An improvement for the calibration of laser gyro strapdown IMU

Under the condition of uniaxial rotation test and using norm restriction of the angular rotation vector, a nonlinear equations set including 6 uncorrelated rotations is established to define the SIMU calibration frame. A test scheme of clockwise & counter clockwise rotations is adopted to eliminate the effect of earth rotation and gyro drift errors. Linearization and iterative algorithm are put forward to resolve the nonlinear equations set with very high precision. In accelerometer calibration model, the two-order nonlinear coefficient and cross-coupling coefficient are both considered. The static multi-position method is used to calibrate accelerometers, but in each static position, it is necessary to conduct an extra vertical rotation test to determine gravitation vector in SIMU frame and the result can be used as accelerometer input reference. A static nine-position accelerometer calibration scheme is presented and the simulation results show that scale factor matrix and bias can be estimated with high accuracy, but the two-order nonlinear coefficient and cross-coupling coefficient are relatively affected by accelerometer measurement noise.