Odometer-aided Instantaneous Signal Reacquisition for Automotive GNSS Receivers

Hans-Georg Busing, Ulrich Haak, Peter Hecker

Abstract:	GNSS-based navigation is a key enabler for future advanced driver assistance systems (ADAS). Car manufacturers identified automotive assistance systems as core devices to propose their uniqueness mainly in the luxury and upper class segments. While the precision and availability of loosely-coupled single-frequency GPS navigation satisfies the requirements of typical route guidance systems, future automotive systems especially enhancing driving safety are more demanding towards the position-ing system performance. The Institute of Flight Guidance (IFF) is currently involved in two research projects evaluating the performance of unaided traditional GNSS receivers coupled with vehicle sensor measurements such as odometers in a tightly-coupled architecture. Besides these involvements the IFF has developed a general purpose software-based GNSS receiver allowing full access to signal processing routines. The Institute of Flight Guidance uses a software environment called Automotive Data and Time-Triggered Framework (ADTF) for research in the field of ADAS and automotive navigation. In this software framework the overall system architecture is assembled by independent modules. These modules are implemented as libraries and loaded into ADTF. Data is exchanged via pins that are defined as public variables. The framework also attaches timestamps to the individual measurements and adds a data recording and playback functionality. From the general purpose software GNSS receiver that has already been presented at the ION GNSS 2010, an automotive-specific ADTF software receiver module has been derived. The software framework adds the flexibility to synchronously process measurements from vehicle sensors additionally to the IF data from the front end. This gives us the opportunity to aid signal processing in the software GNSS receiver with additional external sensors. For positioning a tightly-coupled positioning filter based on GPS raw data measurements and the rear wheel odometers is implemented. The vehicle’s motion is modelled using a kinematic relationship between the vehicle sensors and the GNSS measurements. Based on the tightly-coupled vehicle state estimation an acquisition state is processed during signal outages that enables the software GNSS receiver to reacquire the satellite signal instantaneously with high precision. In this paper the constituent parts of the system are pre-sented and the estimation of the acquisition state derived. It is shown that the system was tested in an urban scenario and the state estimations were validated with the recorded measurements.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	954 - 959
Cite this article:	Busing, Hans-Georg, Haak, Ulrich, Hecker, Peter, "Odometer-aided Instantaneous Signal Reacquisition for Automotive GNSS Receivers," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 954-959.
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