Research On The Calibration Method Of Flexure Gyro Strapdown Inertial Measurement Unit

With the development of inertial technology, it is required to make simple structure,reliable performance and low cost gyros. Flexible gyroscope has developed in such demand.Firstly, the relationship among calibration errors of accelerometer model coefficients, indexing table errors and alignment errors is analyzed, then an accelerometer is calibrated on indexing table and the angular errors are measured, modifications of bias and scale factor are analyzed before and after compensating for the angular errors. The effect on calibration accuracy of accelerometer error model coefficients of the angular position errors and installation attitude errors of indexing table is analyzedSecondly,flexible gyro unit error model is established,which contains 21 error parameters. The uniform design is introduced into calibration program to screen 10 representative positions from so many position combinations of turntable test, which is basis for the use of D-optimal criteria. 21 gyro unit error model parameters are identified by position tumble test combined with angular rate test. The identification of misalignment provides identification for the result of systematic calibration.Thirdly, IMU output error model and attitude transformation matrix of systematic calibration process are established successively. The navigation speed errors and parameters of IMU error model are derived, and identifiability of error parameters is analyzed. On this basis, the identification method and rotary method for the identification simplified IMU error model of 21 error parameters are designed, only using the navigation speed errors. With additional accelerometer outputs, full IMU error model of 24 error parameters are identified as well.Finally,the structure and realization of simulation of IMU output error model calibration based on Matlab are elaborated. Trajectory generator is designed to simulate the aircraft motion to produce angular velocity and specific force needed by INS, so that INS can be under the required attitude, the information inputs strapdown algorithm and navigation errors are calculated, then the parameters are identified by calibration algorithm studied. After compensation for the impact of strapdown algorithm error on the calibration results of gyro bias, the recognized result and initial set value are very close. The results show that: the systematic calibration method only using the navigation speed errors in rotation stage studied in this paper is right.