DIY Autonomous Mower In The Wild

Mowing the lawn is one of those repetitive tasks most of us really wish we had a robot for. [Kenny Trussell] mowing needs are a bit more strenuous than most backyards, so he hacked a ride-on mower to handle multi-acre fields all on it’s own.

The mower started out life as a standard zero turn ride on lawn mower. It’s brains consist of a PixHawk board running Ardurover, an Ardupilot derivative for ground vehicles. Navigation is provided by a RTK GPS module that gets error corrections from a fixed base station via an Adafruit LoRa feather board, to achieve centimetre level accuracy. To control the mower, [Kenny] replaced the pneumatic shocks that centred the control levers with linear actuators.

So far [Kenny] has been using the mower to cut large 5-18 acre fields, which would be a very time-consuming job for a human operator. A relay was added to the existing safety circuit that only allows the mower to function when there is weight on the seat. This relay is wired directly to the RC receiver and is controlled from the hand-held RC transmitter. It will also stop the mower if it loses signal to the transmitter. To set up mowing missions, [Kenny] uses the Ardupilot Mission Planner for which he wrote a custom command line utility to create a concentric route for the mower to follow to completely cover a defined area. He has made a whole series of videos on the process, which is very handy for anyone wanting to do the same. We’re looking forward to a new video with all the latest updates.

This mower has been going strong for two years, but in terms of hours logged it’s got nothing on this veteran robotic mower that’s been at it for more than two decades and still runs off an Intel 386 processor.

Where Are The Autonomous Lawnmowers?

It’s impossible to know when society began to manicure its front lawns. Truth be told — cutting the grass was, and still is a necessity. But keeping the weeds at bay, trimming, edging and so forth is not. Having a nice lawn has become a status symbol of modern suburbia all across the globe. When the aliens arrive, one of the first things they will surely notice is how nice our front lawns are. This feature of our civilization could have only been made possible with the advent of specialized grass-cutting machines.

reel mower
Reel Mower [Public Domain]
It could be argued that the very first lawnmowers were live stock. The problem was they were quite high maintenance devices and tended to provide a very uneven cut, which did not bode well for families striving for the nicest front lawn on the dirt road. Coupled with the foul odor of their byproducts, the animals became quite unpopular and were gradually moved out of site into the back yards. Other solutions were sought to maintain the prestigious front yard.

The first mechanical lawnmower was invented in 1830 by a man named Edwin Budding, no doubt in an effort to one-up his neighbor, who still employed a Scythe. Budding’s mower looked much like today’s classic reel mowers, where a rotating cylinder houses the blades and rotates as the mower is pushed forward. Budding was granted a patent for his device by England, much to the dismay of his fellow neighbors — most of whom were forced to buy Budding’s mower due to the fact that everyone else in the neighborhood bought one, even though they weren’t actually needed.

By the early 1930’s, the cold war started by Budding and his neighbor had spread to almost every front yard on earth, with no end in sight. Fast forward to the modern era and the lawn and garden market did 10 billion in sales in 2014 alone. Technological advances have given rise to highly advanced grass-munching machines. For smaller yards, most use push mowers powered by a single cylinder IC engine. Many come with cloth bags to collect the clippings, even though everyone secretly hates using them because they gradually fill and make the mower heavier and therefore more difficult to push. But our neighbors use them, so we have to too.  Larger yards require expensive riding mowers, many of which boast hydrostatic transmissions, which owners eagerly brag about at neighborhood get-togethers, even though they haven’t the slightest clue of what it actually is.

Us hackers are no different. We have front lawns just like everyone else. But unlike everyone else (including our neighbors) we have soldering irons. And we know how to use them. I propose we take a shot-across-the-bow and disrupt the neighborhood lawn war the same way Budding did 85 years ago. So break out your favorite microcontroller and let’s get to work!

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Castrol Virtual Drift: Hacking Code At 80MPH With A Driver In A VR Helmet

Driving a brand new 670 horsepower Roucsh stage 3 Mustang while wearing virtual reality goggles. Sounds nuts right? That’s exactly what Castrol Oil’s advertising agency came up with though. They didn’t want to just make a commercial though – they wanted to do the real thing. Enter [Adam and Glenn], the engineers who were tasked with getting data from the car into a high end gaming PC. The computer was running a custom simulation under the Unreal Engine. El Toro field provided a vast expanse of empty tarmac to drive the car without worry of hitting any real world obstacles.

The Oculus Rift was never designed to be operated inside a moving vehicle, so it presented a unique challenge for [Adam and Glenn]. Every time the car turned or spun, the Oculus’ on-board Inertial Measurement Unit (IMU) would think driver [Matt Powers] was turning his head. At one point [Matt] was trying to drive while the game engine had him sitting in the passenger seat turned sideways. The solution was to install a 9 degree of freedom IMU in the car, then subtract the movements of that IMU from the one in the Rift.

GPS data came from a Real Time Kinematic (RTK) GPS unit. Unfortunately, the GPS had a 5Hz update rate – not nearly fast enough for a car moving close to 100 MPH. The GPS was relegated to aligning the virtual and real worlds at the start of the simulation. The rest of the data came from the IMUs and the car’s own CAN bus. [Adam and Glenn] used an Arduino with a Microchip mcp2515 can bus interface  to read values such as steering angle, throttle position, brake pressure, and wheel spin. The data was then passed on to the Unreal engine. The Arduino code is up on Github, though the team had to sanitize some of Ford’s proprietary CAN message data to avoid a lawsuit. It’s worth noting that [Adam and Glenn] didn’t have any support from Ford on this, they just sniffed the CAN network to determine each message ID.

The final video has the Hollywood treatment. “In game” footage has been replaced with pre-rendered sequences, which look so good we’d think the whole thing was fake, that is if we didn’t know better.

Click past the break for the final commercial and some behind the scenes footage.

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