The use of iron filings-plaster mixture as sensor protection material to extend the range of detection for the blind guiding electronic cane

This paper presents the research and development for implementing the blind guiding electronic cane, which used with the special ceramic tiles instead of the rubber tactile tiles. These special tiles were produced from ceramic waste sludge from wastewater treatment plant which contains heavy metals. According to the result of ldquoA Study of Possibility to Use A Ceramic Tile Composed of Waste Sludge as Pathway for The Blindrdquo which the output data from Hall effect sensor has been analyzed, it indicates that these ceramic tiles can be used as the smooth pathway for the blind. However there are some limitations: namely, the distance between the sensor and the tile is in short range which unsuitable for actual use, in addition the sensor should have an impact guard to protect itself against the damage due to the collision when the cane strikes the tile. We found that the suitable material for the impact guard is a bar of plaster mixed together with magnetic material such as iron filings which has high magnetic permeability. By the experimental result, we found that it can extend the distance between the sensor and the tile to become longer without decreasing the capability of the sensor to detect the tile. Finally the bar of protection material in various thicknesses and various proportions of iron filings and plaster was applied to the experiment and we found that the 3.0 mm-thick bar with 75% iron filings -25% plaster mixture, is one of the most suitable to use as the sensor protection.