1. Department of Precision Instrument, Tsinghua University, Beijing 100084, China; 2. Weapons and Control Department, Army Academy of Armored Forces, Beijing 100072, China
Abstract：Micro inertial measurement units (MIMU) based on micro-electro-mechanical-system (MEMS) designs are very small and light with low power consumption, but they have large inertial errors that limit applications. The rotation modulation technique was used to reduce the influence of these errors so that the MIMU systems can more accurately identify the northern direction. However, there have been few observability analyses of MIMU devices with the observability closely related to whether the Kalman filtering can accurately estimate the error state. This study analyzes the MIMU observability using Kalman filtering based on measured data for stationary, multi-position and continuous rotation conditions. The results show that the heading angle error in the stationary condition is quite large and the device cannot be self-aligned. A multi-positioning scheme with rotation around the heading axis and the pitch axis makes the MIMU error state completely observable. With continuous rotation, the Kalman filtering can quickly estimate the heading angle and the azimuth accelerometer bias with the azimuth gyro drift estimated after a short period of time. The gyro drift and the accelerometer bias in the horizontal plane cannot be accurately estimated using Kalman filtering, but they can be measured by the north-seeking algorithm. The research provides a theoretical basis for improving the self-alignment accuracy of MIMU devices and evaluating their performance.
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2020, Vol. 60 
