Robotic lawn mowers are going to be the next life-style changing appliance in America. Think about it, how many times have you wanted to get away for the weekend or go to some event but yard work kept you tied to the house? I can't tell you how many golf outings I have missed.
Robotic lawn mowers can mow the yard, go back to the charger, and go back out again on their own without human intervention. This is a large step forward from only two or three years ago.
Residential robotic lawn mowers run on batteries, so they don't use gas or oil. They are pretty much maintenance free except for the occasional replacement of the blades. They waterproof and they don't rust.
A perimeter wire, like an invisible dog fence is placed around the yard to define the mowing area. Gardens, flowerbeds and trees can also be easily protected. Running the wire is not difficult, you can DIY or have it professionally installed. The wire can be buried up to 2 inches deep.
The robotic mowers must sense the presence of the wire around them. If the mower should somehow go past the boundary it will immediately shutdown, so you don't have to worry about it running down the street (unlike your dog).
You can set the time for them to mow. Since they are quiet and don't need to see the yard, they can be allowed run at night while everyone is in the house or even asleep. On schedule they will depart from the charger and start to mow. When they run over the wire or into an object they will turn and go another direction. Some mowers use a random pattern while others go back and forth. When the battery gets low they find the perimeter wire and follow it back to the charger. All robotic mowers on the market today do a very good job covering the yard and not leaving uncut patches.
Ensure that the robotic mower you are interested in goes back to the charger on its own the added expense will be worth it. A rain sensor is a must-have as well, some robotic mowers are heavy and can get stuck in soft areas.
Robotic lawn mowers are now useful and practical. They are still an oddity, so if you get one expect the neighbors to come from blocks around to watch it work.