iRobot releases Terra, a robot lawnmower

Back in 2015 it was in the news that iRobot was asking the FCC about using wireless radio technology to position a robot outdoors, but it looks like it took a few more years to see it come to fruition!

From my (minimal) experience with ultra wide band radios the main downsides were that it was relatively expensive for consumer devices, it was less accurate through objects (like a house), and you need a few beacons to get true XYZ position.

I wonder what other sensors the robot uses as well. The outside is a tough environment for consumer robotics, especially something that can be wet and messy like cutting grass.