Research Of Control And Calculation Of Position-Attitude For Four-rotor Mini Rotorcraft

Four-rotor mini rotorcraft with its high stealth and flexibility adapts to work in harsh environments.So it has a high value of application.The quadrotor is a nonlinear and underactuated system that greatly increases the difficulty of control.Therefore,This paper focuses on the position attitude information solution and research of control algorithm for four-rotor mini rotorcraft.The purpose is to make the rotorcraft flight more stable,stronger in anti-interference and more practical.the movement principle of the four-rotor mini rotorcraft in the air and the conversion between the two coordinate systems are analyzed in detail.Moreover,the hardware platform of the flight control system and ground control station was designed.Based on the hardware platform,the position attitude information of the four-rotor mini rotorcraft is resolved.The position attitude information includes attitude,height and horizontal position.In attitude calculation,the pitch angle and roll angle is calculated with the gradient descent method that completes the update of quaternion.The yaw angle information is resolved with the first-order complementary filtering method.Height information and horizontal position information are solved with multi-order complementary filtering method.Then,the control algorithm of the four-rotor rotorcraft was researched.The deficiencies of two common algorithms,classic PID and fuzzy control,are pointed out.After analyzing and researching,an adaptive fuzzy PID algorithm is proposed for flight control system.simulation experiments and the flight experiments were done on the Four-rotor mini rotorcraft.The simulation results show that the adaptive fuzzy PID has the advantages of better dynamic performance,faster response,and better flight path compared to classical PID and fuzzy control.In addition,the aircraft can complete the autonomous tracking task based on this algorithm.The tracking error is small and the response is fast.The results of the flight experiments show that based on the adaptive fuzzy PID algorithm,the four-rotorcraft can complete the flight missions such as attitude,fixed-point hovering and different altitudes,which verifies the practicability of the algorithm.Finally,the research results are applied to aerial photography and water sample collection.