.