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IR detector

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Hi everyone,

I'm trying to build my 1st robot that uses IR sensors to avoid collision with obstacles at the same time that travel from one IR beacon to another IR beacon. My question is how can I use phototransistor to build IR detector to detect only the beacons' IR without interfering with the obstacle sensors? thanks.

make sure only one IR source is switched on at any one time.
if you have you beacons switch on for a set time and then off for a set time, have the robot scan for the lit beacon.
once your robot knows the timing sequence of all the beacons it can see it is free to use it's own IR emitters in the "dark" phase.

make sense?


I'm using Sharp IR sensors that have emmitter and detector altogether to avoid obstacles and are "on" state all time. The two IR beacons transmitt IR @ different frequencies continuously, there is no "on" "off" state. My Robot's mission is to search for the first beacon and lock to that beacon and to reach there. Once it reached the 1st beacon it will start searching for the second beacon and do the same thing. My problem is how can I use IR detectors only to detect IR beacons and direct the Robot to the detected beacon? I guess I made my question a little bit clearer this time. I hope you guys will help me out. Thanks

this won't require timing
switch on and off the robot's emitter once every few milliseconds
have the beacons only turn on it's own emitter when it detects no emitted ir light from the robot, at which point, as the robot knows its own emitter is off, it will know the only source of ir is the beacon. once the robot turns on its own emitter, the beacon shuts off, and as the robot knows its own emitter is on, the only source of ir is an obstacle.

if all the emitters have the same brightness/range there should be no problem

also to judge between which beacon, have one beacon output ir at 38khz so only a 38khz reciever module can see it, if it can't but the light is there, it means it is looking at beacon A, if the module can see it, it means the robot is looking at beacon B

I would use Sharp IR distance sensors for obstacle avoidance.
I would use the beacons on the same frequency (say 38kHz), but transmitting different code, with a delay between them. There are several ways to do this.

This way the robot can detremine the location of each beacon by the code received. If you have 3 beacons you can triangulate the position of the robot in the field.


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