shielding an IR sensor

Projects General Guidance
1

I want to build a docking station for a Dirt Devil robot that has undergone lobotomy and now has an Arduino inserted. For the station I have an IR led and the idea is that the robot turns around its axis until it detects the IR signal and then homes in on it.

Problem is that the keyes IR sensor seems to detect the IR signal all around it. I even put the sensor inside a copper tube open at one end, but still it detects an IR source held next to the tube.

Question: how do I shield the IR sensor in all directions except at the front?

Paai

2

The usual way is to add modulation to the IR source (LED) and have the receiver only respond to the IR that is at the modulation frequency. Like an IR receiver/decoder for IR remotes works.

3

groundFungus:
The usual way is to add modulation to the IR source (LED) and have the receiver only respond to the IR that is at the modulation frequency. Like an IR receiver/decoder for IR remotes works.

There is only one IR source in the room, so the receiver has no alternatives to choose between. I just want the receiver to recognize the signal only when in front of the robot.

Paai

4

A tube around the sensor. The longer and narrower, the more targeted it will be.

5

wvmarle:
A tube around the sensor. The longer and narrower, the more targeted it will be.

As I said in my original post: "I even put the sensor inside a copper tube (15 cm) open at one end, but still it detects an IR source held next to the tube."

I have been searching Google this afternoon, but it seems nothing is written about this particular problem. Strange, because the idea is obvious: shield the IR sensor in all directions except one and then make the robot do a turn until the sensor is activated...

6

The maybe the IR signal is too strong at the receiver and there is no linear response, it is saturated. Please post photos and details before continuing on with this...

7

might sound stupid, but painting the tube black might help.

at least thats what i see others do for their maze solving robot. and use a normal tube. copper reflects light, which might be the cause of ur problem

8

tzijie:
which might be the cause of ur problem

It's an IR problem.

Or did you mean "your"?
If so, why didn't you type "your"? Would that really be so much extra effort?

9

AWOL:
It's an IR problem.

Or did you mean "your"?
If so, why didn't you type "your"? Would that really be so much extra effort?

yes, i meant "your".

IR gets reflected off different mediums differently. its essentially red light.

different reflective surfaces reads different voltage/readings too.

for example, glossy black and matte black easily has about 20 value difference when you use analogRead()

edit: messed up the quote tags lol. fixed it.

10

Please be careful when you use quotes - I didn't write much of what you attributed to me.

its essentially red light.

No, it's essentially infra-red light. Near infra-red more than likely.

11

A shiny copper tube may very well reflect IR indeed. I was thinking of PVC or so. Non-reflective, and most plastics absorb IR - even optically clear plastics tend to be opaque to IR.

12

At this moment I find that adding some layers of tape over the IR LED and putting the sensor in a PVC tube seems to give enough directional information. Haven't tested it in real life yet.

Thanks for thinking with me.