So as usual. doin some last min burning man projects.
Looking to add a sensor to detect when an art car is driving or when it is stopped/park.
adding some ’ simple’ led tank treds to the turtlebot but would like to have it in motion with the car and stopped an do something else when stopped.
i wa s thinkin using PIR sensor but thinking the vibration would cause it to be unreliable.
accelerometer?
anything i could track speed too?
GPS!
(Or vibration sensor.)
not sure i can source it in time. will be checking my local shop tomorrow.
i should note the art car is 1300miles away from me currently
How about running copper tape around the steering wheel and turning it into a capacitive touch switch? It assumes a particular driving habit, but at least it would be easy to implement.
Another solution could be FSR on gas pedal.
How about the sort of thing they use on bicycle speedometer? Could probably rip out the guts from one and attach it to the wheels?
Can you add a magnet to the rim? (something like a window Reed Contact). Everytime the magnet travels by the Reed will switch.
You could read motion with a hall sensor. You need Unipolar or Omnipolar (Bipolar and Latching won’t work)
IR emitter and detector pairs with a reflective element on the wheel - but I guess in the desert it will become unreliable
Photointerrupter when you can attach an encoder wheel
Depending on the car, maybe take an analogRead of the throttle position sensor? A little less reliable than GPS/physically checking the wheel for movement but you’d still get a fairly accurate determination of whether someone is actively accelerating versus idle/stopped.
Make a DIY vibration sensor, aka two wires that bump together and apart, and just measure the how-much-they-bump. Or cut two long strips from an aluminum can and nail them to a board so they brush together when jostled. Or maybe a piezo speaker can be used in reverse as a vibration sensor?
If you look at the insides of a (cheap) vibration sensor, you’ll an idea how to DIY one: one pole is connected to a coil of springy wire. The other pole is connected to a stiff wire that runs down the middle of the coil. When the device is bumped, the springy coil touches the center pole. http://www.electroschematics.com/wp-content/uploads/2014/03/vibration-sensor.jpg Here’s an even better view: http://cdn3.bigcommerce.com/s-vt19phz/product_images/uploaded_images/adafruit-medium-vibration-sensor-switch-from-tronixlabs-australia-500.jpg
And for those who haven’t seen Kobakant, you MUST check out this site:
http://www.kobakant.at/DIY/?cat=26
TONS of DIY sensors and other DIY electronics hacks. e.g. http://www.kobakant.at/DIY/?p=3099
No no no 
hehe
Just measure the battery voltage or current draw from the cigar lightener.
I’ve seen a device vorking as a fm transmitter to the radio. Sending out some cool sounds depending on the RPM of the motor. “Just” measure the pulses and you know it 
@Simon_Hermansen thats brilliant. I love the idea of using the battery voltage to measure RPM, genius.
or use a OBDII (OBD2) adapter that connects to the diagnostic connector found in all modern cars. The adapter transmits vehicle data
I am with Simon - grabbing OBD (or Can Bus) is relatively easy - you can get an OBD interface from Ebay for $10-20. This is a good source of instant info: http://forum.arduino.cc/index.php?topic=95037.0
and here: http://forum.arduino.cc/index.php?topic=171058.0
and here: http://arduinodev.com/hardware/obd-kit/
it would actually be very cool to have lights reacting to to the cars health, speed, RPM and such!
magnet and hall-sensor
