Research On Distributed Calibration Method Of Inertial Measurement Unit

Inertial measurement unit(IMU)plays an important role in defense equipment and production life because of its advantages of high accuracy,low cost and small size.The accuracy of inertial devices is mainly affected by two aspects,on the one hand,the accuracy of the processing process,and on the other hand,the calibration test accuracy of inertial devices.Because of the constraints of cost and processing process,it is more and more difficult to improve the accuracy by process means.Therefore,the mainstream approach to improve the accuracy of inertial navigation is the use of calibration technology for inertial device calibration compensation.Currently,inertial devices have entered the batch production stage,the calibration of individual devices can not meet the market demand,related scholars have begun to work on batch calibration methods.In this paper,we use a distributed approach to achieve batch calibration and compensation on a low to medium accuracy turntable for the same batch of homogeneous IMUs.The work done in this paper is as follows:(1)The distributed calibration method of IMU based on specific force measurement is studied.Firstly,the device’s own errors are analyzed,focusing on the deterministic term errors of accelerometer and gyroscope,and the error model is established;secondly,the main errors existing in the strap-down inertial navigation system,including velocity error,position error and attitude error,are introduced.Finally,according to the position arrangement of multiple turntables,the relationship between the observed quantity and each error parameter of IMU is established,and the error parameters of the same batch of IMU are calibrated by the distributed method,and the simulation analysis is completed.(2)A three-axis turntable control system based on IMU data acquisition was built.The user-oriented upper computer software and the lower computer program to control the turntable were designed in conjunction with the laboratory-made turntable.The upper computer software is responsible for assisting the user to complete the control of the turntable,attitude solution,navigation solution and data acquisition to provide reliable data for the experiment;the lower computer program mainly completes the precise regulation of the three-axis turntable.The upper computer and the lower computer are interfaced to realize the control of speed,position,swing and other modules of the turntable,providing a simulation environment for the experiment.(3)Using the upper computer software to control the three-axis turntable,the distributed calibration method is used for experimental testing and the IMU is compensated by combining the calibration results.By analyzing the data before and after the compensation of the same batch of IMUs in the stationary state,the final results show that the distributed calibration method can effectively calibrate multiple IMUs simultaneously without relying on the highprecision turntable,shorten the calibration time,and meet the calibration requirements of low and medium-precision IMUs.