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pradeep
pradeep • Aug 4, 2006

IR Sensors

IR sensor!!

hey,
can anyone over here share their idea regarding how IR sensors r used in robotics!!:smile:
Kaustubh Katdare
Kaustubh Katdare • Aug 4, 2006
Pradeep, feel free to start a new thread for the topic. 😀

Edit:(New thread created.)
pradypop
pradypop • Aug 4, 2006
Hi pradeep, we share the name and trade. I did develop a small buggy using IR sensors a few years back. IR is detected by its reflection from the objects in its path. But one big issue with IR is its omni-present. So its difficult to distinguish between the IR which got reflected from our source and IR which is present around.

So to solve this issue, we use IR sensors and receivers which toggle between on and off states at certain rate. There are standard transmitters and sensors available off the shelf which toggle at the rate of 38khz, 40khz....So an IR signal oscillating at 38Khz(generated by 38Khz Tx when its supplied with 5v) is sensed by a 38Khz receiver(which is a transistor whose base is IR sensitive. This transistor enters saturation upon IR incidence). You can connect this IR sensor to interrupt pin of your controller to generate interrupt when IR is detected...

You can have varying IR frequencies representing various events. Even TV remote is built on same principles. Each button has a certain fixed frequency IR. That's how numbers are identified...
pradeep
pradeep • Aug 4, 2006
some more!!

hey,
thanx for ur reply on this.
but am doing a line following robot.
in this we will be having both transmitter and receiver pointing the same direction.
actually the receiver works like a photo diode.i.e., its resistance decreases as ir rays r incident upon it.
but when i try to implement it practically,am not geting much decrease in the resistance.
so can u plz help me to debug this issue??
pradypop
pradypop • Aug 4, 2006
I think your robot follows black lines. Black objects completely absorb IR. So you need to have your sensor and source quiet close to each other. When you are off line you'll get IR reflection and when you are on line no reflection. Is this your design?

Is there atleast a small voltage drop across sensor when IR is incident upon it? If thats the case than you can use an op-amp based comparator to solve the bug. Here the reference voltage is going to be the voltage when there is no IR incident upon the sensor....
pradeep
pradeep • Aug 4, 2006
hey !!

the principle u have mentioned is exactly the same which i am implementing.
i do get a very small voltage drop when i tested it with a tv remote.
drop from 5V to 4.97V.that is too low for an op-Amp to be used i guess!..
can u give me suggestions based upon this??😒
pradypop
pradypop • Aug 4, 2006
You shouldnt be using a TV remote. The sensor which you are using measures senses average of the signal strength which is too low for an oscillating signal like that of a TV remote. You should be using an IR LED for your testing where you should be placing your sensor and source in a black cylinder where only the other side of the cylinder will be open. Now power on the LED(its actually a transistor). If other side is covered by a shiny non-black surface(mirror at experimental stages would be great) then you have least resistance and least possible voltage. And when open surface is closed with a black porus surface you'll get higest resistance and highest possible voltage. Just experiment with this setup and letme know. If it still doesnt work than you might need to change youe sensor.
pradeep
pradeep • Aug 5, 2006
thank u prady,
ill try with this kinda setup and get back to ya!!
turn2me6
turn2me6 • Sep 16, 2006
They may be used for controlling ur Robotic m/c (in remote control device)or otherwise if ur giving that kinnof intelligence to the Robot that it can sense obstacles in between its path, then its used for sensing the obstacles.
May be there might be some more uses of IR sensors but these are the two basic uses as known to me..

😁
muzaffar
muzaffar • Feb 24, 2007
Re: IR sensor!!

pradeep
hey,
can anyone over here share their idea regarding how IR sensors r used in robotics!!:smile:
------------------------------------------------------------
hello,
IR sensors are mostly used in robotics items, this are connected at the reciever section .the output of the antenna are fed to sensor which will inturn fed to relay to energize.as per the relay energize(driver circuit) we can move the motor this all depends upon transmitting programe.and the robot moves.
thank you.😁
pchaubal89
pchaubal89 • May 1, 2009
IR Sensor Array

Hi
I would like to know about an ir sensor array that can give an output signal corresponding to the position of an ir object above it.
For eg.
If i place my hand above it, it should give me a unique signal as to where my hand is positioned with respect to it. Also i would like to know if its range can be altered.
Rifaa
Rifaa • May 1, 2009
to pchaubal89, if this is your first post then please introduce your self and start a new thread concerning your problem in the appropriate section. that way you'll get more replies, and be explain more about your project then only CE's can help.
Regards
Rifaa

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