Suggestion: Mid-Drive Powered Wheels, Six Total

This is a message from the Local Motors Projects website from @SpeKterDesn (Gavin):

Fun piece of work Andy!

As a person about a pinch away from needing a motorised bottom half at times can I make one suggestion even just for a fun chair in the office?
I didnt see it written anywhere above and you may have considered it but not wrote it down yet, but in terms of footprint (and helps put it on any chair), mobility (fun) and turning circle (important in offices) have you considered moving the driving wheels to the middle of the sides of your platform and having balancing castors front and rear so you end up with 6 points of contact with the ground as well, you can even add suspension for uneven floors and surfaces.
Just a small suggestion on the drivetrain that I think may make all the difference to the implementation of your product. I hope its feedback well received and like I said you may have had that trick up your sleeve already just hadn't seen it mentioned before.   ;)



Hey Gavin, thanks!

Yes, that particular idea was an early one. There is a prototype platform of that idea in the garage. It was only a little bit more rectangular than square, as in it had a short wheelbase. I didn't ever get around to adding suspension beyond quick-fix foam rubber layers between the platform and the casters. It was a bit bouncy and not nearly as stable as what I have at the moment, but again, it was a rush job.

When I get new video up of this current revision, you'll be able to see that this can turn in a perfect circle in-place. It's about 30" stem to stern and is exactly as wide as that silly Ikea Poang chair. Aside from a smaller-than-average closet door, it fits most doorways, especially those in offices.

I figured that design might be a plausible option later when I can actually weld a proper and more robust chassis from metal parts, not plywood and 2x4s. ;) I also think that it would stabilize with some sort of small shock absorption system, like the rear frame shocks from mountain bikes. It needed play for getting over bumps but also needed occasional stiffness.

The other drawback to increasing feet-on-the-ground, as it were, is the added complexity: More parts. One goal I had in mind for the serious side of this thing (there are equal parts comedy in this chair, of course) was to make it as inexpensive as possible by creating a BOM from off-the-shelf hardware and parts and to keep that BOM as short as possible.

The fix for clearing more rugged doorway thresholds, curbs and poorly maintained parking lots is the greater ground clearance and the pneumatic scooter tires. This thing navigates over the worst of doorway transitions and nasty sidewalks quite well and even at higher speeds (not smart, necessarily, but great for your daily adrenaline fix).

Either way, though, thank you so much for contributing ideas! The chassis will be the first thing to get love at LM Labs, methinks. Input from people like you will help immensely!


Andy Frey

My name is Andy and I am a maker. Enough about me. How are you? What did you have for lunch yesterday? Have you made anything cool lately? OK, back to me: I like to make things, with or without purpose. Clocks, shelves, machines that turn themselves off, homemade circuit boards, IKEA chairs with motors, etc. I love to learn how to manufacture stuff myself. I also love to take things apart to see how real-world products are engineered.