Research On Attitude Control System Of Quadrotor UAV Based On Kalman Filter

The four-rotor UAV,referred to as the four-axle,rises by the thrust of the aircraft caused by the rotation of the propeller.The four propellers of the aircraft are the same size and symmetrically distributed.The simplest four-rotor aircraft only need to achieve various maneuvers with different relative speeds between the propellers.The four-rotor UAV has many advantages such as convenient maintenance,mechanical modularization,mutual decoupling of motion,no mechanical wear and rapid,real-time acquisition and transmission of image information;it brings excellent experience to users.It occupies a vast space in military use and civilian special purposes.Based on the research status of four-rotor UAVs at home and abroad,this paper designs and studies the UAV control system.The flight principle and basic structure of the quadrotor UAV are introduced and analyzed.According to the aerodynamic principle,the dynamic model of the four-rotor UAV and the equation of motion mechanics are established,and the coordinate system of the quadrotor UAV is established.To resolve the problem due to drift and noise in attitude estimation process of MEMS inertial measuring unit on quadrotor,an extended Kalman filter is presented.The design of the hardware and software system of the drone uses a modular design idea.The overall hardware of the four-rotor aircraft control system was designed,and the selection of each module device and the hardware circuit diagram were introduced.In order to verify the feasibility of the attitude analysis algorithm,a four-axis UAV experimental platform was constructed.The STM32F4 series MCU was selected as the main control processor of the UAV.The MPU9250 sensor was used as the inertial measurement unit to complete the data acquisition,and the NRF51822 wireless communication module completed the information exchange.Using the code of Keil MDK software to write and analyze several algorithms for attitude calculation,Matlab software tool draws the graph of the attitude angle obtained by various algorithms,and compares the waveform of the attitude angle analyzed by each algorithm.Finally,the extended Kalman algorithm is chosen as the attitude algorithm of the system.Experimental results show that the present improved attitude fusion algorithmhas advantages in terms of higher estimation precision and lesser drift and noise errors of the final attitude angle in different conditions,and is easy to implement in aircraft control system.