Problem:
I want an easy way to indicate to motorists which direction I’ll be headed when biking at night.
Solution:
Cobble together a pair of gloves, a couple of arduinos, some flex sensors, and a bunch of LEDs for fun and profit. In other words, make a glove that blinks when the index finger is fully extended.
Process:
As always, I start with a simple drawing. Being a former art major, it’s a bit embarrassing how bad these drawings always are. Regardless, the idea is that there’s a row of lights at the top of the second and third fingers, and a flex sensor at the bottom of the second finger. The power supply, switch , and arduino will be sewn into the back of the hand (on the glove of course). Since I’ll be wearing the gloves while I bike, my fingers will be gripping the handlebars about 95% of the time. All that I need to do is let the arduino know when my fingers are extended (i.e. off the handlebars and indicating a direction of movement).
I always start to prototype these projects on the Arduino Deumilanove because it’s easy to plug into my laptop for power and data transfer. I’ve got a Lilypad and a Mini but nothing beats this board for ease of use. It’s been a while since I’ve done a hardware project so I had to re-familiarize myself with breadboards and analog inputs as well as how to calculate resistance in any sensible fashion. This tutorial on Force Sensitive Resistors also pointed me in the right direction as far as hooking the whole thing up.
Once I had some code written, I hooked everything up and after a few test runs, got the lights blinking and the values on the flex sensor reading in properly. I’ve seen at a number of sites people getting values back in the 400-700 range, mine reads back in the 200-500 range. I’m pretty sure that it’s the resistor but it doesn’t matter that much; I only need to straighten the sensor past a certain threshold to get the lights blinking.
Anyhoo, this is how things turned out. Next time, I’ll document all of the actual soldering, sewing, and real life testing.
Downloads:
Preliminary code - light_gloves.pde.zip
