Robot lawnmowers have reached a turning point. After years of boundary wires and hesitant navigation, this summer’s crop of autonomous mowers can handle complex yards with surprising skill. But they are not yet perfect. With some oversight, however, they can take a major chore off your hands.

I spent three months testing five robot mowers on my flat, three-quarter-acre property in coastal South Carolina. The landscape is tricky: sandy soil, centipede grass, lots of trees, and patchy GPS coverage. In past years, many mowers failed here, getting stuck under oak trees or losing their way completely. This year, things went much better. Huge improvements in navigation and maneuverability meant the mowers stopped getting stuck. My lawn has never looked better, and my spouse, who had sworn off robot mowers after a user-error incident, is now a convert. His riding mower has been idle for over a month.

What’s better this year

The key upgrades are network RTK navigation, fallback navigation systems, and improved all-wheel-drive. RTK — real-time kinematic positioning — is a satellite technology that provides location data accurate down to a centimeter or two. It uses stationary ground stations along with GPS. Most mowers today use RTK, ditching the boundary wires of older models. However, standard RTK requires a clear view of the sky, which trees and buildings can block. That’s where network RTK, or NetRTK, comes in. It taps into a network of existing reference stations through a cloud connection, so you don’t need to install an antenna. Most of the mowers I tested worked out of the box using NetRTK, though coverage varies by location.

The new mowers also use secondary navigation systems like lidar or vSLAM to keep them on track when the satellite signal drops. This combination of technologies, plus bigger and more capable machines, meant I no longer spent my summer dragging confused mowers out from under oak trees. The consistency of modern robot mowers is impressive. Running daily and shaving just millimeters at a time, they created a noticeably lusher lawn. I walked on it barefoot this morning, something I’ve never done before. They work quietly around the clock without bothering pets, wildlife, or neighbors. And the professional-looking lawn lines they make are a bonus.

What still needs work

Despite these improvements, robot mowers are far from perfect. These are autonomous machines with blades, and leaving them to their own devices comes with risks. In my testing, one mower spent three days methodically destroying a patch of lawn before I noticed. Another took out two outdoor extension cords. Several models dug sandpits in bare patches, and one tried to climb a small tree.

Obstacle detection is better across the board, but it still has a long way to go. Hoses, cables, and cars are still challenges. My family now knows to check under the wheels before driving away. Gates remain unsolved, too. I still have to manually open mine to let the mower access the full property. And while every manufacturer currently advertises NetRTK coverage as free for the lifetime of the device, relying on a cloud service to mow your lawn has obvious downsides. Finally, robot mowers are still expensive, and long-term durability is a concern.

The best robot mower I tested

The Segway Navimow X430 is by far the best mower I tested. This 60-pound beast looks like Darth Vader’s dog and was the only mower that didn’t get stuck once. Its 4WD wheels and impressive suspension rolled through potholes, over sticks and rocks, and even small tree branches. It navigated around my chickens and across the tall, uneven transition from the front to back yard. It was the only bot that could mow both areas in one trip, as long as the gate was open.

The X430 uses a combination of RTK, vSLAM, and vision-based tech to navigate. It covered my entire property without once getting lost or stuck. Its zero-turn maneuverability let it pivot smoothly without damaging the lawn. The dual-disc, 17-inch cutting width covers more ground, and it mowed most of my backyard in under three hours, nearly twice as fast as most competitors. I also liked the remote-control mowing feature, which was handy for tidying up edges and sensitive areas like flower beds.

The trade-offs: Its speed means a few blades of grass go untrimmed. Its rain sensing relies on internet weather data, which meant it often skipped mowing because it predicted rain that never came. Setting up NetRTK was a bit tricky, mostly because the charging station needed a clear view of the sky, requiring an awkward placement away from the house.

A great lidar-based alternative

If you can’t rely on RTK, the Dreame A3 AWD Pro 2500 is the best option. Its lidar and camera-based navigation performed nearly as well as the Segway in my backyard, only getting stuck a couple of times. It doesn’t need a clear view of the sky, so you can place it anywhere. Its sliding edge-cutting deck worked slightly better than the Segway’s EdgeSense feature. But lidar was the least reliable navigation technology in my testing. Sometimes the A3 declared the job complete when it wasn’t, and lidar robots do best in fenced-in yards, as they can more easily get lost and wander off into a neighbor’s property.

The Dreame rarely got stuck, but its turning mechanism wasn’t as smooth as the Segway’s, and it dug several sandpits in bare areas. I do like its Garden Guardian mode, which uses the camera as a roaming security guard. It can also identify when people cross its path and warn them it’s working. It was amusing watching it surprise dog walkers passing by the front yard.

An expensive but reliable option for open yards

Husqvarna’s Automower 420 IQ is a good option for a standard, treeless yard. It has the longest warranty (four years), the easiest app and controls, and a modular design for longevity. It’s 2WD, but its large wheels tackle uneven terrain well. It requires an RTK antenna and has the option of cloud-based RTK in some areas. However, its backup navigation for satellite dead spots requires installing physical boundary wire.

I tested this mower in my neighbor’s yard, which has fewer trees and clearer sky views. It navigated well, but it uses radar for obstacle detection and has no camera. This meant it wasn’t as good at dodging objects as the others, running into bushes once and trying to climb a small tree. But for a large, uncomplicated yard, it’s a solid choice thanks to Husqvarna’s broad support network, free-for-life cellular connectivity for theft and NetRTK, and impressive performance.

Navigation combo, but software issues

The Mammotion Luba 3 AWD 3000 combines all three wireless navigation types — RTK, lidar, and vision — making it ideal for properties with spotty GPS coverage like mine. But it’s less nimble than the other AWD models due to lower ground clearance and weaker suspension. Its turning mechanism tore up a couple of areas in my garden, particularly a shaded, damp spot. Mammotion acknowledged the issue, saying a recent update to turning logic caused unwanted results, and deployed software updates to address it. But relying on software updates to fix fundamental problems with an expensive mower is a concern.

A budget option for smaller yards

The Roborock RockNeo Q110H is my budget pick. This rear-wheel-drive mower was impressive on my flat, treed front yard, though its lack of all-wheel-drive meant that occasional large tree roots stopped it in its tracks. That, and its more limited range, is why it’s half the price of the others. It offers RTK and vSLAM navigation, with the option of an antenna or NetRTK. It’s remarkably similar to a model I tested last year, but with upgrades including better camera-based obstacle detection, steeper slope navigation, and a wider cutting blade. It also has remote-control mowing and a built-in edge-cutting feature, with the option of an add-on module.

Edge cutting remains a work in progress for all mowers. Some do well straddling the edge, but if you have a fence or delicate boundary, that won’t work. Companies are trying various solutions, including special attachments. One model with a side-mounted string trimmer looks promising, but for now, plan to keep your manual trimmer handy.

Robot mowers have improved significantly over the last 18 months. Advances in navigation have solved many of the pain points from previous testing, and bigger, beefier bots are better at handling the varied terrain of American yards. Today, the right bot will maintain your yard beautifully with minimal effort. They still need oversight and the occasional rescue, and they haven’t solved every problem, but they do take a lot of the work out of maintaining your lawn.

Source: The Verge News