The two-fold aim of this chapter is to present the design process of an interface for a mobile navigational aid for blind pedestrians and a set of rules for producing route descriptions for these users, as well as the methodology used to develop them, rooted in a user- and activity-centered approach. We first present the state of the art of wearable verbal navigational aids and what might still be lacking in their conception, and propose a reusable user- and activity-centered approach designed to complement already existing and future systems. Case studies fitting into this approach are next presented: route descriptions produced by blind pedestrians were analyzed; the production rules were extracted and tested in urban areas. Results reveal these rules, the specific database features, the required user profiles, and the precision of localization necessary for assisting blind pedestrians’ wayfinding in urban areas. Finally, future trends in mobile guiding tools for the visually impaired are examined.
Key Terms in this Chapter
Oriented Locomotion: Locomotion is the movement of one’s body around an environment, coordinated specifically to the local or proximal surrounds, the environment that is directly accessible to our sensory and motor systems at (a) given moment(s) (or, at most, within a few moments). It solves behavioral problems such as identifying surfaces to stand on, avoiding obstacles and barriers, directing our movement toward perceptible landmarks, and going through openings without bumping into the sides. During oriented locomotion, people attend to their surrounds, to landmarks, and to their own movement, to reach a perceivable goal.
Activity-Centered Approach: A methodology for the design of systems and their interfaces, based on the actual activity of the end-users in the targeted context and in terms of the user profile, the environment and the goal-directed activities performed. The latter are in-dissociable and form the core of the design process.
Navigational Aid: Any device that supports way finding in an unfamiliar environment
Wayfinding: In contrast to locomotion, way finding is the goal-directed and planned movement of one’s body around an environment in an efficient way. Way finding requires a place goal, a destination we wish to reach. This destination is not in the local surrounds. Way finding is coordinated distally, beyond the local surrounds directly accessible to our sensory and motor systems at a given moment. Memory traces of the surroundings, internally or externally stored in artifacts such as maps, play a critical role in way finding. When we way find, we solve behavioral problems involving explicit planning and decision-making, problems such as choosing routes to take, moving toward distal landmarks, creating shortcuts, and scheduling trips and trip sequences.
Techniques for the Analysis of the Activity: These are field study approaches that allow gathering information on the needs and wants of end-users, as well as the subject’s organization of the activity (the mental operations performed, the informational items to which these operations apply and the resulting physical actions performed).
Visually Impaired Pedestrians: Persons suffering from total blindness, central or peripheral visual deficiency… that will differentially impact their abilities to perform oriented locomotion tasks.
User-Centered Approach: A methodology for the design of systems and their interfaces, based on the generic characteristics of the end-users (often gathered out-of-context) used to decide on which model the design of the device is to be based.
Rules for Producing Verbal Instructions: Formal production rules that specify the linguistic forms to be provided to pedestrians for way finding and the moment to provide them.