From Slate magazine: Someone thought it would be a good idea to equip a robot with rapidly spinning metal blades! Meet the LawnBott LB3500.
No doubt the LawnBott T-1000 will mow your lawn using a fracking laser beam! 
It can’t be bargained with . . it can’t be reasoned with . . . it doesn’t know pity, or remorse, or fear, or pain . . . and it absolutely . . . will . . . not . . . stop until your lawn in mowed ! !
It looks like a wireless vacuum cleaner to me. Bet it’d fail to handle my kikuyu grass, tho’.
None of these lawn mowers can do a hill or slope so they’re useless in most of Wisconsin.
Oh, great – a Roomba for your lawn. If it sucks up a rock and the blades get jammed, will it sit outside your house making a forlorn “dooDOO! dooDOO!” noise until the neighbors call the cops and report you for robot abuse?
Not that I’m saying that my neighbors have ever reported me when I’ve been bored and tortured my Roomba. Nope. Never.
So Judgment Day will come sometime after the merger of Kyodo America and WOLF-Garten? “Kyodo-WOLF”…that sounds reasonably Weyland-Yutani-ish.
I swear I saw a similar product adverstised years ago, even earlier than the roomba.
There used to be a robot store locally. (Yes, their business was selling robots, mostly toys, and “scientific” kits for students. For some reason they went under…) One of the few allegedly “useful” robots they sold was a robotic lawnmower. Unlike this one, or the Roomba, it worked on an inertial navigation system - the owner would have to walk the robot along the perimeter of the space to be mowed, and then let it get to work. This was back in the mid-to-late nineties, and may be what you’re remembering.