How to choose a robotic lawnmower
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What is a robotic lawnmower?
Robotic lawnmowers are gardening equipment that automatically cuts grass. In terms of their “behavior,” they are similar to robotic vacuum cleaners, which you are probably already familiar with. At a certain time (according to a schedule or on command), the robot leaves its charging station and starts mowing the lawn, and when the energy in the battery is exhausted, it returns to the base to recharge. A typical robot is a compact, battery-powered device with a wheeled chassis and a rotary cutting system “hidden” under the body.
Robots don't work very fast. As a rule, they move at a speed of about 1.5 km/h and process about 30 – 50 m² per hour. That is, in terms of performance they cannot compare with conventional lawn mowers. But the robots act independently and work completely autonomously, without requiring unnecessary attention. However, tech who are used to being in control can optionally control the operation of the equipment, program and customize its behavior (via the control panel or remotely) to achieve the perfect lawn with minimal effort.
Advantages and disadvantages of robotic lawn mowers
Robots have a number of advantages over conventional lawn mowers.
- High quality lawn. The robot is ideal for tech who like short-cut lawns with a grass height of 20 – 50 mm. Unlike a regular lawn mower, which is used once or twice a week, a robot mower works every day or every other day. Therefore, the vegetation is mowed a little at a time and is less injured. The cut ends of the plants are so small that they do not need to be collected. Plant residues fall to the ground and serve as organic fertilizer, which benefits the lawn.
- Quiet operation. The noise volume from a modern robotic lawn mower usually does not exceed 60 - 65 dB. This is approximately equal to the noise level from the outdoor unit of the air conditioner and quieter than the volume of voices of people having a normal conversation. That is, the robot detects its presence only by the quiet hum of electric motors and the cutting system. Thus, the equipment during operation will not interfere with your rest or cause displeasure to your neighbors.
- Saving time and effort. The robot eliminates the need to spend a couple of hours on the weekend “walking” around the property with a lawn mower. It works while you rest. Caring for equipment comes down to cleaning it only (from time to time, but preferably at least once a week) and replacing knives (approximately every 4 to 6 weeks).
Robot care procedure using the Stiga lawn mower as an example:
However, this type of gardening equipment also has certain disadvantages that may put off some potential users.
- High price. Even the most budget-friendly lawn-mowing robots start at $400, which is quite a lot compared to regular lawn mowers, not to mention trimmers. Although they are quickly becoming cheaper and more popular, not everyone can yet afford to buy a robotic lawn mower.
- Installation required. Unlike a regular mower, which you can simply bring onto your lawn, there is usually some work that needs to be done before you use the robot for the first time (this is discussed in detail below). The installation process is not particularly complicated or time-consuming, but it may discourage tech who prefer simple and quick solutions.
- Not for every lawn. Robots run great on flat areas with well-groomed lawns. But not every one of them is able to cope with caring for a personal plot with neglected vegetation or uneven terrain. It happens that a robotic mower can get stuck in a tree trunk, skid on a slope, or fall with its wheel into a wormhole.
How does a robotic lawnmower navigate in space?
Manufacturers of gardening equipment have come up with several technologies that allow robots to navigate the site and understand where they are and where to go.
- Boundary wire. The perimeter of the lawn is outlined using a special cable, which is connected to the docking station and is under low (absolutely safe) voltage. The robot, encountering a cable, “feels” electromagnetic radiation using a special sensor and understands that it should turn around and go in a different direction. If the lawn is divided into several separate zones, then using the same wire, the robotic lawn mower is shown the route from one area to another. In order for equipment to avoid obstacles within the perimeter outlined by the cable, robots are equipped with shock sensors (almost always) and obstacles(sometimes).
- Satellite navigation. For orientation in space, GPS sensors are used, as well as 4G and Wi-Fi modules. The robot remembers the satellite passage schedule and the signal strength from each of them in order to create an optimal work schedule. Since “communication” with satellites can be interfered with by tree branches and building walls, sometimes it is necessary to install a repeater or signal amplifier on the roof of a house - this technology achieves the highest accuracy in calculating the robot’s position (± 2 cm).
- Machine vision. The robot is equipped with a high-resolution camera and a processor for processing the resulting image. The image from the camera is analyzed by a neural network or artificial intelligence, previously trained to detect the presence of obstacles in the path of the lawn mower and distinguish grass from other surfaces. As of 2024, such robots have not yet become particularly widespread (primarily due to the high price), but they are the future.
Installing the boundary wire for the robotic lawnmower
Almost half of the operating instructions for the robotic lawnmower are devoted to how to properly prepare the area and lay the boundary cable. Recommendations from different manufacturers may differ slightly, but in general the installation procedure will be something like this:
- The area should be thoroughly cleared of foreign objects, such as rocks or fallen branches, and the lawn mowed short using a regular lawn mower.
- You need to find a good location for the charging station. The base is installed on a flat and level area not far from an outlet, preferably in the shade (so that the robot does not overheat during charging and resting).
- The wire is laid along the perimeter of the lawn and around areas where the lawn mower should not go (swimming pool, flower bed, tree trunk, etc.). The cable must not cross itself. It is necessary to use templates provided by the manufacturer of garden equipment to accurately maintain the distance between the wire and objects at the edges of the lawn (paths, borders, fences and building walls), turning radii, width of “corridors”, etc. Otherwise, the robot will cling to its side over obstacles or leaving thin strips of grass unmown.
- The boundary wire must be pulled tight and pressed to the ground with pegs - special fasteners that are usually included in the kit. The cable can be laid directly on the surface (over time it will be hidden by grass) or buried 2 - 3 cm underground. Underground installation is more labor-intensive, but it protects the wire from accidental damage.
- The power cable and both ends of the boundary wire are connected to the charging station. The order of further actions depends on the model of lawn mower, since robots from different manufacturers study their area differently during the first start.
The process of installing the docking station and boundary wire in preparation for the first use of the Bosch Indego robotic lawnmower:
Trajectory of robotic lawn mowers
Depending on how “smart” the robot is and what sensors it is equipped with, the lawn mower’s trajectory can be random, ordered, or carefully thought out.
The simplest and cheapest robotic lawn mowers have an arbitrary trajectory. When the robot hits a boundary wire or encounters any obstacle, it backs up slightly, turns left or right at a randomly selected angle, and then continues moving straight. Having reached the perimeter of the lawn or hitting an object, it again backs away, turns around, etc. This process is repeated until it is time to return to the docking station to recharge. Despite some randomness, this method of choosing a trajectory ensures that the robot will sooner or later cover almost every square centimeter of the lawn.
Some robotic lawn mowers have “advanced” logic. They try to “push off” from the boundary wire or obstacles at certain angles, moving in more or less orderly zigzags. By choosing more “thoughtful” trajectories, such robots get through bottlenecks better, work a little faster and waste less energy because they don’t make unnecessary movements. “Advanced” logic also includes the ability to mow grass, moving in a spiral from the edge of the plot to its center.
Some modern robots have a mapping system. When first launched, they remember the size and configuration of the site, as well as all objects on the territory. Before leaving the charging station, the robot “in its mind” builds the optimal route in such a way as to complete the maximum amount of work in the shortest time with minimal energy consumption and not miss a single piece of the lawn. To do this, a robotic lawn mower requires good electronic “brains”, so this technology is more expensive than simpler models.
Setting up and programming a robotic lawnmower
Modern lawn mowing robots are easy to set up and program. Therefore, even tech who are not familiar with technology can easily master the principles of control.
Almost every robotic lawn mower can run on a schedule. The user has the opportunity to set a mowing schedule for different zones, adjust the frequency of mowing the lawn (for example, daily or every other day) and the duration of the “work shift” of the equipment. Some of the most “advanced” robots have certain knowledge of agronomy and can themselves create an optimal work schedule, taking into account the area of the lawn, the composition of the soil on the site, the type of grass, the type of fertilizer applied, the intensity of watering the lawn and the climatic characteristics of the region (all of this information is entered into the program by the user ). Many models have Wi-Fi modules that allow you to control the lawn mower and program its behavior using a smartphone or tablet with a special application installed.
Robot lawn mower and rain
All good robotic lawn mowers have a water resistance rating of at least IPX3 (protected against raindrops up to 60° from the vertical) or IPX4 (protected against water splashes from any direction). This means that the electronics and battery, “hidden” under the body of the device, will not fail even during heavy rain. The most modern robots usually belong to classes IPX5 (protection from water jets from any direction) or IPX6 (protection from strong water jets from any direction). Such models can even be washed using a garden hose or a mini washer with low operating pressure.
However, many robots have rain sensors. When a sensor detects the presence of precipitation is triggered, the robotic lawn mower “reels in” and returns to the docking station. The meaning of this behavior is to avoid cutting wet grass, which is not useful for the lawn itself (heavy wet blades of grass are not cut with a knife, but are torn) and harmful to the robot (the load on all components and mechanisms of the device increases).
Brief conclusions
Summarizing the above, we come to the conclusion that robots can be a useful aid for tech who want to keep their lawn in perfect condition with minimal effort. The robotic mowers presented in our catalog are excellent for maintaining small to medium-sized lawns (from 100 m² to 1000 m², and sometimes larger). Unfortunately, robots are not yet able to clean up neglected areas overgrown with weeds, bushes and tall vegetation. But they cope no worse than humans with maintaining order and painstakingly cutting the grass on the lawn every day.
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