Development of Dialogue Systems for a Mobility Aid for Blind People: Initial Design and Usability Testing
Thomas Strothotte, Steffi Fritz, Rainer Michel, Andreas Raab, Helen Petrie, Valerie Johnson, Lars Reichert, Axel Schalt · 1996 · Proceedings of the Second Annual ACM Conference on Assistive Technologies (Assets '96) · doi:10.1145/228347.228369
Summary
This paper presents the MoBIC Travel Aid (MoTA), an EU-funded system designed to increase independent mobility for blind and elderly travellers by combining Geographic Information Systems (GIS) with the Global Positioning System (GPS). The system has two complementary components: MoPS (MoBIC Pre-journey System), a desktop application for planning journeys before travel, and MoODS (MoBIC Outdoor System), a portable device providing real-time orientation and navigation assistance during journeys. The authors draw an important distinction between micro-navigation (navigating the immediate environment — detecting obstacles, following pavements) handled by traditional aids like the long cane and guide dog, and macro-navigation (navigating through the broader environment — finding routes, identifying landmarks, knowing one's position in a city) which traditional aids cannot address. MoTA targets this macro-navigation gap. The paper reports on extensive user requirements studies conducted through interviews with potential users and mobility training professionals in the UK, followed by interface design and the first field trial conducted in Berlin with six blind participants aged 25-61.
Key findings
The user requirements study revealed several critical design constraints. Users were strongly opposed to wearing headphones, as environmental sounds are vital for safe navigation — they preferred a mobile phone-like device held to the ear. Users wanted to control the flow of information at multiple levels: from basic orientation ("Am I on course?") to detailed guidance (turn-by-turn instructions) to transport information (nearest bus stop or taxi rank). The study identified three information levels: Level 1 (basic — direction, road grade, nearest crossing, obstacles), Level 2 (detailed — shops, public buildings selected during pre-journey planning), and Level 3 (transport — nearest public transport options). The MoODS interface uses a small keypad with commands divided into primary (single button press, e.g., "Where am I?", "Alarm!") and secondary (parameterized, more complex) classes. The MoPS system provides verbal route descriptions reminiscent of text adventure games — "You are looking south. In front of you are stairs leading upwards. To your right is a notch." The Berlin field trial showed promising initial results: participants found the system had great potential, appreciated being able to control information flow, and one participant noted she could find routes without MoODS after exploring them two or three times with MoPS alone. However, participants found some distance information ("After 132 meters on your right...") impractical since some had little experience judging distance.
Relevance
This paper documents one of the earliest GPS-based navigation systems for blind travellers, predating smartphone-based navigation by over a decade. Many of the design principles identified through user research remain directly applicable to modern accessible navigation apps: the importance of user-controlled information density, the danger of headphones blocking environmental awareness, the distinction between micro- and macro-navigation, and the value of pre-journey exploration for building mental maps. The finding that pre-journey route planning alone (MoPS) helped users navigate without the outdoor system is particularly relevant, as it supports the principle that understanding spatial layout before travel is as valuable as turn-by-turn guidance during travel. For practitioners building accessible navigation tools, the paper's user requirements framework — essential, desirable, and ideal information categories — provides a useful model for feature prioritisation. The observation that distance measurements in meters were unhelpful for some blind users is a practical insight that modern GPS apps still sometimes overlook.
Tags: blindness and low vision · navigation · GPS · GIS · orientation and mobility · wayfinding · route planning · electronic travel aid · user-centered design