Deeply Coupled GNSS, INS and Visual Sensor Integration for Interference Mitigation

L. Ruotsalainen, M. Kirkko-Jaakkola, M.Z.H. Bhuiyan, S. Söderholm, S. Thombre and H. Kuusniemi

Abstract:	Modern society is becoming more and more dependent on accurate and reliable position, velocity and time (PVT) information acquired using Global Navigation Satellite Systems (GNSS). Unfortunately, GNSS signal is vulnerable to interference. Intentional interference, called jamming, results in degraded positioning accuracy or total loss of GNSS signals and, therefore, may cause serious damage if the jamming signals are not properly detected and effects mitigated. Deeply-coupled, also referred to as ultra-tight, integration of GNSS and Inertial Navigation System (INS) uses information obtained from the inertial sensors, namely gyroscopes and accelerometers, to aid the GNSS signal processing algorithms. The measurements obtained using INS are not affected by jamming and therefore the integration results in a system with enhanced robustness to interference. However, the performance of INS suffers from measurement biases that accumulate to large position errors with time. Typically deep-coupling corrects the above mentioned INS errors using the GNSS signals, but if the jamming continues for a longer time forestalling the use of proper GNSS signals, degradation of the position solution will incur after some period. Visual sensors, i.e. cameras, are feasible instruments for constricting the growth of the errors and are resistant to GNSS jamming. In favorable environments and special camera configuration, camera attitude and translation between consecutive images may be detected. These measurements may further be used for mitigating the errors in INS observations. Deeply-coupled integration of the visual measurements, INS and GNSS will further improve the robustness of the positioning accuracy in situations where the jamming is not only momentary. This paper presents a deeply-coupled GNSS, INS and visual sensor integration algorithm. The paper will also discuss experiments and results assessing the robustness of a system employing the developed algorithm in a jamming situation. As far as the authors know, this is the first study discussing the deeply-coupled integration of GNSS, a consumer grade INS and measurements obtained using a monocular camera. The performance of the developed algorithm is experimented in a jamming scenario where the signals are deteriorated using a cheap jammer. The performance of the deeply-coupled GNSS/INS/visual sensor system in a jamming situation is superior to a GNSS only solution as well as to a deeply-coupled GNSS/INS integration without visual sensor. As a conclusion, the deeply-coupled integration scheme is a powerful method for interference mitigation.
Published in:	Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014) September 8 - 12, 2014 Tampa Convention Center Tampa, Florida
Pages:	2243 - 2249
Cite this article:	Ruotsalainen, L., Kirkko-Jaakkola, M., Bhuiyan, M.Z.H., Söderholm, S., Thombre, S., Kuusniemi, H., "Deeply Coupled GNSS, INS and Visual Sensor Integration for Interference Mitigation," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 2243-2249.
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