how to measure foot size
My lecturer was saying in the market there is a foam where the resistance changes when the pressure on the foam changes. I am assuming mayb when u increase the pressure, the foam will increase the resistance. Therefore, he was suggesting a grid method where u place multiple conductor across the foam with even spacing and send current(or some sort of signal) through each conductor. The place where the foot is there, the pressure is high and thus the resistance is high and as a result the current through that grid is going to be lower as well. So, u can tell whether the foot is there and you will know how many grid lines has lower current. Since in the beginning we use even spacing between the grid line and now we know how many grid line has lower current, the work left is just multiply the number of grid line with the spacing and we get the length.
Using this method, he said u save cost as conductors are definitely cheaper than IR transmitter and receiver and doesn't require mechanical part. However all these are theory, i havent really built a pressure sensor before. I am not sure how to send signal through those grid and i also don't know how to build an electronic equipment that will help me to identify the signal that is lower and calculate the length for me? Could it be some sort of adder or multiplier which will do that job?