If you have a Roomba, you know they are handy. However, they do have a habit of getting into places you’d rather they avoid. You can get virtual walls which are just little IR beacons, but it is certainly possible to roll your own. That’s what [MKme] did and it was surprisingly simple, although it could be the springboard to something more complicated. You can see a video about the build below.
As Arduino projects go, this could hardly be more simple. An IR LED, a resistor and a handfull of code that calls into an IR remote library. If that’s all you wanted, the Arduino is a bit overkill, although it is certainly easy enough and cheap.