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Side view of robomower

How Do Robot Lawn Mowers Work?

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These days, it is hardly surprising to find out a robot can take care of your least favorite household chore. Every year, the robotic revolution seems to accelerate and impress us with feats of automation we never thought possible. As a result of the technology being so ubiquitous, we have come to expect a great deal from it.

The trusty robot lawnmower is a good example of this. As an automated gadget, it doesn’t really work in half measures. It can’t just look cool or perform a nifty trick or two because its value depends on it being easier to use than a manual mower (see our article about the best self automated lawn mowers). Unlike a drone or Amazon’s Alexa, it has only got one job. So, it needs to do it expertly.

This guide to robot lawnmowers explains the truth behind the tech and asks whether you should get one for your lawn.

Back of a robot mowerHow Do Robot Lawnmowers Work?

Robot lawnmowers function by generating and interpreting digital maps of a home’s lawn. Most require just one calibration session during setup to create a reference guide of the yard’s square footage, perimeters, and any obstacles such as shrubs or trees. After this is done, the user no longer needs to press buttons, adjust settings, or even switch the lawnmower on. It is fully autonomous.

Once you’ve given it the setup data it needs, it can go about life as any good robot should (with no intervention). Robot lawnmowers can turn themselves on and cut the grass according to a predetermined schedule. This could be a schedule of your choosing or, even more impressively, an ad hoc schedule depending on the week’s weather forecast.

Not all robot lawnmowers have this function but most newer models can connect to the internet, check the forecast and determine if it’s a good day for mowing. If conditions are suitable (warm and/or dry), they switch on automatically and start a fresh mowing cycle. The lawnmower returns to its dock for charging afterward without needing any assistance from the user.

Obstacles are never a problem because the mower has a preloaded map of the space. It knows exactly where to expect them and can swerve, turn, or reverse accordingly. One downside of older robotic mowers is they can only avoid stationary objects that feature on preloaded maps. If you were to move a deckchair for example, an older model may not be able to account for this because it expects to meet it in one position and one position only.

The good news is contemporary models are growing more sophisticated. Some can now detect obstacles more intuitively. They use a combination of preloaded maps and intelligent sensors to predict the position of objects on the lawn and detect unexpected obstacles that are not included on their map. Think of the way an indoor Roomba uses sensors to detect objects present in its floorspace so it can move in a different, safer direction.

Setting Up Your Robot Lawnmower

Robot lawn mower dockedProvided the robotic lawnmower is set up correctly, there is a good chance no further interaction will be needed at least until the lawn changes shape or you decide to upgrade to another device. So, while the setup can be time-consuming, you only need to do it once.

The first step is to install a boundary wire around your lawn. This is a thin cable – it looks a little like the pull cord for a manual mower – and it tells your robot lawnmower when to stop. It is especially important; without this cable, the machine may wander beyond its boundaries and leave the grass. You do not want this to happen particularly on gravel or any stony surface capable of stressing the blades.

The boundary wire also helps to orient the robot lawnmower. When it is finished cutting the grass, it searches for the nearest boundary and uses this to determine the best way back to its charging dock. The wire should be easy to install. Most devices use pegs to create a thin and inconspicuous wire border around the lawn. Some of the higher-priced robot lawnmowers come with installation included. Depending on how much you’re willing to pay, you could have a technician come to your home and lay the boundary wire underneath the grass, so it’s completely hidden.

The boundary wire leads right back to the charging dock so make sure there are no trip hazards. Whichever lawnmower model you choose to buy, there should be plenty of wire to stretch around the garden. However, it is always best to take your own measurements and check these against a models’ specifications before you buy it.

Once the boundary wire is safely set up, the last step is to program the lawnmower. This usually includes inputting the date, time and how often you want the lawn to be cut. If your device has an automated cycle, you can tell it to mow the lawn (without prompting) only on specified days or in certain weather conditions. Read this article for additional tips on setting up a robotic lawn mower for the first time.

The Final Word on Robot Lawnmowers

The top-rated robot lawnmowers on the market are already impressive machines and the technology is improving all the time. While they do have limitations – only a few of the most expensive machines can cut grass in wet conditions – they require minimal interaction and can take over manual mowing with almost no effort.