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.

39 thoughts on “Lawn Dog Faithfully Cuts the Grass

      1. Autonomy. He’s hacked two products to make an electric self-propelled lawnmower. It would be neat to see if he could use a Roomba to take care of the autonomy part (and not have to control it by RC). I don’t have one, so I don’t know if that’s feasible, but it would be cute.

  1. “As a kid, [Josh] always dreamed of building robots to do his boring, dangerous chores like mowing and weed-eating the lawn.”

    And the kids grow up and have kids. Guess what their first jobs are?

    1. we used to have a ride on mower- when taught to drive it at age 7 i thought i was the king of the snapper, which admittedly was a bit dangerous (dry grass piled up around the engine and the deck was a bit rotten)

  2. Gas and electric, meh. Most mowers make as much pollution doing a lawn as driving a ‘clean’ car about 170 miles according to the EPA. I would go with tracks if wheels fail. I have a hill that only tank tracks could mow. I have heard of robot mowers that get stuck in a hole and just spin away forever. Good for mowing a flat golf course sans gophers, only 9 or 18 holes to deal with…

  3. Move the wheels of the mower to the edge so they stick out beyond the nose and it’ll do the bottom of hills better.

    Looks like I need to publish my hack of the Jazzy Joystick protocol so the only hacking on the Jazzy would be to add an ESP8266 or Arduino with wireless or maybe rPi.

        1. upvote. I need this too. I have my chair broken down ready to make into a modular multi-purpose chore bot but wanted to forego the removal of the electric braking(not sure if that’s the term) that comes with the motors and using a sabertooth.

          1. I’ll dig up the project and put up a quick page on gottahackit.com with a reference to the Sketch on github. It was built as a proof of concept and I’ve since disassembled the prototype( a hacked Gravis JStick from the 90s ) but maybe we can get the Nunchuck version working. I’d coded that into the Sketch but never got to testing it.

            I’ll have it up online this weekend.

  4. Is it me, or does neither the article or the project page mention how the Brain of this monster Works? The Sabertooth either takes RC PWM or serial but it is not connected in the Picture of the innards? Is the order board a WiFi or celluar modem or a Pi with something in top?

    1. He mentions on his page that it’s controlled in RC mode. I expect he used a standard RC receiver and used RC mode on the Sabertooth. I used the Sabertooth 2×25 and RC receiver on my RC mower. The big downside is that Sabertooth reset’s it’s center position while it’s being used. So after I’m done mowing, the mower will wander because the Sabertooth has changed the center and it’s no longer in the dead spot between forward/reverse or left/right. Sabertooth wouldn’t work with me on this problem…

      1. I’ve used the 2×25 Sabertooth with the small encoder board they Also Sell. IT keeps the wheels in sync so IT drives straight and the curves are perfect archs.

        1. About centrering RC pots, use a digital transmitter. IT filters the potentiometer so Center position dedband is digitalt synthesized to the excact same value each time. So No creep.

      2. I use the regular micro-controller version of the Sabertooth, It has more features like auto calibration on power up and centers every time there is no input. Pretty cool. I do intend on adding a kangaroo for feedback when it goes full autonomous.

    2. Ardupilot works for RC cars… would be a useful upgrade if he can do some gps beacon shenanigans to improve the location accuracy. Then mowing the lawn would be as simple as loading/drawing a waypoint plot on a map.

      1. Yep, the biggest limitation is the super accurate positioning. There are some DIY differential GPS type solutions but they are still pretty expensive and complicated.

  5. Not enough details. I really want to see the code for the AI that’s running this robot. Gluing a lawnmower to an electric wheelchair is a hack, but a minor one compared to the feat of software engineering required to turn that lump of motors and batteries into a functioning robot. That’s the real interest here.

    1. Ignoring that commenters above + the page linked point out that this is RC driven, it should be painfully obvious from the way the mower is moving that this is RC driven. “The real interest here” is not here. Personally I wouldn’t want an autonomous lawn mower anyway, it’s just like autonomous package delivery. Way to easily stolen, way to easily broken, way to much liability.

      1. Yes, the comments say that it is RC driven. The article does not say it, it speaks of a “robot” which in my understanding clearly works autonomous, at least after the first teach-in or programming.
        I am not sure, if I would prefer a remote controlled lawn mower against direct control.
        Although for sure it is nice, not to smell the stinky engine exhaust. But using 1-1,4l of gasoline for one time of mowing, this needs quite an expensive battery, I estimate 2-3kWh.

  6. “Prime the carburetor and pull that cord there to see Lawn Dog’s mowing and ditch handling skills.”
    Pretty sure you just have to hold down the lever on an electric mower. Or are there electric mowers that emulate a gas mower?

  7. I didn’t watch the video first, and hearing it’s weak audio was still not aware of it’s all electric operation. The first robot mower was back in 1965 the Mobot, it used the “invisible dog fence tech” for boundary. Perhaps 4 wheel drive if not more would help with holes. What works on Mars should work here too. BLDC motors on each wheel? Optical course recognition (like a mouse) to drive in line.

  8. Hello all, yes it is a robot, it has a micro controller, however it cannot run autonomous until I have a border fence of some kind. GPS simply is not accurate enough. I am considering a RF boundary in ground system. As of right now I drive it in a remote control fashion. It is great though! I even mow neighbors from my house at times if they need it. The batteries for the jazzy will last 2 or 3 mows , but the electric mower batteries need to be changed 3-4 times as I only have the small 40 v batteries and not the big 5 ah guy. The code / navigation portions are handled by ez-robot and this is an on going project I only started a few months ago and went dormant since we have had 3-4 months of below freezing weather.

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