Robot lawnmowers have finally become good enough to take a significant amount of work out of maintaining a yard. But they are not yet set-and-forget machines. If you do not want these autonomous cutting machines to tear up your lawn or wander into a neighbor's property, you will still need to keep a watchful eye. With some oversight, however, they can turn a dreaded chore into a background task.

How the test was run

This summer, five robot mowers were tested on a flat, three-quarter-acre property in coastal South Carolina. The landscape featured sandy soil, centipede grass, and plenty of trees. The conditions were deliberately harsh, because that is where many robot mowers have failed in the past. The improvements in navigation and maneuverability were immediately noticeable. None of the bots spent hours stuck under an oak tree or digging themselves into a rut. In fact, my lawn has never looked better. A spouse who previously swore off robot lawnmowers after a user-error injury has become a convert, and the riding mower has been sitting idle for over a month.

The consistency of robot mowers is impressive. Running daily and trimming only millimeters at a time, these machines created a noticeably lusher lawn. Walking barefoot on the grass was something I had never done before. The mowers work quietly around the clock without disturbing pets, wildlife, or neighbors. The professional-looking lawn lines are an added bonus.

What has gotten better

The key upgrades this year are network RTK navigation, fallback navigation systems, and improved all-wheel-drive for tackling rougher terrain. RTK, or real-time kinematic positioning, is the satellite positioning technology that most automowers have adopted over the last few years as they moved away from boundary wires. It uses stationary ground-based reference stations and GPS to provide positioning data accurate to a centimeter or two. It is the same technology used in surveying and drone navigation.

Every mower tested, apart from the lidar-based Dreame, comes with its own RTK antenna that needs to be installed in the yard with a clear view of the sky. Trees, a neighbor's house, or even the roofline can block the signal. In previous testing, not a single RTK mower ran successfully in my backyard because of spotty GPS coverage. This time, however, all the new models offered NetRTK as an option. NetRTK taps into a network of existing RTK reference stations through a cloud connection and requires a Wi-Fi or 4G connection on the mower. Most worked out of the box without installing the antenna, though coverage varies by region.

RTK mowers now also use secondary navigation technology such as lidar or vSLAM to stay on track when the satellite signal drops. This improvement, combined with larger and more capable machines, means I no longer spent the summer dragging confused mowers out from under trees.

What still needs work

Automowers are far from perfect. These are autonomous machines with spinning blades, and leaving them unattended carries risks. In testing, one mower spent three days methodically destroying a patch of lawn before being noticed. Another chewed through two outdoor extension cords. Several models dug sandpits in bare patches, and one tried to climb a small tree. Obstacle detection has improved across the board, but hoses, cables, and cars are still challenges. My family now knows to check under the wheels before driving away.

Gates remain unsolved. I still had to manually open a gate to let the mower cut the full property. Also, every manufacturer currently advertises NetRTK coverage as free for the life of the device, but relying on a cloud service to mow your lawn has obvious downsides. Automowers are still expensive, and long-term durability is an open question.

The best robot lawnmower overall

Segway Navimow X430

The Segway Navimow X430, priced at $2,499, is by far the best mower tested. This 60-pound machine looks like a miniature armored vehicle and was the only mower that did not get stuck even once. Its 4WD wheels and impressive suspension rolled through potholes, over sticks and rocks, and even over small tree branches. It navigated around chickens and across the tall, uneven transition between the front and back yards. It was the only bot that could mow both areas in a single trip with the gate open.

The Segway uses a combination of RTK, vSLAM, and vision-based technology to navigate. It covered the entire property without getting lost. Its zero-turn maneuverability lets it pivot smoothly without damaging the grass. The dual-disc, 17-inch cutting width covers more ground, allowing it to finish most of the backyard in under three hours. That is nearly twice as fast as most competitors. The remote-control mowing feature was handy for tidying up edges and sensitive areas around flower beds.

The speed does mean a few blades get left untrimmed. Its rain sensing relies on weather data from the internet, which sometimes prevented mowing because rain was predicted but never arrived. Setting up NetRTK was a bit tricky because the charging station had to be placed in an awkward spot with a clear view of the sky, and it could not sit under an awning or against a building.

Best lidar-based alternative

Dreame A3 AWD Pro 2500

The Dreame A3 AWD Pro 2500, priced at $3,099.99, is the best option if you cannot rely on RTK. Its lidar and camera-based navigation performed nearly as well as the Segway in my backyard, only getting stuck a couple of times. It does not 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 edge feature in testing. Be aware that it has a fixed minimum cutting height of 1.2 inches.

Lidar was the least reliable navigation technology in my testing. The A3 sometimes declared the job complete when it was not. Lidar robots do best in a fenced yard because they can become disoriented and wander into a neighbor's property. That never happened with the RTK robots. While the Dreame rarely got stuck, its turning mechanism was not as smooth as the Segway's, and it dug several sandpits in bare spots. The optional Garden Guardian mode uses the camera as a roaming security guard and can warn people crossing its path that it is working.

Best for large, open yards

Husqvarna Automower 420 IQ

The Husqvarna Automower 420 IQ, priced at $3,299, is a good option for a standard yard. It has the longest warranty at four years, the easiest app and controls, and a modular design for longevity. It is 2WD, but its large wheels handled uneven terrain well. It requires an RTK antenna and offers optional cloud-based RTK in some areas. Its backup navigation for satellite dead spots requires installing physical boundary wire, which is a downside for those who want a wire-free setup.

In testing at a neighbor's yard with clearer skies, it navigated well. But it uses radar for obstacle detection and has no camera. It was not as good at dodging objects as the others. It ran into bushes once and tried to climb a small tree. For a large, uncomplicated, tree-free yard, it is a solid choice thanks to Husqvarna's broad support network, free-for-life cellular connectivity for theft and NetRTK, and impressive overall performance.

A capable mower with a turning issue

Mammotion Luba 3 AWD 3000

The Mammotion Luba 3 AWD 3000, priced at $2,799, combines all three wireless navigation types: RTK, lidar, and vision. That makes it ideal for properties with spotty GPS coverage. But it is less nimble than the other AWD models because of lower ground clearance and weaker suspension. Its turning mechanism tore up a couple of areas in the garden, especially a shaded spot near a neighbor's sprinklers that stayed damper than the rest. Mammotion acknowledged the issue and said a recent update to the turning logic caused the problem. They have deployed several software updates to address it, but relying on software updates to fix fundamental problems with an expensive lawnmower is a concern.

Budget pick for smaller yards

Roborock RockNeo Q110H

The Roborock RockNeo Q110H, priced at $1,299, is the budget pick. This rear-wheel-drive mower was impressive on a flat, treed front yard, although its lack of all-wheel-drive meant the occasional large tree root stopped it in its tracks. It offers RTK and vSLAM navigation with the option of antenna or NetRTK. It is remarkably similar to the Segway Navimow i100N from last year, but with better camera-based obstacle detection, steeper slope navigation, and a wider cutting blade. It also has a built-in edge-cutting feature and supports manual remote-control mowing.

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 will not work. Companies are trying various solutions, including special attachments. For now, you should 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 main pain points from earlier testing, and bigger, beefier bots are now better at navigating the varied terrain of American yards. The right robot will maintain your yard beautifully with minimal effort. They still need oversight and the occasional rescue, and they have not solved every problem, but they do take a lot of the work out of maintaining your yard.

Source:The Verge News