Laser system for Boe Bot
Angela from United States  [3 posts]
14 year
Hi, I am trying to make a "laser" navigation system for my boe bot using frequency sweeps. I am not familiar with the types of "lasers" that I can buy that are compatible with Stamp that can do this. Does anyone know what "lasers" could do this? I am trying not to use the IR led and detector from the kit...
No0bert from United States  [11 posts] 14 year
I don't think you want to use RoboRealm for such a task, as it would be much easier to implement simply with a micrcontroller. For example, in your setup you might want a servo, and mounted on this panning x axis servo, a high intensity laser beam. The servo will pan, and connected to the MCU, is a phototransistor, the phototransistor will be able to determine the T.O.F of the laser beam, thus determining the distance.

Using the pseudo code:

If time to receive laser pulse > .00001 sec
then go forward

If > .00001 sec
go backwards

I think I explained it badly, but my two cents

It might be easier with RoboRealm, but I am a noob with this program
Angela from United States  [3 posts] 14 year
Ah! Thanks so much ComputerGuy for your advice *bowing*. I will go with your suggestion.
Anonymous from United Kingdom  [99 posts] 14 year
Just a quick comment.  Since the speed of light is 3*10^8 m/s.  If the time that elapsed was 0.00001 seconds (or 0.01 ms) the light would have traveled a distance of 0.000001s * 3*10^8 m/s or 300 m /2 or 150 m!

I don't think you need to worry about obstacles 150 m away!  Unfortunately most microprocessors run order of magnitude at 20 Mhz which means that MAXIMUM time between executions is 1 / 20^6.  If we could somehow measure time in one clock cycle (we can't it takes more like 7) we still would get a distance resolution of 1/ 20^6 * 3 ^8 = 15m / 2 = 7.5 m!  (Really more like 50 meters by the time we were done.)

This is why laser scans cost $2000!

have fun!
Angela from United States  [3 posts] 14 year
Thanks Professor Mason!

lol I had to read your post a couple times to fully understand the conceptual aspect of it but you explained it really clearly... (it usually takes a little while for me to think things out)... but I think I got it!

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