Research And Implementation On Micro Integrated Attitude Determination System Based On MIMU And GPS For Micro UAV

Micro Unmanned Aerial Vehicle(MUAV) has been developing rapidly in the military and civilian application, because of the advantages of low cost and power consumption, and high performance of maneuverability and stealth. Attitude and Heading Reference System(AHRS) can provide attitude and sailing information for attitude stabilization loop in UAV, which is one of the essential avionics system of aircraft for flight safety. The conventional AHRS is so expensive and heavy that it is not suitable for MUAV. The goal of the paper is to develop an AHRS for MUAV. The system is used to calculate the MUAV's real-time attitude.Firstly, the model of sensor errors is built after analyzing the error sources of MEMS sensors. In order to calibrate and compensate the deterministic errors of MEMS accelerometers, MEMS gyros, and magnetometers respectively, the calibration methods are proposed based on gravity field excitation, constant speed excitation, and recursive least squares method after analyzing the characteristics of MEMS sensors errors. The precise model of gyroscope random error is built based on time series analysis method, and then the random error of gyroscope is filtered by Kalman filter.Then, a method using GPS derived accelerations is proposed to improve attitude measurement accuracy under the high maneuverability, because the AHRS based on the gravity field and magnetic field vector observations is susceptible to motion acceleration. Considering the characteristics of MUAV's movement, GPS's Doppler velocity measurement is used as observations and Kalman Filter equations are built on the JERK model to export the motion acceleration. The compensated output of the accelerometer and magnetometer is preprocessed by gradient descent method to obtain quaternion feedback correction in complementary filter. Then the preprocessed output is fused with the attitude exported by gyroscope using quaternion complementary filter with adjusted parameters, thus the high-precision attitude estimation is obtained. And a simulation experiment is used to verify the effectiveness of the algorithm.Next, after analyzing the requirement of AHRS's performance, the hardware platform of system is built based on the ARM9 microprocessor, MEMS inertial sensor and GPS(OEM board) with suitable external circuit design. A variety of anti-jamming measures are used to ensure the system's reliability in the production of AHRS prototype.Finally, the program design of AHRS is completed in ADS1.2 integrated development environment with modular design idea. Both physical verification and accuracy analysis are provided for this AHRS. The results show that this AHRS has good real-time performance and satisfactory attitude measurement accuracy both under static and dynamic circumstances.