Algorithm of Integration of the Strapdown Inertial Navigation System and Magnetometric System for Navigation of Aircrafts

Аuthors

Bobronnikov V. Т.^*, Kadochnikova A. P.^**

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: vlbobronnikov@yandex.ru
**e-mail: arkadochnikova@gmail.com

Abstract

The present research paper focuses on the task of integration of inertial and magnetometric sensors for navigation of an autonomous flying vehicle. The actuality of the problem is based on specifics of widely used strapdown inertial navigation systems (INS). In the absence of additional navigation aids to supplement INS, zero drifts of gyroscopes lead to errors in the angular rate measurements, which result into so-called «angle drifts», accumulated proportionally to the vehicle operation time.
Authors of the article consider the opportunity to reduce these errors by augmenting INS by magnetometric subsystem. For this purpose, a three-axis magnetometer should be installed on board. The magnetometer measures total magnetic-field vector at the current point of the operation. The developed algorithm of coprocessing of inertial and magnetometric measurements is described in the body of the paper. Providing that pitch and roll drifts are compensated, the algorithm gives improved estimate of the course angle. It is assumed that pitch and roll drifts could be estimated with satisfactory accuracy by processing measurements of the accelerometers during the periods of the vehicle straight-line motion.
To verify the algorithm performance the simulation model of the integrated system operation was used. The model of magnetometer measurements implements components of magnetic field conditioned by the Earth and the vehicle frame. Mean value, variance, and variation range of the course angle estimation error were used as performance indexes. These statistical characteristic were estimated with respect to simulation time.
Simulation results given in the concluding part of the paper prove the operating capability of the algorithm developed. Width of the variation range of the integrated navigation system resultant error is reduced in 40 times in comparison with the variance range for the sole strapdown system error. It was shown that efficiency of the algorithm is degraded in presence of inexact estimates of pitch and roll angles. Based on the results, authors suggest modification of the scheme of system integration and improving the designed model. The conclusion also contains recommendations on using the integrated system on board of flying vehicles.

Keywords:

integrated navigation system, magnetometric system, simulation model, strapdown inertial navigation system, aircraft

References

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