Observability Analysis of a Miniature Inertial Measurement Unit on a Continuous Rotating Base

Continuous rotation (“carouseling”) can effectively suppress the influence of inertial sensor errors so that miniature inertial measurement units (MIMUs) can achieve north-seeking applications, which has been recently studied. However, there is a lack of observability analyses for MIMUs. Whether the state is observable or not is closely related to whether Kalman filtering can accurately estimate the error state. In this paper, the observability of MIMUs on a continuously rotating base is analyzed on the basis of simulation and collected real data. The results show that MIMUs cannot realize self-alignment because of their large heading errors in the static state. Kalman filtering can estimate the heading angle effectively in a short time by rotating continuously around the z-axis, and it can estimate the z-axis accelerometer bias quickly, as well as the z-axis gyro drift after a period of time. However, it is impossible to estimate the gyro drift and accelerometer bias in the horizontal plane because the horizontal modulated inertial sensor errors that are integrated over time will suppress the effect of errors. Additionally, the horizontal errors can be solved by the north-seeking algorithm. This study provides a method and a theoretical basis for analyzing the observability of MIMUs and evaluating their performance.