Design Engineering

Stihl unveils autonomous lawnmower, uses lawn clippings as natural fertilizer

Devin Jones   

Automation General Quality

The iMow comes in two sizes, depending on the acreage of grass needed to be cut and features a variety of safety sensors.


Power equipment manufacturer Stihl recently unveiled its latest product to the North American market: an autonomous robotic lawn mower of that comes in two different sizes.

Think of a roomba for cutting grass, the iMow—which currently comes in two sizes correlate to the acreage of lawn—is an environmentally friendly mulching mower that uses lawn clippings as an inherent type of fertilizer.

“The main principle of the machine is that because it cuts such a small amount off the top of the lawn, it allows the plant to absorb nutrients in ways a traditionally lawner more wouldn’t,” said Sales Manager Hugh Munn. “With a traditional machine, we often cut off such a large part of the plant, that when it clumps up the lawn is never able to absorb any of it back into the soil, which can cause problems in the long-term.”

According to Munn, the iMow only cuts off the top two millimeters of the designated area, allowing the plant to absorb nitrogen from the clippings back into the lawn. When clippings decompose, they release their nutrients back to the lawn. They contain nitrogen, potassium and phosphorus, as well as smaller amounts of other essential plant nutrients.


Created and tested in Europe by Stihl subsidiary VIKING, the iMow comes in a smaller model (the RMI 422P) that can cut up to a quarter acre at a time and a larger model—the RMI 632P—which can cut up to a full acre on one charge. The device acts like similar robots of it’s kind, with the user setting a parameter around the space they’d like to cut, an invisible fence of sorts, with the iMOW cutting within its designated areas.

Due to an embedded controller (that’s removable on the larger model) users can set the iMow on a schedule, cutting once twice or three times a day if needed. This type of “set it and forget it” model coupled with a low noise emission, gives you the option of mowing the lawn at midnight if you so choose. The smaller model comes with an average mowing time of an hour before it needs to be recharged, but the device saves enough energy to find its way back to the docking station to plug itself in. Another example is if it’s raining For example, the rain sensor tells iMow not to mow and to catch up on the lost mowing time later in the week.

The device comes equipped with a variety of safety sensors, ones you would expect: if the robot were to tip over for example a sensor cuts the power and no further torque is generated from the blades as they come to a stop. What’s more interesting though, are things like the top weight sensor which—with young kids in mind—cuts power to the machine If someone steps on, or sits atop the mower. The device also comes equipped with an anti-theft sensor, setting off an alarm if the device is lifted off the ground and not set back down within a customizable time frame.

“One of the features our customers love is that, with the bigger model using the detachable remote, you can drive the iMow remotely,” said Product Specialist Josee Levesque “You’re cutting your lawn, but it almost feels like you’re playing a video game at the same time.”

According to Munn, Stihl plans on selling 350,000 units within europe by the end of 2018. 


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