Computerized obstacle avoidance systems for the blind and visually impaired

This chapter gives an overview of existing devices for the guidance of visually impaired pedestrians and discusses the properties of the white cane and of conventional electronic travel aids. Also described are the disadvantages of using a standard mobile robot for this purpose. Next follows a description of the NavBelt, a computerized travel aid for the blind that is based on advanced mobile robot obstacle avoidance technology. The NavBelt is worn by the user like a belt and, via a set of stereo earphones, provides acoustic signals that guide the user around obstacles. One limitation of the NavBelt is that it is exceedingly difficult for the user to comprehend the guidance signals in time to allow fast walking. This problem is effectively overcome by a newer device, called GuideCane. The GuideCane uses the same mobile robotics technology as the NavBelt but it is a wheeled device pushed ahead of the user via an attached cane. When the GuideCane detects an obstacle it steers around it. The user immediately feels this steering action and can follow the GuideCane's new path easily and without any conscious effort. This chapter describes the GuideCane system, including the mechanical, electronic, and software components, followed by a description of the intuitive user-machine interface. The chapter ends with a discussion of the GuideCane's novel information transfer approach and its advantages and disadvantages in practical term.