Let's Make Robots!

IR compound eye

Mr._General_4.bas17.21 KB
Vendor's Description: 

I have posted some tip/walkthroughs on home made IR sensors for obstacle detection and later for motion tracking. Now DAGU proudly presents the IR compound eye. Designed to fit LMR's universal sensor bracket, this sensor works by shinning IR light onto an object and then tracking the reflected IR. This sensor does not work in bright daylight as sunlight has a lot of IR and blinds the sensor.The IR LEDs can be controlled by a digital output so that ambiant light as well as reflected light can be measured. Your microcontroller needs 4 analog inputs available to use this sensor. See a video of it working here: http://www.youtube.com/watch?v=iKYCob7getU

Note: calibration is not normally required, heatshrink is provided fo those who wish to fine tune their eye. A black permanent marker can also be used. Incorrect application can reduce the range of the eye.

This product is now sold at Robot Shop.

Click on the schematic for a bigger image.



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Just bought three OddBot IR Compound Eyes from Yourduino. Can't wait until they arrive!

I just purchased a Mr. General and soldered the IR compound eye.  When I put the output pin high, I can see (viewing through my digital camera) the IR LEDs turn on. 

However, all four sensor readings are very low.  Using an Arduino to read the sensors, I am getting readings between 0 and ~15 (out of the maximum 1023 10-bit ADC value).  The "high" value is when the piece of paper is right on top of the compound eye board.  So something is definitely wrong.  This is true for all four sensors.  I have double checked the resistor values and they look correct.  When I placed the 8 phototransistors, I put the anode (longer leg) towards the top of the board.  Did I screw up the polarity?  Or perhaps I overheated every single phototransistor (I did try to be careful but am not super-experienced).

I would like to understand the error of my ways, even if this board is a lost cause.

I think I did shoot myself in the foot.  The phototransistor long leg is not the anode (duh).  It is the emitter.  So I did reverse the polarity of all 8 PTs.  Ugh.

I have only my naivety to blame.  I just wish the instructions (Mr. General PDF downloaded from robotshop) had mentioned something about the PT legs.  It would have saved me from my own foolishness.


I'm sorry to hear that. The silk screen on the PCB clearly shows the flat side of the PT.

As this is a common problem I am going to try and change things so that in the future all eyes will be factory soldered and tested. It will cost a little more but it will save a lot of problems in the long run.


I don't mind making it myself -- good practice.  My reversal of the PTs was a useful lesson to make sure I understand what I am doing before I solder.  BTW, I just found the very useful page "Understanding Mr. General".  Thank you.

I'm probably missing something, but I don't see how to buy this. Since it has a price I'm assuming that can be done?



Dagu used to sell these directly to LMR. The are now sold by our distributors. DAGU now has it's own page at Robot Shop. You can find the eye here: http://www.robotshop.com/dagu-compound-infrared-sensor-4.html

I took a look and Robot Shop wants more than it costs for shipping. UPS ground too (they've lost a thing or two for me in the past).

Thanks anyway.




Is there a way to make a sensor like this work in daylight ?



The 5cm range is with the complete setup meaning the servos of the Pan/Tilt kit are moving and activly tracking.

Indeed when I display the values of the eye alone I can see objects from as far as 20+cm but I need to sacrifice some of this to make the tracking more stable. Right now the value of max_dist which is quite conservative and I'm sure that after spending some time with it I can easily increase the detection range. It just needs some more tweaking but I do not want to loose the smoothness of the tracking motion of the servos.