Abstract: Coarse alignment based on Inertial Measurement Unit (IMU) is considered in the case of static position. Error analysis is provided for the IMU parameters and attitude with respect to local navigation frame. An ideal IMU model is first given and ideal IMU outputs, which consist of angular rates and accelerations, can be obtained. Then, actual IMU outputs are obtained with the consideration of uncertainties in IMU parameters, including gyro drift, accelerometer bias, and misalignment deviations. A standard coarse alignment method is implemented and the transformation matrix between IMU body frame and navigation frame can be obtained directly. The coarse alignment error is analyzed and its practical meaning is given. Numerical simulations illustrate the alignment errors for three cases with different IMU parameters, and the error is compared with IMU body attitude. Finally, experimental results are presented to show that this method could help validate the correctness of IMU measurement output.

Key words: inertial measurement unit, coarse alignment, error analysis, misalignment deviation