No abstract

In this paper, a piezoelectric sensor is used to sense the pressure generated when steps are taken. The output voltage generated by the piezo electric sensor is passed through a cascade combination of two voltage comparators, (LM 358 AND 741), the output of which is HIGH(5V) when a piezoelectric sensor is pressed and the voltage across the sensor goes above the threshold. The output of the comparators is then fed to the counter circuit (implemented using 4026 IC), which counts the number of times the output is high/steps are taken. Finally, the output is exhibited on a 7-segment display common cathode display.

Less than 3% of 145 million blind people in developing countries at present are literate [1]. At present, in most of the cases, speech output has been the medium for blind people to access materials. For content which require deep understanding such as technical texts etc., it is not an appropriate modality, moreover blind people are more accustomed to braille transcripts and adaptability issues to all audio resources is difficult. And thus, arises the need for a cheap, easily adaptable, less complex solution to the problem. Braille points are varied arrangements of raised dots representing characters which are identified by touch by visually impaired people. Here we discuss in detail, development of a dynamic/refresh-able Braille display which presents Braille points by the up-and-down movement of pins using a completely new, first of its kind, Cam actuated mechanism with just two actuation points instead of a standard 6 used by every single refresh-able braille board in the world at present. Two nested shafts having 8 arrays of precisely calculated and placed cam, each were responsible for keeping the pins in up and down state. The shafts were actuated using two micro-servo motors placed next to each other. X degree rotation of servo after transmission through gear and subsequently shaft resulted in a particular configuration. Henceforth calibration was done so that all braille alphabet could be produced with specific servo rotations.