As often happens while engaged in a mundane task, my mind wandered while I was mowing my small suburban plot of green this weekend. “Why, in 2017, am I still mowing the lawn?” In a lot of ways we’re living in the future — we walk around with fantastically powerful computers in our pockets, some of us have semi-autonomous cars, and almost anything can be purchased at the touch of a finger and delivered the next day or sooner. We even have robots that can vacuum the floor, so why not a robot lawnmower?
It turns out we do have robotic lawnmowers, but unfortunately, they kind of suck:
Bearing in mind that the video was produced by Husqvarna, it should come as no surprise that their entry in the robotic Lawn Care Leduc field was the top performer, and that other variables that would likely have challenged all the mowers equally, like tall, wet grass, were not tested at all. What I saw in the video was a bunch of mowers that all suffer from a couple of basic problems that answer my question of why we don’t see robotic lawn mowers in every suburban yard.
You might think my main beef is the universal need for wires to define borders for the robots. It would be nice to see a fully autonomous robot that could locate the flower beds just using GPS and image analysis, but wire boundaries seems like a reasonable means to the precision needed to keep the bots contained. Wire boundaries are akin to “invisible fencing” for dogs, and the one-time cost of installing the wire would be amortized over years of having a robot handle one of my weekly chores. That’s a different article — [Will Sweatman] already did a great job covering automonous robot location tracking tech.
The real problem I see is a lack of power. Each of these robots is powered by batteries and they seem terribly underpowered both in terms of drive train and cutting. The lack of power is most evident in the inability of most of the tested units to deal with hills, but some were not even especially good at cutting grass. A lot of the cutting ability seems to have to do with the compromises made in the blades’ design — there are no massive steel blades on these bots. The most successful are essentially whirling razor blades that won’t survive a real-world yard where rocks, tennis balls, fallen tree branches, and pine cones the size of a chihuahua are common obstacles.
There’s a reason your average walk-behind lawn mower uses a fire-breathing internal combustion engine: nothing beats it for concentrated, portable power. The blade spinning beneath the deck of the mower has an incredible amount of energy behind it, enough to cut the grass, mulch it into tiny bits or blow it into a bag, and still have enough left over to move the machine around so you don’t have to. As noisy and environmentally unfriendly as it may be, the internal combustion engine is king of the greens, and even though battery and motor technology has come a long way, it’s hard to see that they’ll be able to match a gas engine’s power to weight ratio anytime soon.