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Sensory 6: An electronic travel aid for blind persons

Since the end of the Second World War, several electronic travel aids for blind people have appeared on the market. These have taken a variety of forms. Most have operated on the principle of either ultrasonic radar or a laser beam with triangulation to determine target range. Environmental information is relayed to the user through an audible code or tactile stimulation. The devices have come in a variety of forms: hand-held, chestmounted, head-mounted, and built into a guide cane. Unfortunately, all of the more successful electronic travel aids have one problem in common: they are too expensive for the average blind person. In 1983, E.L. Bryenton and Associates, Inc., (BRYTECH), entered into a contract with the National Research Council of Canada to investigate the feasibility of the design and manufacture of an electronic travel aid for the blind which would be easy to use and reasonably priced. In the spring of 1984, ten early prototypes were delivered to NRC for evaluation. Prior to the start of the prototype design, a series of trials was carried out with blind and blindfolded sighted subjects. These investigations were run both in Ottawa at the facilities of the Canadian National Institute for the Blind and in Kingston at Queen's University. These trials employed a number of commercially available travel aids and were formulated to determine the most useful features to be included in a new design. The preliminary prototype units were evaluated by both orientation and mobility (O&M) instructors and blind subjects. Several design changes were identified that were incorporated into what was hoped would be the final form of the Sensory 6. In the fall of 1985, the Sensory 6 was unveiled at a symposium of O&M instructors in Toronto. In early 1986, a series of instruction sessions and trials took place at a number of locations across Canada. These trials provided the opportunity of evaluating the device's performance in a wide variety of environmental conditions. A few more minor problems were uncovered during this process and were corrected. During the whole period of design and manufacture, the various stages were monitored and checked by a blind consultant on staff. Design parameters The definition of needs, design, evaluations and field trials progressed through a series of iterative steps to produce a final design. As a result of these evaluations, a number of desired features and characteristics became apparent as essential to the design of a successful electronic mobility aid. Head Mounting-As most blind travelers will use either a cane or guide dog with one hand, or carry a purse, brief case, or parcel with the other, hands-free operation was necessary. Also, scanning was essential for shore-lining and locating objects off the travel-path; thus, head mounting was desirable. Na1Tow beam width-Test subjects indicated that, when traveling, they preferred information on a clear travel path sufficient for their body to pass. This was more important than general environment information, provided it was possible to scan off the travel path when desired. Another requirement was that right-left information be provided so that appropriate action may be taken to avoid obstacles. This requirement necessitated that very narrow beams should be projected by the device with stereo data supplied to the user. Information codes-The users identified a need for a simple audible code that would be easy to learn and unambiguous. In its final version, the Sensory 6 remains absolutely silent when no object is within its range. When an object is encountered, it emits a series of beeps or tones. A lowpitched tone indicates an object at max-