Date:2 August 2013
One suburban homeowner’s quest to automate his lawn into submission. By Glenn Derene
For some people, moving the lawn is a meditative experience – a chance to tune out while getting a little exercise walking behind the lawnmower, inhaling the scent of freshly cut grass. It’s good old-fashioned domestic man’s work, like your father did before you, his father before him, and so on. Well, not me. I hate mowing the lawn. It’s a numbingly repetitive, sweaty, noisy waste of time. My father hated it too. And I’m pretty sure his dad
Tell you what I do like, though: robots – love ’em! In fact, I would gleefully surrender every thankless bit of home landscaping to an automaton. So I decided to see if I could piece together a system wherein my lawn essentially would take care of itself. Yes, I could have hired a landscaping crew, but to me that was a dodge. I didn’t want to pass off my dirty work to someone else. That’s the beauty of robots – one day they may take over the world, but for now, they get the grunt work.
And, it’s worth mentioning, I wanted a beautiful lawn – green, lush, carpetlike – something my family and I could really roll around on during a midsummer day. I just didn’t want to sweat for it. The good news is that, for mowing, there’s already a robot solution – a couple of them, in fact. Honda sells the Miimo; a company called LawnBott offers a variety of, well, lawn bots; and Friendly Robotics has a bunch of really friendly looking mowing robots. All of these systems seem pretty similar and promise essentially the same thing: to tame your turf with a minimum
I called up Husqvarna, a company with a long history in the grass-cutting biz. Husqvarna also has deep experience with robotic lawnmowers; it introduced the first consumer model in 1995. Now it sells two: the Automower 230 ACX and the Automower 265 ACX. A few weeks after my call, I got a big box with a 265 ACX and an appointment with company representatives Quinn Derby and Gent Simmons. They arrived a few days later, surveyed my postage-stamp-size lawn, looked at the box from their company, and concluded that the 265 was complete overkill. But the machine was there, so they decided to install it anyway.
Now, two animal analogies are useful for understanding the operation of the Automower. First, the machine works like a sheep, roaming about your lawn at random, nibbling away at the blades of grass in small increments. Second, the Automower is prevented from leaving your lawn in much the same way that a dog can be contained within an electric fence. That’s what Derby and Simmons installed on my lawn – a fence for the robot. They laid down a low-voltage wire that creates a mild electromagnetic field so the robot can sense when it has reached the prescribed boundary, then reverse, turn randomly, and proceed off in another direction.
Derby informed me that my lawn was an unusual one for the Automower. That’s because I really have two lawns: a small one in the front of the house, and a larger one in the back, separated by a fence and a patio. I could tell that Derby is by nature a problem solver, as he described several ways he could attempt to string the wire to allow the robot to travel from my back lawn to the front lawn. But I imagined the poor, confused machine attempting to nudge aside patio furniture along the way, and I told Derby to fence them off separately – occasionally I’d just pick the thing up and move it to the front lawn myself.
The two men installed the perimeter wire and base station and then gave me some brief advice on programming the mower – an hour, for four days a week, would keep the back lawn neat and tidy; 1 ½ hours once a week would handle the front.
It was bliss. Every Monday, Tuesday, Wednesday, and Saturday at 1 o’clock, the mower would back out of its charging dock and quietly go about its business until 2 o’clock, when it would find its way back. The mower is so quiet that I considered rescheduling it for the middle of the night. My 4-yearold son, Owen, protested. Watching the mower cruise across the lawn had become one of his favourite activities. On Sundays, after setting it on the front lawn, I would uncap a beer and hand Owen a juice box, and we would sit in the rocking chairs on our porch and watch the Automower go – ironically, paying more attention than ever to our lawn.
It was easy to anthropomorphise the thing. We found ourselves talking to it (“You missed a spot!” “Look out for that tree!”), dogs barked at it, and the sidewalk passersby found it fascinating.
“It’s so cute!” said the woman from two houses down. “It’s like a Roomba for your lawn.”
Then there were those who found it ominous: “Aren’t you afraid it’s going to cut your toes off?” said one kid who nearly fell off his bike when he first saw it. The answer was no. The Automower is loaded with sensors designed to prevent injuries. In addition to collision detection that makes it back off the instant it touches anything, it has a lift sensor that stops and retracts the recessed blades if you try to pick it up. According to Derby, the biggest problem Husqvarna has seen with the Automower is kids trying to ride on top of it. It’s enough of an issue that the mower now ships with a sticker warning against it.
Robotic mowers are a rarity in most areas. However, they are popular in Europe, where landscaping services are particularly expensive. But automated seed and fertiliser spreaders don’t exist anywhere. I know, because I checked. So I decided to create such a machine myself.
Well, not entirely by myself. I called up Randy Sarafan, technology editor at Instructables and an occasional PM collaborator. He had previously roboticised an RC monster truck, which I figured would make a good platform for a spreader. I thought we could mount a handheld spreader to the top of Sarafan’s robot truck, then connect a belt drive from the axle of the truck to the crank of the spreader. Every time the truck moved, it would spread the good gospel of grass. I bought an RC truck to test it out. The truck struggled to move itself through thick grass, so there was no way it was going to power a spreader as well. Sarafan suggested starting from scratch with an Arduino-controlled, dual-motor, tracked platform with an independent third motor driving the spreader. He could pull that off easily, he said.
Guidance would be the tough part. At first I figured the little spreader could use the same guide wires as the Automower, but a quick talk with PM senior home editor Roy Berendsohn exposed that as a bad idea. It’s okay for a mower to move randomly within a defined space, he explained – you can’t overmow a lawn as long as the blades aren’t set too low – but letting a seed-and-fertiliser spreader loose like that would be a waste. Sarafan designed the robot with a sonar proximity detector and a clever set of instructions. My main patch of lawn is rectangular and bordered on two sides by a fence, so the robot would start at one edge and count the number of revolutions of its wheels until it sensed the fence in front of it. Then it would turn around and progress back the same number of wheel revolutions until it reached the other side of the lawn, and repeat. He tested the thing at the Instructables headquarters in San Francisco, then shipped it to me on the East Coast.
It was quite a ceremony at the Derene house when I first brought out the seed bot. My wife and Owen and his baby brother, Elliot, all came out to see its maiden voyage. I had high hopes for the little machine – the only one of its kind on Earth. I filled the hopper and flipped the robot on, and off it went, rumbling slowly on its treads with a spray of seeds shooting out in front of it. But our excitement was short-lived. The little bot made it halfway to the fence, stopped, turned, and progressed back at a cockeyed angle, lumbering diagonally across the lawn towards my wife’s Volkswagen in the driveway. “Daddy, stop it!” cried Owen. “It’s going to hit mommy’s car!” I ran after the wayward bot, which was still flinging grass seeds all over the place, picked it up, and turned it off. In its undisciplined way, it had spread seed on about onequarter of my lawn. Not a complete failure, but not quite a success, either. Sarafan and I would have to make some code corrections and maybe adjustments to the sonar. But that would come later. Right then, I did what any good husband, father and homeowner would do. I got out my old conventional seed spreader and finished the job myself. Total robot lawn domination would have to wait.
PM editor Glenn Derene with his son Owen and their lawnmowing robot.