I built a rover that I can control by wirelss router connected to a micro controller. I want to add the ability to track the location. Also, if the rover were to go out of range of the router signal, I would want it to return home using a position tracking system. Adding a GPS seems pretty straight forward, but the accuracy is +/- 6 feet or so. I think I would need a compass with the gps.
I’ll be operating the rover over and area of about 200’ x 400’, outdoors.
Does anyone have experience in using either a gps or some sort of triangulation system for robotic control or tracking? What would you suggest for components?
Also you could use a less accurate GPS to get the rover to within 10 feet of the home target then have the system switch over to an infared target to guide it back to an exact location.
super bright infrared LEDs show up really well on B&W cameras and if you pulse them they don’t take a lot of power on the average. You could therefore set up a couple of IR LED beacons at specific and known locations and use an inexpensive b&w camera to find them. so long as you have a rough idea of your general location than one or more beacons can be used to triangulate your exact coordinates. You could probably even use a solar panel to power the beacons so they never need batteries.
I like the IR idea. I’m in the process of building the docking/charging station and I’m thinking this would be good for the final guidance into the station. Can either of you point me to an emitter and receiver? Is more than one receiver required to determine the direction of the emitter?
for a receiver I was just talking about a black and white camera, possibly with an IR filter on it but that may or may not be necessary. supercircuits.com/index.asp? … rodID=5626 is a cheap possibility.
using the lens calculator, if you have the lense cranked out to 12mm then
if your IR beacon flashes once every 2 seconds for 65mS then you just have to look for the really bright spot ocurring in 1 or 2 frames every 2 seconds.
if you know where the camera is pointing relative to the front of the bot then you should be able to calculate an angle based on the position of the bright spot in the cameras field of view.
I’d think one of the standard 38-40khz IR emitter/detector setups would be easiest. Rotate the detector on the robot to find the direction of the emitter. Possibly simple tone encoding/decoding chips could be used to distinguish the different emitters.
if the beacon were continuously “on” (which in this case means modulated at 38-40KHz) this could work if you had a very narrow field of view. however if you want to pulse the beacon it seems like this could be pretty hit or miss, i.e. if you happened to be looking in the right direction at the time a pulse transmits you would see it but otherwise you would not. if you open the aperature to a wider field of view then you sacrafice anglular resolution unless you want to do some sort of dither the edges type thing.
I’d look at something like below as a starting point. The receiver would be the hard part to DIY. More “universal beacons” are available at walmart for ~$5. Bottom shows a simple way to control buttons on remote controls.
