One of important functions of imaging tactile sensors is object recognition in the environment where visibility is low. To achieve this function, sensor surface deformation by object contact must be detected. In this paper, a sensor system using light conductive plate is suggested for imaging tactile sensor.
If a light is irradiated to the side of a transparent plate which is in the air, the irradiated light is reflected fully, and traveled in the plate, so far as the incident angle is less than the critical angle et the boundary area between the plate and air. When a white elastic sheet which has an uneven structure in below is put on the plate and a force is applied on the sheet, the protuberance parts of the sheet is compressed, and adhered to the plate. The fully reflected lights are scattered at the adhered Eoundary area because the full reflectance condition is broken off at that area.
The size of adhered area is depend on applied pressure or displacement, and the intensity of the scattered lights is in proportion to the size of adhered area. Therefore, if the pattern of scattered lights is detected at the below of the plate, it is possible to evaluate the pressure distribution and deformed state which is applied at the sheet.
According to the above principles about the sensor, we designed a new sensor system which consists of acrylic plate, elastic sheet, plastic light fibre, phototransistor matrix, light source, and microcomputer for tactile information process etc.
Relations between sheet displacement and detected intensity of light is analized, and object pattern reconstruction is experimented with this sensor system.
As a result, it was found that this sensor system was sufficient to get a good geometric characteristic of the pattern with information processings.
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