The Design Of A Practical AHRS Automatic Calibration System

The heading and attitude reference system(AHRS)based on MEMS technology has widespread applications on different fields.Eliminating errors of the gyroscope,the accelerometer,as well as the magnetometer in AHRS and improving its measurement accuracy remain paramount in the field of AHRS.This thesis designs an automatic calibration system,which can calibrate sensor errors in the AHRS.The main research contents contained in this thesis are summarized as follows:(1)The establishment of sensor error model.In order to calibrate the zero offset,scale factor and non-orthogonality,the mathematical relationship between the sensor input and output is determined.Also,the error coefficients of sensors are obtained by least square fitting.(2)Mechanical structure design of calibration table.Referring to currentlyexisting research work,an AHRS calibration platform based on the "three-axes nested" structure is designed.The three axes of the calibration platform are driven by motors,which allows the three axes to rotate and fix at any angle.The MAXON motor can provide constant speed to the outer-axis when calibrating the gyroscope.(3)The realization of automatic calibration process.On the basis of the mechanical structure design,the hardware circuit and control software of the AHRS automatic calibration system are developed.The WI-FI network communication of the control system and the control interface design of the system are completed.(4)Calibration experiment and result analysis.According to the final calibration results obtained by the host computer,the data comparison experiment between the AHRS and MTI-300 is conducted.Then,the AHRS is applied to the human walking positioning experiment,which proves the validity of calibration system designed in this thesis.The calibration results can greatly improve the measurement precision of the AHRS.The validity of the AHRS automatic calibration system designed in this thesis has preliminarily verified.In the future,the functions of the calibration system and the calibration algorithm will be further perfected to improve the accuracy of the calibration system.