A Guide to Choosing the Best Robot Lawn Mower
Compiled and Edited by True Experts in Gardening Equipment

WHY SWITCH TO A ROBOT LAWN MOWER?
If you love your garden, you’ve surely asked yourself this question, perhaps whilst browsing through garden care products, looking for a way to save time without having to compromise on a well-tended garden.
This article aims precisely to clear up the doubts typically associated with new technology, so that you can understand the features and how to use robot lawn mowers, even as an alternative to more traditional lawn mowers.

1. The main features of a robot lawn mower

In the field of gardening and lawn care, robot lawn mowers, or garden robots, represent a concentration of technology, the ideal purchase for those with a fairly even lawn and few obstacles. Buying a robot lawn mower can be compared to buying a car, where the associated hi-tech features play an increasingly prominent role, making the robot lawn mower a fully customisable and configurable product tailored to your needs.

First of all, let’s examine the features and benefits of these robots; the first question that comes to mind, especially in the field of automation, is: Do these devices really work?
The answer is yes, so much so that we now have super-efficient robot lawn mowers that not only save us the hassle of mowing the lawn but also make our garden even more welcoming and well-kept than with a traditional mow; the robot, in fact, has a very high cutting efficiency.

• Whilst traditional mowing is carried out seasonally every fortnight or so, requiring the cutting of several centimetres of grass which must then be removed, the robot, by passing over the lawn frequently, cuts just a few millimetres off the grass blades and leaves them on the ground; as these decompose rapidly, they act as a natural fertiliser for the entire treated area.

• A robot lawn mower can cut the grass in a garden using various cutting systems based on different algorithms. In particular, we can divide the cutting systems into those programmed according to a random pattern or those based on the robot’s position (determined by satellite triangulation, as we shall see later). Thanks to both modes, robot lawn mowers are able to cut the entire surface without leaving any patches uncut, resulting in a perfectly even lawn. However, in random programming , the robot may pass over areas where it has already cut the grass several times, leading to inefficiencies in terms of time and energy. Instead, thanks to the satellite triangulation system, the robot is able to recognise the areas where it has cut the grass and those where it has not, ensuring it cuts only where necessary.

• Other frequently asked questions concern energy consumption and noise levels; as it is a battery-powered product, both are very low. In fact, energy consumption is very low—it is estimated to be 1 to 4 times lower than that of a traditional lawn mower (petrol lawn mower or riding-on mower) — without taking into account that the mowing frequency is much higher. With a robot lawn mower, therefore, the result is better at a very low cost.
• It is also important to highlight their environmental benefits: unlike petrol-powered lawn mowers, they produce no pollution whatsoever.

• The electric motor is extremely quiet; it can even be programmed to mow at night without causing any disturbance to you or your neighbours.

2. Choosing the robot best suited to your needs

Before we look at the features that will help us choose one model over another, a preliminary point must be made: the robot lawn mower is a machine designed to work on lawns that are level and free of uneven surfaces.

Before making a purchase, you should therefore check that your lawn is suitable; if it isn’t, you’ll need to make it so by removing any potholes, steps or uneven patches. A separate point (which we’ll return to later) concerns slopes, as these do not prevent the robot from being used but merely affect the choice of the most suitable model.

 2.1. Lawn size and layout

The first thing to consider is the size of your garden; this is precisely why the recommended area is always specified by the manufacturer as the main selection criterion. There are, in fact, models for all sizes, from small domestic lawns to large sports fields; in this case, the difference between the machines is determined by various features of the robot, such as:

• Battery life;
• Motor type;
• Cutting mechanism;
• Installed software;
• Algorithms used for movement.

It is always advisable to opt for a model with a slightly higher recommended area than the actual surface to be mowed (for example, if the garden is 800 s.q. m², consider a robot recommended for at least 1000 s.q. m or even more), so as not to place excessive strain on the robot and compromise its long-lasting durability; this is all the more important if the area has a particularly complex shape or is full of obstacles

 2.2. Slopes

The second factor to consider is the gradients; not all robot lawn mowers are capable of tackling steep slopes, so if the garden has significant changes in level (up to 45–50%), opt for a robot with 4×4 drive; conversely, if the area is mainly flat, choose a more traditional model with two-wheel drive, which is still capable of handling the small slopes found almost everywhere in lawns.

The very latest models, moreover, can even handle extreme slopes, thanks to the integrated traction provided by four-wheel drive.

3. Robot lawn mower batteries

 3.1. Types of batteries

There are various types of rechargeable battery in use, which obviously make a difference between robot models.

• The oldest and cheapest type is the lead-acid battery, commonly used in cars; it is an older-generation battery and therefore very heavy, prone to memory effect and long charging times, which reduces its capacity over time and requires recharging during periods of inactivity.

• Lithium-ion (Li-ion) batteries, on the other hand, are a new generation; they are currently the best batteries on the market and are now used in all portable devices (smartphones, tablets, laptops, etc.). They offer greater battery life whilst being much lighter; furthermore, they are minimally affected by the memory effect and lose very little charge when idle, charging time is much shorter than with the previous types; however, they still need to be recharged during the robot’s downtime. To overcome this, there is an improved version of these batteries (Li-ion+) that allows them to be charged just once a year without compromising their functionality.
• Finally, there are lithium-polymer (Li-Po) batteries, a different type from the previous ones, which have the advantage of being ‘mouldable’, improving the robot’s shape, assembly and efficiency. They are also safer in the event of damage, as the polymers used are less flammable.

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 3.2. Battery life

When we talk about battery life, we are essentially referring to capacity, and therefore the battery’s power. It goes without saying that more powerful batteries make the robot more efficient and therefore better suited to large gardens; they are also capable of mowing the lawn more quickly.

Linked to the topic of batteries, there is a further distinction that may be of interest when making a purchase, namely whether an automatic or semi-automatic robot lawn mower is better.

• The automatic robot is more practical and convenient as it is fully autonomous. When the battery discharges, it returns to its charging base on its own and is then ready to work again. It is obviously recommended for larger lawns.
• As for a semi-automatic robot, however, if the batteries discharge, it must be manually returned to its charging base. This model has the advantage of being significantly cheaper and may be advisable for gardens with separate areas featuring paved surfaces or paths, which would make installation more complex in the case of fully automatic lawn mowers.

Where should the robot lawn mower’s charging base be placed?
The ideal location for the charging base is on flat ground, with enough free space around it and, if possible, in the shade.

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4. Installation and technical features

By now, we should have a fairly clear idea of the type of robot best suited to our situation; all that remains is to decide which system we want to use and which technologies interest us.

 4.1. Perimeter installation

Most robot lawn mowers operate using a perimeter wire and a docking/charging station, which must be installed along the edges of the garden and around any obstacles such as trees, flower beds, etc…

How do you lay the perimeter wire for the robot lawn mower?
The wire can be laid on the grass and secured with pegs, which are usually supplied.

How deep should the perimeter wire be buried?
The wire should be buried shallowly (to a depth of about 2 cm) using special manual or electric wire-burying tools.

What is the perimeter wire for?
As well as defining the working area and any critical zones, the wire acts as a guide for the robot to return to the charging base when the battery is running low, minimising the need for human intervention.

With this system, the first time the robot lawn mower is started, it will map the perimeter using a GPS system, memorising the working area to make mowing even more efficient. If the robot does not have GPS, however, it will mow the grass randomly within the perimeter of the perimeter wire.

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 4.2. Robots without a perimeter wire

Which robot lawn mowers do not use a perimeter wire??

The alternative is a robot lawn mower that does not use any kind of cable, but which uses sensors to recognise grass-covered areas and any obstacles, thus remaining autonomously on the lawn and eliminating the need for initial installation. Technological advances in the robot lawn mower market in recent years have, in fact, made models without a perimeter wire increasingly functional, thanks to various sensors, cameras or depth sensors that stop the robot in the event of steps or swimming pools, preventing unpleasant accidents and making this category of robot extremely autonomous.

In the case of robot lawn mowers without a perimeter wire, the mowing area must necessarily be demarcated by kerbs, low walls, hedges or paving. This also applies to the most modern robot models, which require a visual boundary to effectively determine where the ground to be mowed ends. What we have just stated remains true even though the most modern models may have a built-in camera or specific anti-collision sensors, which recognise the working area and avoid obstacles in their path.

If the battery runs out, this category of robot can behave in two different ways, depending on the model you have:

1. some will need to be manually returned to the charging base,
2. others, the more modern and technologically advanced ones, will return automatically once the mowing session is finished or in the event of rain. In the latter case, the machines will interrupt the mowing session and resume when possible.

Furthermore, there are types of robots that can be programmed for specific days and times, allowing for autonomous mowing sessions.

4.3 Autonomous robot lawn mowers

Some robot lawn mowers without perimeter wire may also be equipped with GPS sensors which, combined with RTK (Real-Time Kinematic) technology, have made it possible to move away from ‘random bounce’ mowing algorithms, giving rise to the so-called AGS or Active Guidance System.

But what is AGS technology? How does the combination of GPS signals and RTK technology work?

This technology utilises signal triangulation between:

1. satellite,
2. antenna (usually connected to the robot’s base),
3. robot lawn mower,

to precisely determine the robot’s exact position on the ground to be mowed. It is only by knowing its exact location that the robot can understand how and where to cut the grass within the ground, ensuring a precision of approximately 2 cm during mowing.

Thanks to the combination of GPS and RTK sensors, the robot is able to learn and map the layout of the garden and the quality of the signal from the satellites. This mapping, which can also be managed via an app, is continuously updated as the satellites complete their orbits, as the robot requires a good signal between itself and the satellites at all times. In this way, the robot will never lose the signal, avoiding the risk of interruptions whilst mowing the ground. This is why it is important to follow the antenna installation instructions to the letter, positioning it in an elevated spot with no obstacles in the immediate vicinity to block the sky.

These robots are also referred to as autonomous or self-installing, as, following an initial learning phase, the autonomous robot lawn mower will have mapped both your lawn and the sky above it, knowing exactly when and where the satellite signal is strong enough to allow it to mow uninterrupted, whilst also identifying the areas where it still needs to work.

 4.4. Collision sensors

It goes without saying that, in terms of installation, the more complex the perimeter and the more features there are in the garden, the more demanding the initial set-up will be.

To overcome this, the most advanced models, whether they are equipped with a perimeter wire or not (such as the autonomous ones), are fitted with sensors to avoid obstacles. On the one hand, this eliminates the need to install the cable around flowerbeds, trees, bushes, etc., thus combining the efficiency of models with a perimeter wire with the ease of installation of those without. On the other hand, in models without a perimeter wire, this allows any obstacles not included in the original lawn map to be detected and, if necessary, added later after the robot has repeatedly encountered them in the same position.

Furthermore, collision sensors ensure that the robot lawn mower does not collide with people, animals or objects. At the slightest contact, it reverses and changes direction.

4.5. Lawn mapping

• The lawn mapping function ensures that the robot does not mow over sections of the lawn that have already been mowed. The robot lawn mower is therefore able to recognise which parts of the garden have already been mowed and which still need to be mowed. This naturally saves time and makes the job more efficient.

• Even more advanced is the multi-zone lawn mapping function, ideal for green spaces comprising several ‘separate’ areas. In such cases, it will be necessary to programme different settings depending on the specific area of ground to be mowed. It is also possible to link several lawn zones together so that the robot can move autonomously across the ground to be mowed. Please note that mapping can be managed via dedicated apps developed by the manufacturers.
• Once the robot has finished mapping the working area, it will only activate its cutting blades when necessary, i.e. when it finds grass to cut.

• This is also linked to the blade safety lock function: the blades stop if the robot tips over.

5. Mowing

Robot lawn mowers generally have a double or triple blade, depending on the model, power and size of the robot itself.
It is important to note that the robot does not simply cut the grass, but shreds it. Furthermore, it is the user who adjusts the cutting settings, such as the cutting height, according to their needs.

 5.1. Mulching

Essentially, robot lawn mowers are characterised by mulching, using pivoting blades.
What exactly is mulching? We’re talking about a cut of a higher quality than that achieved with standard lawn mower cutting blades.

Where do the grass clippings from the robot lawn mower end up?
The mulching blades allow the grass clippings to be shredded and pulverised, and they are then evenly distributed across the entire mowing area.

These tiny particles of grass will not float on the freshly mowed lawn but will settle directly onto the soil, decomposing very quickly.
They will thus act as fertiliser for the new lawn, transforming into nutrients and water (in fact, grass is composed of over 70% water).

The lawn’s biological cycle is thus complete: what is removed is returned to the lawn itself. Under normal conditions, the aesthetic result after mowing will be comparable to that of a mower with a grass collector, with the advantage that mulching eliminates the need to arrange for grass disposal..

 5.2. Cutting close to the edge

Edge cutting, or side cutting, deserves a special mention. Only a few robot models boast this feature. These models are therefore able to cut the grass as close as possible to the edge of the lawn, minimising the need to use a manual trimmer. With other robot models, the edge remains, and maintaining it is a task that requires more time and effort from the operator.

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6. Smart Features and Safety

• As regards the management and programming of the robot, most robots on the market are equipped with Wi-Fi connectivity. This means that, using dedicated apps developed by the manufacturers themselves, we will be able to set up, programme or even control the robot directly from our smartphone or tablet in an immediate and intuitive manner. This system also allows you to apply software updates periodically, ensuring your robot is always up to date and operating at full capacity.
• For models without remote connectivity, these operations can be carried out easily and clearly via the display and buttons located directly on the robot.
• Some models feature an interface with smart home devices such as Alexa, so we can manage mowing and diagnostics with a simple voice command from inside the house or remotely via a smartphone.
• Until now, it was believed that, for robot lawn mowers, random ‘bouncing’ was the best way to mow a lawn. Today we know this is not the case; the algorithms used in the new models are increasingly efficient because, upon reaching the edge, the robot, rather than turning blindly , calculates the best direction and optimises its route. This means fewer passes are required and therefore less time is needed to complete the mowing, reducing wear and tear on the machine and improving the evenness of the ground.
• The most advanced models may also feature a built-in camera, which helps to further improve the robot’s orientation and obstacle detection. Thanks to this technology, the robot can better interpret its surroundings, moving with greater precision even in complex gardens or those with obstacles to navigate, thereby increasing efficiency and safety whilst working.
• Last but not least is the issue of safety. All robot lawn mowers operate in complete safety as they are equipped with a lift sensor. In the event of excessive slopes, which would expose the blades, the motor’s rotation is immediately stopped, making it safe even in the presence of pets or children.
• Most robot mowers have a rain sensor that sends them back to the base in bad weather, thus preventing them from cutting wet grass.
• Many models come with anti-theft systems such as personal passwords or PINs and audible alarms. In some cases, it is also possible to lock the robot and locate it via GPS in the event of theft.

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6.1 The very latest technologies

What are the latest technologies that are making robot lawn mowers increasingly autonomous and intelligent machines?

• Among the most advanced technologies is virtual mapping, which allows the robot to create a detailed map of the working area. This results in a more orderly, precise and efficient cutting path, with better management of the lawn’s zones and fewer overlaps.
• The most advanced robots also feature LiDAR mapping systems, a technology that uses laser sensors to detect spaces, obstacles and the layout of the working area with great precision. This allows the robot to move with great accuracy even in complex gardens or those with many obstacles to navigate around.
• Some higher-end models incorporate GPS mapping, which is useful for precisely locating the robot within the garden, improving coverage of the working area and, in some cases, managing multiple cutting zones in a more advanced way.
• A further development is radar mapping, used in the most sophisticated models to detect obstacles and movements in the surrounding environment in real time. This is a particularly advanced solution that improves navigation capabilities and makes the work even smoother and safer.

7. How to clean a robot lawn mower?

Unlike traditional lawn mowers, it is not necessary to clean the robot lawn mower after every use.
However, it is advisable to clean the blades and the underside of the housing after a week of continuous use.
In addition to the longer intervals between cleaning, it is worth noting that cleaning a robot lawn mower is much simpler, as it can be easily turned upside down, thanks to its light weight and the absence of liquids inside it.

How to clean a robot lawn mower??
Simply clean the blades by removing grass clippings with a brush or rinse it using a standard garden hose.

It is important to note, however, that this cleaning method can only be used on models where the manufacturer specifies it as a possible cleaning method. In winter, before a long period of inactivity, it is advisable to give the robot a thorough clean.

Given its compact size, it can easily be stored in a closed, weather-protected area, along with its charging station. As for the boundary wire, once buried, it can remain exactly where it is without needing to be removed due to lack of use.

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8. The best brands

There are several leading brands in the robot lawn mower sector, and they all vary in terms of specific features and additional functions.

WHAT IS THE BEST ROBOT LAWN MOWER?

Ambrogio;
Gardena;
Worx;
Yard Force;
Robomow;
Stiga;
Wiper.

9. Frequently asked questions from our customers