Restriction-free Initializations for Low-cost and High-rate Integrated Navigation Systems Even in GNSS Challenged Environments

Jacques Georgy, Zainab Syed, Husain Syed, Zhi Shen, Chris Goodall

Abstract:	Although Global Navigation Satellite Systems (GNSS) represent an important part in navigation systems for control and guidance applications, but alone they cannot fulfill the full requirements of these applications. Navigation systems used for control and guidance need to be reliable, accurate, real-time and continuous. Some applications also require high-rate output from the navigation system. GNSS receivers alone cannot be used for control and guidance applications in environments with degraded or denied satellite signals. The common solution to solve the problems in GNSS-only navigation is to integrate GNSS with inertial sensors. In order to assure the required levels of accuracy for control and guidance applications, higher end inertial sensors are used for applications that can afford them. Micro-electro-mechanical-systems (MEMS)-based inertial sensors are low-cost, light weight, compact, and have low power consumption; all these features give them advantages to be used in navigation systems. The drawback of MEMS-based inertial sensors is their complex error characteristics, including high drift rates, bias instabilities, and high noise levels. Appropriate and robust inertial sensor error modeling is mandatory in order to use these sensors for accurate navigation. This paper presents a real-time navigation solution utilizing low-cost MEMS-based sensors with robust multi-sensor fusion and advanced modeling for inertial sensors’ errors in order to achieve the best accuracies. The proposed solution integrates a GNSS receiver with a MEMS-based inertial measurement unit (IMU), barometer and magnetometer. If an odometer input is available, the solution can utilize it to further enhance the accuracy. The proposed navigation solution is able to navigate in all environments even with degraded or denied GNSS for long periods of time. A novel aspect of the presented work is the different initialization routines that allow the integrated navigation system to begin in any scenario or environment. The presented system, on the contrary to traditional systems, comprises innovative algorithms that enable it to start in virtually any environment and scenario with or without GNSS. The performance of the proposed system has been verified extensively on real-life road tests. The results have been examined to verify the suitability and satisfactory performance of the proposed solution even in downtown trajectories with degraded/multipath or in scenarios with totally no GNSS for long durations.
Published in:	Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012) September 17 - 21, 2012 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	1279 - 1286
Cite this article:	Georgy, Jacques, Syed, Zainab, Syed, Husain, Shen, Zhi, Goodall, Chris, "Restriction-free Initializations for Low-cost and High-rate Integrated Navigation Systems Even in GNSS Challenged Environments," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 1279-1286.
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