InfraRed = gps ?

[Kevin Watson]

Originally Posted by mightywombat

ok. So you'd have one beacon tracking each of the different types by how often they recieve envelopes? How exactly are you going to figure out the distance from the emitter? Will the signal be recognizeably weaker the farther you get from it?

This is the sequence of events within the beacon state machine:

1) The type-0 beacon is allowed to flash for 1ms. As the carrier frequency is 40KHz, this means the LED will flash on and off 40 times.

2) A delay of 3.5ms where both LEDs are off. This allows reflections to die off before...

3) The type-1 beacon (on the other side of the field) is allowed to flash for 2ms, which means the LED will flash on and off 80 times.

4) Another 3.5ms delay is inserted where the LEDs aren't flashed before the state machine starts all over again at #1 above.

If you add up all of the periods (1ms + 3.5ms + 2ms +3.5ms), you'll see that the total time needed to flash the beacons is 10ms, which means the beacons flash at a 100Hz rate.

You can calculate your distance and angle to the beacon by using a little trig (exercise left to the student ).

-Kevin

[mightywombat]

OK. That makes alot of sense and is actually pretty cool how it works. Thanks for explaining it.

[Anthony Kesich]

Originally Posted by Justin Stiltner

If you were only tracking one beacon, couldent your robot be anwhere on a circle scribed about that beacon with the radius of the 2 sides of the triangle formed from the sensors? IE you know how far away from the beacon, but unless you are using crab, or omni drive and can keep the orentation of your robot square in relation to the sides of the field... you cant really tell your exact feild position.... or is there something that im missing

Gyroscope with integration. Your programmer should be able to do this of he's/she's worth his/her beans. This way you know your angle relitave to the field and sdjust the trig respectively. All i know is triangulation is going to cost me a pretty penny in paper. Also, you can use the gyroscope in conjunction with some accelerometers to have a backup positioning system.