RC Lawn Mower Complete

[Peter]

Pretty happy with this project. I got the most of the parts from SDR (including motors, wheels and hubs). It isn’t the upfitter kit they sell, but is based on its design. I wanted to fabricate my own frame and and this is the final result. Also added Arduino boards for failsafes and blade shutdown if it encounters an obstacle (bendable pressure strip).

I made the front casters detachable on welded struts so I could replace them if the caster size didn’t work out, and in case I wanted to modify these in the future. I also switched to Grade 8 all thread for caster stems as Grade 5 bends too easily if you hit something.

Only thing I would do differently is rethink the front wheels. You don’t realize this until build is complete but swivel casters on bumpy hills (if you need to mow sideways) are difficult to steer. All in all it was a fun winter project and I have learned to drive it well enough now to do the whole yard. The original intent was for it to do around tree bases with overhanging branches just to save my back. Once I learned how to modify the expo curve on the transmitter, I became a better driver and now do the entire yard this way.

The RC stuff (Spektrum DX6) was the hardest part as I had a big learning curve on this. Originally I had a linear actuator that adjusted deck height for the grass length; however, the geometry of it just didn’t work. It made the wheel base so long that cutting around tree bases (my real objective) was impractical. So I ditched that mod.

I left the mag brakes functional on the motors and added a couple of relays to control them from the transmitter. They don’t draw that much power and the mower battery runs out long before the drive wheel batteries anyways. Future mods will be a solar panel on the roof of the garage I made for it to charge the drive batteries.

This was a perfect mix of metalworking and electronics for me, and tons of fun. Thanks to SDR for making the PDF plans of the pre-built mower they used to sell available online. It wasn’t exactly what I wanted, but gave me a starting point and confidence to proceed. I’m in Canada and they were easy to deal with for shipping of the heavy motors, etc.

One last note—I used 16 gauge steel to make the electronics box as it was going at the front of the mower and I knew it would take a few hits. Considering my initial driving mishaps, this was a great decision.

Video of it operating is here: https://youtu.be/ijYupzHGIqY

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