BEDFORD, Mass. — Robot vacuums have now been around long enough that you might watch one bump around a living room and think, why isn't there a robot that could mow my lawn? Turns out, it's not for lack of trying.


"Honestly, this robot drove me insane," said iRobot CEO Colin Angle after showing off Terra, the company's long-awaited first lawn mower. "It has been an obsession."

The flat square autonomous grass-cutter that Angle's company is unveiling Wednesday resulted from a protracted engineering struggle that included dead-end experiments and a conflict with radio astronomers.

Angle and his colleagues have been fielding the question, "So, when are you going to mow my lawn?" since the company starting selling Roombas in 2002. But teaching a robot to navigate a typical American yard without destroying its flowerbeds was harder than it first seemed. "There was a lot of despair and frustration on the journey," Angle said.

Engineers threw every technology and mechanical design they could at the secret project, which they hid behind tall, opaque fences abutting a freeway just outside iRobot's Massachusetts headquarters. The test lawn included a picnic table and other obstacles.

The first problem was helping the robot identify its location so it wouldn't get lost and miss spots. Satellite-based GPS technology didn't do the trick; it was too "finicky" because interference from tree branches or nearby houses could render it useless, Angle said.

Also ineffective was the sophisticated computer vision that powers the latest Roombas. The technology didn't work well outside because camera lenses can get blocked by leaves or dirt, and its machine-learning algorithms get confused as the mower bumps up and down. Laser range-finders and ground-based beacons presented different challenges.

The company made so many attempts that several early lawnbot prototypes can be spotted in the 2008 heist film "21." They make their appearance in a scene where Angle plays a professor at the Massachusetts Institute of Technology announcing the winner of a robotics competition. The current Terra looks nothing like those prototypes.

"We had given up," Angle said of the project. "We probably gave up twice."

Ultimately, though, financial pressure on the robot maker to diversify its product lineup raised the stakes. (After spinning off its defense robotics division in 2016, iRobot is almost exclusively a seller of vacuums. The main exception is the Braava robotic mop, which accounts for a fraction of total revenue.)

Robotic lawn mowers also started to proliferate in Europe, where they're now a roughly $300 million industry. Those robo-mowers, however, require homeowners to set up a perimeter of boundary wires to keep the machines in a confined area.


The company finally found its answer in a radio technology based on "ultra-wide" bandwidths that would guide the mowers with the help of beacons situated around the lawn, combined with the map-making memory that iRobot already uses for its vacuums. But that idea ran afoul of astronomers who said the radio signals could interfere with their studies of interstellar chemistry.


