Research On Autonomous Calibration Method Based On MEMS Inertial/Magnetic Sensor

The attitude measurement technology of carrier is widely used in many navigation fields such as military,and commercial which plays an indispensable role.Moreover,the realization of low-cost and high-precision attitude measurement of carrier has always been the goal pursued by people.Among them,Attitude and Heading Reference System(AHRS)based on Micro-Electro-Mechanical System(MEMS)inertial/magnetic sensor combination,namely Magnetometer,Accelerometer and Rate Gyro(MARG)sensor,is not only able to provide carrier attitude information conveniently and reliably,but also has the significant advantages of low cost,small size and low power consumption,so it is highly favored.However,the inherent error of low-cost MEMS Inertial / magnetic sensor directly affects the measurement accuracy of AHRS to the attitude of the carrier,and the error calibration of MEMS Inertial / magnetic sensor can significantly improve its performance and measurement accuracy.In order to effectively make up for the disadvantage of low-cost MEMS Inertial / magnetic sensor measurement accuracy,how to improve its measurement accuracy under low-cost conditions Measuring error and improving its measurement accuracy have become a hot topic.Based on the above hot topics,this thesis mainly aims at the main problem that low-cost MEMS inertial / magnetic sensors have inherent raw data measurement errors that result in low measurement accuracy.By analyzing the error characteristics of the device,an error model is established.Then how to effectively improve the measurement accuracy of the sensor,and considering that the error calibration method for low-cost MEMS devices should also meet the characteristics of low cost,the autonomous calibration applied to AHRS threeaxis strapdown MEMS inertial / magnetic sensor is studied,namely calibration method without external equipment assistance.A new three-step assisted autonomous calibration method based on the combination of MEMS inertial / magnetic sensors is proposed,and the effectiveness and feasibility of the proposed method are jointly verified through numerical simulation and physical verification.The specific research contents are as follows:Firstly,according to the working principle of MEMS inertial / magnetic sensor,the error source and error characteristics of the device are comprehensively analyzed,and they are classified and used to express the error characteristics respectively.Then,the mathematical modeling method is used to establish a unified error model for the three sensors,which accounts for the rationality and practicability of the error model from a mathematical point of view.Secondly,based on the calibration ideas of the above error model,this thesis deeply analyzes the inherent defects of the single sensor application autonomous calibration method,and uses this as a starting point to propose a new three-step assisted autonomy based on the MEMS inertial / magnetic sensor combination calibration method.This method firstly improves the classical ellipsoid fitting method to optimize its calibration effect,and then combines it with the dot product invariant method and the autonomous calibration method based on vector cross product proposed in this thesis.On the one hand,it makes up for the lack of assisted conditions required by a single calibration method and improves the existing inherent defects.On the other hand,the three-step assisted calibration method also fundamentally improves the measurement accuracy of the sensor and realizes the selfcalibration of MARG sensor without the aid of external equipment.Finally,this thesis designs and builds AHRS hardware platform for the self-calibration method proposed by physical verification.Through the two aspects of numerical simulation and physical verification,the validity and feasibility of the three-step assisted self-calibration method proposed in this thesis are verified.The experimental comparison results illustrate the calibration effect of the method.The experimental results show that the actual calibration effect of the three-step assisted autonomous calibration method proposed in this thesis is close to the calibration effect assisted by the high-precision turntable,and it can achieve the autonomous calibration of the inertial / magnetic sensor combination without any external equipment assistance.It shows that this method not only has good calibration effect for MEMS inertial / magnetic sensor combination,but also has low cost and strong applicability.Therefore,the research results of this thesis have great research value and practical significance.