Tow Dimensional Touch-Sensing Navigation System using Picture Processing for Visually Handicapped Person

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The two-dimensional touch-sensing pad has been designed and tested for a tow-dimensional touch-sensing navigation system. The touch-sensing pin is a small pin or actuator on which a visually-handicapped person can recognize information by touching with his/her finger. The two-dimensional touch-sensing pad consists of a matrix of the touch-sensing pins embedded in a resin-board. The touch-sensing pin has a cross-section of 1 square mm, and can moves 0.5mm. The touch-sensing pins are controlled by a computer. The material of touch-sensing pin is piezoelectric crystal, and it physically extends in shape when high electric voltage is applied on it. We have considered various piezoelectric crystals in terms of physical displacement, robustness, and electrical characteristics. As a result, an ultra-sonic actuator with traveling-wave type has better characteristics for touch-sensing pins rather than piezoelectric crystals. We have tested a two-dimensional Touch-sensing pad using ultra-sonic actuators (5mm length) and high speed driving circuit connected to a embedded microcomputer. As a result, the touch-sensing pins has a velocity of 1-5 mm/sec providing sufficient characteristics for the pad. In addition, each touch sensing pin has no uniform characteristics depending upon ambient temperature and moisture causing sticking phenomena.