ARGUS: Assisting Personal Guidance System for People with Visual Impairment

O. Otaegui, J. Seybold, J. Spiller, A. Marconi, R. Olmedo, M. Dubielzig

Abstract:	Almost 300 million people in the world are visually impaired. About 90% of the world's visually impaired live in developing countries, and about 65 % are aged 50 and older. With an increasing elderly population in many countries, more people will be at risk of age-related visual impairment. People with visual impairments have striking needs for trustful navigation systems enabling for efficient mobility services, mainly considering safety and autonomy. In this context, satellite-positioning and navigation technologies available are being implemented in innovative personal navigation devices. Existing products and solutions based on GNSS (Global Navigation Satellite Systems) do not meet all of the needs of this collective and fail because they lack accuracy and integrity; they do not provide a suitable and efficient man machine interface adjusted to this user segment, or rely on costly infrastructure. ARGUS project aims to develop a personal navigation solution based on the integration of advanced user interfaces based on acoustic binaural (i.e. 3D sounds) and GNSS technologies that can guide people along a predefined track. It introduces the opportunity to develop an innovative guidance support system for people with visual impairments based on the provision of a virtual-lead-line to the end user that can be perceived and followed (three-dimensional mental map of the path to follow). This will provide “track navigation” instead of the classical “waypoint or route navigation” which is used for car navigation or people with all visual capabilities. The challenge of the ARGUS project lies in the integration of advanced user interfaces based on generated acoustic signals, with minimal interference on the perception and operation by users, so that they can move around autonomously based on a three-dimensional mental map of the path to follow and the key features of the surrounding environment. Binaural sounds create the illusion that sounds produced by stereo headphones come from specific directions and distances, based on the interaural differences. This allows users to perceive 3D sound positioning which gives them the sense of 3D navigation. The route can be selected over previously recorded tracks (natural routes: no GIS) or selecting origin and destination (city or urban scenarios). The provided route consists of consecutive geolocated points in 2D, therefore this geographical map has to be translated into a binaural sound map. Applications, which provide a binaural insight of the surrounding environment for guidance purposes in different conditions, need important information about the user’s position and orientation. The determination of these quantities is ensured by coupling GNSS measurements and measurements provided by an Inertial Measurement Unit (IMU). To reach a high accuracy of the position, the GNSS observations are corrected. Therefore, an augmentation and correction server was developed to access EGNOS (European Geostationary Overlay Service) information through EDAS (EGNOS Data Access Service). The fusion of measurements provided from the mentioned technologies by the means of Kalman filtering lead to an enhancement of accuracy, availability, and integrity, concerning the user’s position and attitude. On the one hand, the observations of a GNSS receiver, such as code-pseudoranges and Doppler on L1, serve as absolute positioning information. Doppler contributes also in the determination of the user’s velocity. On the other hand, acceleration and angular rate measurements provided from an IMU are used for attitude determination and for calculation of the user’s velocity. Accelerations are used to derive the user’s velocity based on reliable step detection. To reach a high accuracy of the position, the GNSS observations have to be corrected due to different influences, e.g. the ionospheric delay. Therefore, an augmentation and correction server was developed to access EGNOS information through EDAS, and to compute pseudo-range corrections for each satellite used for positioning. For the distribution of the correction information, the network transport of RTCM via internet protocol (NTRIP) is used. In addition to the navigation device, a web-based collaborative environment including a social network is developed for enabling users to share routes, data and experiences in order to increase safety or enhance the experience when performing outdoor activities. The web-based service also offers the capability of track simulation and perception – that means the user is able “go through” the track before navigation is performed in the real environment. A preliminary functional prototype with basic functionalities and using beta developments has been designed. Due to this prototype, the preliminary proof of concept has been conducted in Paderborn (Germany) in September 2012 with the intention to test the technical feasibility of the ARGUS main concept: the capability to connect tracks with GNSS real time locations and match the guidance into 3D sounds. Four expert users with different visual impairments have participated in these tests to technically assess the concept giving out very encouraging outcomes. All of them successfully accomplished assigned navigation tasks and low deviations from control points were achieved. Only 5 minutes training on users was required to obtain good performance with the ARGUS system. Additionally, some workshops took place; the last one in October 2012 in the facilities of Siemens, to which a group of 28 visual impaired and blind people attended. The tests emphasized that the idea is well accepted and the current state of the implementation is on track, following the right way to fit the user’s needs. Further demos and testing will be carried out from June 2013 to September 2013 where the whole system will be tested in different outdoor scenarios. The main idea of ARGUS won the EGNOS prize at ESNC (European Satellite Navigation Competition) 2012. The GSA (European GNSS Agency) judges highlighted the innovativeness of the idea (the pioneering approach to link GNSS with binaural technology), the importance of EGNOS to the solution, its high performance, relative commercial readiness (a prototype exists and a technology patent is being applied for), its high market potential and clear social benefits. The research work described is conducted within the project ARGUS, which is co-funded by the EU 7th Framework Program under grant agreement FP7-288841(ARGUS). The project was started in October 2011 and will be finished in April 2014.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2276 - 2283
Cite this article:	Otaegui, O., Seybold, J., Spiller, J., Marconi, A., Olmedo, R., Dubielzig, M., "ARGUS: Assisting Personal Guidance System for People with Visual Impairment," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 2276-2283.
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