Electronics > Electronics

IR detector

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zs:
You guys have been great help, Thanks. Do you mind telling me a couple of ways how to make the beacons transmit different code? One more thing, I'm thinking of building the beacon myself, but are there beacons in the market that transmit IR in omni-directional? I really appreciate your help.   

zs:
Hi,
Hence no one answered my previous question, I have another one. How can I direct my Robot to the 1st IR Beacon while avoiding obstacles on the way? I want my Robot to know where its 1st destination is when it start moving and detect IR light from the 1st beacon. Any Idea how to execute this task? Help my Robot so that it can get to its destination safely  :). Thanks

Ro-Bot-X:
The beacons can be made using a microcontroller that sends serial data using IR, over a carrier frequency like 38 or 40 kHz. One beacon will have the electronics on board and the others will be connected by wires. Or, if you need them to be wireless, you will need each beacon to have it's own microcontroller, IR emitter and a receiver. When you power them up, the first one will start to "beep" in IR a message, let's say 100, every 30 ms. The second beacon will listen for message 100 and after it receives it, will wait 10ms and send i's own message, let's say 150. The third beacon will listen for the message 150 and after iit receives it, will wait 10 ms and send it's own message, let's say 200. The emitter can be an array (circle) of IR LEDs connected to a transistor, connected to the microcontroller. This way the signal will go in each direction. The robot will have the receiver mounted on a servo to be able to scan the area in front of him to find the first beacon (will listen for message 100) then drive to it, using the Sharp distance sensors (wich don't interfere with the IR messages) to go around obstacels. Each time an obstacle has been bypassed, the robot will scan for the beacon again, to make sure it has the corect heading. After arriving at the first beacon, it will scan for the second beacon (listening for message 150) and drive towards it and so on.

zs:
I like the idea of mounting the IR detector on the servo to search the IR beacon, but how does the robot knows if the beacon is on the right, left or in the front? There gotta be some way to determin the location of the robot relative to the beacon or vice versa. Any idea? Thanks.

Admin:

--- Quote ---I have another one. How can I direct my Robot to the 1st IR Beacon while avoiding obstacles on the way?
--- End quote ---
Remember that the objects cannot block line of sight between the robot and beacon - IR can't pass through most objects.

I plan to write up a pathfinding tutorial sometime this summer so your robot can go through mazes and do mapping and object avoidance, etc.

The simplest way to go around an object:
Step 1 - robot goes toward beacon
Step 2 - robot comes into contact with blocking object
Step 3 - robot swaps to wall following algorithm
Step 4 - robot follows wall of object until no object is between robot and beacon
Step 5 - go to Step 1

This algorithm is far from being efficient or flawless, but its the easiest possible and best for a beginner to start off with.

Good luck!
John

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