RESUMO
In this survey, we give an overview of hands-free haptic devices specifically designed for navigation guidance while walking. We present and discuss the devices by body part, namely devices for the arm, foot and leg, back, belly and shoulders, waist and finally the head. Although the majority of the experimental tests were successful in terms of reaching the target while being guided by the device, the experimental requirements were wide-ranging. The distances to be covered ranged from just a few meters to more than a kilometer, and while some of the devices worked autonomously, others required the experimenter to act as Wizard of Oz. To compare the usefulness and potential of these devices, we created a table in which we rated several relevant aspects such as autonomy, conspicuity and compactness. Major conclusions are that outdoor devices have the highest technology readiness level, because these allow autonomous navigation through GPS, and that the most compact devices still require the action of an experimenter. Unfortunately, none of the hands-free devices are at a level of readiness where they could be useful to people with visual impairments. The most important factor that should be improved is localization accuracy, which should be high and available at all times.
RESUMO
In this survey, we give an overview of hand-held haptic navigation devices specifically designed for and tested with pedestrians. We distinguish devices for indoor use and for outdoor use as the implementation is usually quite different. Outdoor devices make use of Global Positioning Systems (GPS) tracking built-in in smartphones; indoor devices use a variety of sensors, and tracking and localization systems and these are usually restricted to a small part of a building. Overall, the high success rates reported in the studies show that vibrotactile stimulation via a hand-held user interface is suitable for navigation instructions, as in all experiments (almost) all participants reached their goal. An issue for several of the indoor devices is that walking speeds were (much) lower than normal walking speeds and path efficiency was relatively low. However, these issues might be overcome with some training as in most studies there was hardly any practice time. Several of the outdoor devices seem quite close to taking the last step before commercial use. In the Discussion, we evaluate the suitability of the devices for persons with visual and/or hearing impairments. Especially devices that provide very specific instructions, such as, 'go straight' or 'go right,' seem valuable for this population.
