Originally Posted by
StHanley
Ive seen that one. I guess I want to see it working to understand how it works. I think there are so many options with this. I was thinking about putting the Pi in the RC. if we need to add a bird that would be OK although the weight would add up. We could add another pi externally as stage 2 to maybe track multiple cars. I'm still trying to think of how we can register a lap pass. So far we have iR, Possibly a magnet, and maybe RFID if its possible.
One of the other thing I was thinking about is the capabilities to also control the server and speed control are definitely there. That would be another stage.
There are also all sorts of sensors you can add to these things for temp, rpm, speed, and gps, camera if cheep enough.
I need to put them in order of priority. Pi announces another mini board the other day too. From what I understand it may expand the io capabilities. Lets see what happens with that when its released. Until then, Im going to work on what I see is out there. Your thoughts?
Definitely, the raspi can be installed in an RC and powered through the receiver, but for anything smaller than 1/8th scale, it would alter the balance of the car too much. Controlling and programming the ESC can be done for ESCs that allow on-the-fly programming such as the new Sanwa ESC, but then questions on how to send commands in a user friendly manner come into play.
Controlling the servo and ESC are achievable, since signalling is PWM which the GPIO supports but if you have a modern era 2.4 controller, why would you want to do that, unless you want to make a car that runs a pre-programmed route which is repeatable.
There are many breakout boards that can be connected to the pi, all doing different things, but doing so would require a few different boxes connected to an already large size for even an 1/8th scale car. I guess in order of priority, if telemetry is important, then the breakout boxes handle the different sensors, a micro wifi adapter on the pi handles transmission and a base computer receives and compiles the data into a readable format. The resolution of the results may be an issue since am not sure if it can handle polling 3 or 4 different sensors in half or fifth of a second intervals and transmit it almost instantly. 1 second polling might not cut it unless your track is really huge and a rough graph is acceptable.
If it can be done, do note that if running wifi, it will have to be 5ghz since most, if not all modern radios run on 2.4 ghz. That might be a bit of a problem for the pi since the wifi adapters I see almost all run on b/g/n which is 2.4ghz. So this may cause interference with the radio control.
If magnet will be used for lap timing, then you can only time 1 car at a time since multiple magnets on different cars will all read the same. RFID is possible, but you would need to create a decoder loop which will require additional hardware. If cost is a concern, IR is the way to go. I got my IR receiver for less than $2. No additional hardware needed as i plugged it into a ribbon cable I had which was connected to the pi. But IR is only 1 way and even if IR can register a 'pass' on the line, I don't think that it can handle multiple data transmission in such short a time, though it can be done but it takes more time to transmit the data than the time it takes to make a pass.
I think you have to limit the scope of your project, define your requirements and set your parameters. It's a good idea, but at least for me, aside from a creative challenge, has the potential to become too complicated by wanting it to do too many things.
If you want to control a car, check out this kit:
http://pi-cars.com. Has all the stuff you need, and instructional on programming it as well :-)