Last night, when I got back from the studio, I arrived in my flat to find a delivery from Proto-Pic – inside were almost all of the components I will probably need for my mk 1 prototype. I didn’t want to waste any time to get the tech working despite my eagerness to build a chair – if I run out of time I can at least source a chair for demonstration purposes but it would be more difficult to demonstrate the technology if I don’t get it done. Anyway, I can work on sketches and model chairs in my down time when the studio is closed.
So today was the start of my journey in technical prototyping for this project with the aim of getting the pressure sensor for the seat working. It took me a little while to reacquaint myself with Arduino, especially because I’m working with an Arduino Micro but luckily, it’s not really that different. Getting a good reading from the pressure sensor – that was a different story. Thanks to a fair amount of help from Ali I was finally getting somewhere.
I’ve managed to get the pressure sensor to behave like a switch, demonstrated for now by an LED. In an idle state the LED is off. Apply some pressure, and you get light. Sounds simple, but for my own benefit, I’m going to explain it:
The pressure pad doesn’t just work straight out the box – it requires a little bit of craft. What I’ve done is sandwich a pressure sensitive conductive sheet – known as Velostat – between two pieces of felt. I then stitched some conductive thread through each piece of felt – this applies a current to the pad and when the sandwich is put together, the circuit is complete. The Velostat acts like a resistor – the value changes when pressure is applied. It’s then just a case of writing out code that tells the LED to come on when the pressure reading goes over a certain threshold.
It’s a bit rough just now but it’s a good starting point. Tomorrow, I’ll try to get the transmitter and receiver built in, the input (pressure sensor) and the output (LED) can work wirelessly.