Application of DCT-filtering on signal processing of the inertial measurement module

Abstract

This article is devoted to the analysis and processing of signals of inertial measuring modules used as part of inertial navigation systems or in research measuring complexes for conducting shock tests. The modules have a set of sensors for measuring the speed of the object, its orientation in space, the gravitational forces with which it moves, as well as the magnetic field surrounding it. Using the example of a typical inertial measurement module WT901SDCL, it is shown that the signals of acceleration, angular velocity, and angular position generated by the module have a certain fluctuation component, which deteriorates the accuracy of determining the estimated parameters, as well as to the appearance of an accumulated error in the determination of coordinates of the inertial navigation system. In such conditions, it is advisable to use secondary processing methods, namely, filtering methods. Since the information component of the signals of the inertial measurement module has significant dynamics, one of the key requirements for the filtering method is its preservation. However, a filter is also required to effectively suppress the fluctuation component. Among the currently existing filters, the filter based on discrete cosine transform (DCT-filter) has the best trade-off according to these requirements. It is shown that the use of this filter allows reducing the intensity of the noise component in the information signal by the average of 1.4 times the value of the mean square error and, accordingly, to reduce the measurement errors of physical parameters. Simultaneously, the shape of the signals after applying the DCT-filter remains almost unchanged, all sharp dynamic changes in the signal are preserved, and the absolute levels of the signals also remain the same. Thus, the use of DCT-filtering for signal post-processing in inertial measurement modules can be considered quite reasonable.