IR sensors horisontal/vertical?

Hi, just need confirmation that I understood correctly:

on sumo robot its better to put the IR sensors vertical + emitter up & sensor down? atleast that is on sensor data sheet http://www.sharp.co.jp/products/device/doc/opto/gp2y0d02yk_e.pdf

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It is not saying that. It says that the orientation relative to target should be as illustrated. It doesn’t matter which is up or down. It is the direction relative to what you want to sense.

It will still work at different orientation to the target but may not be reliable.

Weedpharma

I know that it works in other orientation :) but have someone tested how "not reliable" it is? how to test it? for naked eye the orientation of sensor in the stationary setup when i moved my hand front of the sensor did not make any difference.

"How to test it"?

Use it and try lots of different ways of using it. The manufacturer has said the preferred way. Just try it.

Weedpharma