Robot Mowers Are Actually Good Now

Photography: Simon Hill

Light Detection and Ranging (Lidar): This system, also used by self-driving cars, emits rapid laser pulses to map the terrain in 3D. It allows mowers to cut grass under thick tree canopies or near tall buildings where GPS signals typically fail.

AI Vision: Some mowers now use cameras to recognize lawn areas, edges and obstacles. Robot lawn mowers with AI vision can potentially avoid footballs, cats, other creatures, and perhaps even pet messes. But they can also be overly sensitive, pausing for fallen branches, leaves or overhanging plants.

Some of the best mowers, like the Mammotion I’m currently testing, use a combination of the latter three technologies to map and cut areas precisely, navigate reliably to and from the charging base, and avoid unexpected obstacles. None of them are infallible. My first choice chewed up a deflated wading pool, but if you set the sensitivity too high, they leave areas uncut.

In addition to finding their way, many of the newest robot lawn mowers are designed to handle rough terrain. Not too rough, but perfect for a bumpy garden or yard with steep slopes. Some models even come with interchangeable tires, allowing you to use grippier wheels when you need them. But it’s important to check the terrain and slopes your mower can handle up front. Four-wheel drive or all-wheel drive mowers are best for handling steep or uneven terrain.

The avant-garde

Traditionally, robot lawn mowers were terrible at cutting right to the edge of your lawn. Most of the early robot mowers I tested left a thick edge of uncut grass, up to 1 foot wide. I don’t think this problem is entirely resolved, but some newer models have offset blades that sit closer to the edge of the machine, or they have an overhanging section that extends beyond the wheels, so that it can cut right up to the edge when the robot lawn mower turns. There are even robot lawn mowers with integrated mowers and other gardening tools, although I haven’t tested any yet.

Even though edging is improving, I still find that most robot lawn mowers need some adjustment to reliably mow the entire lawn. I often have to edit the map or adjust the sensitivity to make sure they cut all the way to the edge, but there are still areas that seem to be missing. Overhanging plants, shrubs and trees cause problems, as robot lawn mowers naturally exercise caution when dealing with potential obstacles. There is still room for improvement here.

Smart finishing

Husqvarna app via Simon Hill

While the first robot mower I tested made my lawn muddy, most robot mowers now have some form of rain sensing, so you can set them to not cut if the grass is wet. The latest models are also much better at handling wet grass and turning without skidding or upsetting a large portion of your lawn.

Some robot lawn mowers offer customization in terms of your desired lawn finish. You can find an option in the app for Wimbledon Stripes (dark and light stripes), made by mowing rows in opposite directions. Some clippers can even create spirals, checkerboards, and other patterns.