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Lawnmowers, the new generation of robots

The fully automated garden machine is not only able to cover the required perimeter by itself, but also to connect with advanced digital systems that optimise its work. Choosing a robot means opting for a lower impact on the soil, but also on the environment in terms of emissions and noise

by Pietro Piccarolo
March - April 2023 | Back

At the European level, the use of electric motors in the lawnmower fleet for grass cutting has now become almost equal to that of mowers with endothermic engines. Within electrified machines (cordless and battery-powered), robot mowers account for about 20% and make up more than 50% of battery-powered machines. By 2030, it is expected that electrically powered mowers will be twice as numerous as those with endothermic engines (which will decrease significantly) and that robots will make up about 30% of electrically powered mowers.

The strong market growth of robots is linked to: the fact that they are silent machines (60-70 dB), non-polluting and completely autonomous; the diversification of the offerings to meet the different dimensional and orographic types of turfgrass; their continuous technological evolution. These are all elements that have attracted the interest not only of hobbyists and individual garden owners who feel freed from burdensome and repetitive work, but also of green area maintenance professionals.

The commitment of the manufacturers has been growing and this has led to a very wide market offering, with variously evolved models suitable for cutting areas between 400 and 30,000 square metres. For the different models, the investment required is different, ranging from 400-600 euro to 5,000-7,000 euro, but they can also exceed 10,000 euro.

Some common features include mulch cutting and being powered by lithium-ion batteries. The autonomy of the robot with one battery is around 60-90 minutes and can reach 4 hours with 3 batteries. The cutting apparatus can be a star-shaped with four points or a disc with protruding blades placed on the circumference of the disc itself. The blade speed is around 3,000 rpm and reverse rotation is also possible. Cutting widths range from 20 to 30 cm with a single blade, up to 120 cm with several blades placed on pivoting blade arms to better follow the contours of the ground. The cutting height is adjustable between 20 and 60 mm, but can also reach 80-100 mm in the larger models. There are normally two machine drive wheels, but there are models with four drive wheels and also tracked robots. The slopes within which they can operate are 30° to 35°. In models with wide, high traction wheels and tracked models, slopes of up to 50° can be achieved.

Since 1995, the year in which the first robot lawnmowers began to be introduced onto the market, there has been a strong technological evolution, so we speak of successive generations. The evolution has concerned both aesthetics, with bodies made of different materials and even carbon, to make them lighter and more resistant, and lithium-ion batteries, which are increasingly high-performance and with shorter recharging times, as well as innovations in operation. There is an increasing use of sensors. These range from the use of ultrasonic sensors to avoid obstacles, be they flowerbeds, trees or shrubs, to sensors that detect rain and make the robot return to its base, and those that, by detecting the height of the grass, control the variation of blade speed. Programming the machine's work in terms of cutting height, working time, etc., can be done directly on the robot's digital screen and also from smartphones and tablets. Voice recognition is also provided. GPS-assisted navigation with satellite technology allows centimetre-level accuracy. Some models, thanks to cloud computing, implement the work cycle according to grass growth. It is possible not only to remotely programme the robot's activity, but also to remotely know the working parameters, such as working time, distance travelled, power consumption and other parameters. Connection is possible not only with the owner but also with the dealer in order to guarantee continuous remote assistance.

The most common solution involves defining the cutting areas with a perimeter wire that is secured to the ground with staples, or buried, and then connected to the robot's loading station. This must be placed near a socket, on a flat surface and with a surrounding area free of obstacles. It has to be said that installation is an operation that requires some effort and should be done by a professional. It is normally preceded by an analysis of the site to define the layout, obstacles, socket points, etc.

Through specific Apps it is also possible, again using satellite technology, to define the virtual perimeter of the cutting areas without resorting to physical delimitation with the material laying of the perimeter wire. The App makes it possible to virtually define different areas of the lawn and set customised cutting programmes for each individual area.

In essence, the latest generation of lawnmowing ro­bots have become increa­singly smart machi­nes, than­ks to Internet of Things (IoT) sensors and algorithms based on Artificial Intelligence (AI).

There are several strengths to be taken into account when purchasing a robot lawnmower, and they are not just about freeing the operator from noisy, strenuous and repetitive work. The robot is a machine that is not only silent but generally lighter than conventional lawn mowers and this leads to a reduction in soil compaction, especially in conditions of high soil moisture. Cutting the grass regularly improves lawn quality and limits evapotranspiration by reducing the need for irrigation.

The tiny strands of grass that are deposited with each mowing quickly mineralise, bringing nutrients to the turf. The vibrations transmitted to the soil remove the risk of mole settlement. This is offset by the higher investment in the purchase of the robot (including the perimeter wire) compared to a conventional lawnmower, which, however, is offset by lower maintenance and operating costs as well as low CO2 emissions. It has been estimated that to perform 150 cuts per year on a football pitch, the CO2 emissions amount to approximately 145 kg/year, which is 10 times less than that of a ride-on mower.

The choice in purchasing a lawn mower should therefore be made with a great deal of knowledge, considering not only price but also running costs, performance, quality of work, environmental impact also in terms of noise pollution, and the service provided by the dealer.


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