Lawn Dog Faithfully Cuts the Grass

As a kid, [Josh] always dreamed of building robots to do his boring, dangerous chores like mowing and weed-eating the lawn. Now that he’s built Lawn Dog, an all-terrain robotic lawn mower, he can kick back and mentally high-five his younger self.

Lawn Dog is the result of hitching the business end of a Jazzy electric mobility chair to a Ryobi lawn mower with a custom flexible bracket, and then tweaking it to handle the worst that [Josh]’s lawn has to offer. It’s powered by two 24 V lawn and garden batteries and driven with a Sabertooth 2X12 motor controller. After a slippery maiden voyage, Lawn Dog now masters rough and green with aplomb thanks to doubled-up omniwheels on the Ryobi and very special tires on the Jazzy.

[Josh] wants nothing to do with weed-eating and mowing the ditch, so it’s important that the Lawn Dog is up to the job. He put some solid rubber tires on the Jazzy and then drove 50 screws into each one to add serious traction. Prime the carburetor and pull that cord there to see Lawn Dog’s mowing and ditch handling skills.

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How to Stop Grandma’s Wheelchair If She Goes Out of RC Range

Okay, so he doesn’t have Grandma riding in it that we know of, but [zim] recently decided to turn a Jazzy mobility chair into “a radio-controlled platform for mischief”. RC offers more range than wifi or bluetooth, and he was able to find a reasonably priced secondhand radio on Craigslist. However, he found out that in the event of signal loss, the receiver keeps sending the last commands to the speed controller. [zim] didn’t want his 150 lb (68kg) mischief platform getting loose, so he devised a fail-safe that cuts power to the motor when the signal is lost.

[zim] discovered that the receiver returns channel 3 (the throttle) to a preset condition whenever the signal is lost. He used a 24V HVAC relay controlled by an Arduino Nano to sample the PW on channel 3 and shut it off when either the throttle or the signal are cut.

If Grandma is feisty, you could build this caged-in version with a shopping cart.

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