Research Of Imu Calibration Method On Horizontal Three-Axis Turntable

The accuracy of inertial instruments is of great significance to ensure the navigation accuracy of INS.Generally,there are two key factors affecting the accuracy of inertial instruments.The processing and manufacturing accuracy of inertial instruments and the testing accuracy of inertial instruments are two key factors.It has become more and more difficult to improve the accuracy of inertial instruments from the aspects of manufacturing materials and processing technology.It is restricted by the limit of manufacturing accuracy and the huge manufacturing cost.A more economical way to achieve greater breakthroughs is to improve the calibration accuracy of inertial instruments.Therefore,how to accurately measure the error coefficients of inertial components by calibration technology and compensate for the error coefficients in the navigation process to achieve the purpose of improving the overall navigation accuracy of the system has become an important process.This paper will focus on the calibration method of inertial measurement unit on horizontal three-axis turntable.Considering the characteristics of both angular velocity component and gravity acceleration component alternating when the outer axis of horizontal three-axis turntable rotates,the method of IMU's separated calibration and systemmatic calibration on horizontal three-axis turntable is emphatically studied.The identification and compensation of IMU's error parameters are achieved by establishing accurate error model,designing reasonable position arrangement scheme and simulation analysis.Good results have been achieved.The error of IMU is analyzed.The error characteristics of inertial devices,several error sources of inertial navigation system and error models of accelerometers and gyroscopes are analyzed.Then,several error equations of strapdown inertial navigation system are introduced,such as velocity,position and attitude error equations.The separated calibration method of IMU on horizontal three-axis turntable is studied.Error calibration models of accelerometer and gyroscope are established separately on horizontal three-axis turntable.Two calibration schemes are designed,namely,hexahedron calibration scheme and dodecahedron calibration scheme.Accelerometer is calibrated by static multi-position test on horizontal three-axis turntable,gyroscope is calibrated by single-axis rate and double-axis position tumble test method.The least square method is used to calibrate the error parameters of accelerometer and gyroscope.After that,the accuracy of accelerometer and gyroscope is analyzed and simulated,and the error models of accelerometer and gyroscope are calibrated separately with the vertical three-axis turntable.A systematic calibration method based on navigation speed error for IMU on horizontal three-axis turntable is studied.The relationship between the error parameters of IMU and its proof process are given.A hexahedron calibration method with the middle and inner axes in angular position and the outer axes in angular rate state is proposed.Then,the least square method is used to calibrate the error parameters of accelerometer and gyroscope.After that,the accuracy of accelerometer and gyroscope is analyzed and simulated.This method is not only simple and feasible,but also solves the problem of coupling the installation error angles of accelerometer and gyroscope in the systematic calibration of IMU,and can effectively restrain turntable errors.Another systematic calibration method of IMU based on specific force observation on horizontal three-axis turntable is studied.By establishing the relationship between the specific force measurement error and the error parameters of IMU,and based on the design of a reasonable and appropriate position arrangement scheme for the horizontal three-axis turntable,and deducing the relationship between the observation quantity and the coefficient to be calibrated under each rotation arrangement,the least square method is used to identify the parameters to be calibrated for IMU,so as to achieve the calibration of the error parameters of IMU.In addition,the simulation analysis shows that the position arrangement scheme based on the horizontal three-axis turntable is less than that based on the vertical three-axis turntable,and the calibration scheme is simpler when the same accuracy level is obtained and the calibration accuracy of accelerometer error coefficients has been improved obviously.The conclusion that systematic calibration method can achieve high-precision calibration without precision turntable is verified.It lays a foundation for the realization of IMU high-precision field calibration.