Instructables

Step 2: Parts

Picture of Parts
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Parts Needed:
  • Chair - Any type will do. Something comfortable that you can lay back into.
  • Arduino UNO - Check your local suppliers or eBay.
  • Sabertooth 2x52 Motor Controller- www.dimensionengineering.com or a local supplier.
  • 5 DOF accelometer www.ebay.com/itm/181004141876?sPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
  • 2 scooter motors - I would recommend 200w and up. www.oatleyelectronics.com or eBay. Have a look around your area.
  • Batteries - SLA batteries are good and cheap, Power drills can be quite inexpensive too.
  • Wheels - Larger wheels are better for bumps. Get one with the same sprocket chain type as the motors if possible.
  • We got our wheels from www.oatleyelectronics.com
  • Shielded multi-core cable for the accelerometer and heavy power cable for the motors
  • Deadman switch
  • Toggle switch for turning. A joystick is good for this.
  • Toggle switch for adjusting balance position.
  • DC connector for Arduino.
  • DIL pins to suit Arduino
  • Double sides tape
  • Screws etc 
  • Metal tubing for the frame

 







 
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Hi ScitechWA,
Well my boys and I are embarking on a build based on your SciChair...we have purchased all the items including the 5 DOF accelometer (linked to in the parts list) and can't seem to work out how to wire this in to the circuit based on the different board layout. Can you provide some guidance on this...

We live in Adelaide and hope to have our self-balancing "cockpit" up and running in a few months...we would also love to send some photos and perhaps video when we finally get things sorted.

Thank you for all the info in your instructable, it seems pretty straight forward and gave us the confidence to embark on our journey :)
wootin243 years ago
Hi, i was wondering about the motors used in this project. do i have to use geared motors or can i just use a 300 watt scooter motor to drive it. thanks
Awsome 'ible i've been looking at XenonJohns builds for a while and have been considering making a skateboard but this may have to come first, I was wondering what kind of speed or power you can get out of it, like does it have the power to go up inclines and maintain a safe speed on declines? Also I have looked at the arduino code before and is there a speed limiting parameter or is it just zero to full power with the 255 setting? Thanks for the great 'ible.
kelseymh3 years ago
A technical comment. This is an awesome chair. If a real wheelchair user wanted to use it, they would have to have some way to support their legs. You might think about how you could add a lightweight frame (some bent tubing and footpads) while still maintaining the balance and stability, for version 2.
Wragie kelseymh3 years ago
Having been stuck in a damn wheel chair off and on while this would be a hell of a lot of fun it really isn't suitable as one. It simply too low for a handicapped person. Standing I'm just over 6 foot. In a chair you come up to peoples bellys so about 4 ft. And even that is too low to reach for things set for normal access. Trust me if you ever want to get your eyes opened on what a pain it is, borrow one for the day and strap yourself down (so you can't cheat) and try it around the house and if you are brave the super market.
kelseymh Wragie3 years ago
I am pretty confident that these folks did not design something for a wheelchair user -- rather, they designed a chair with wheels. I do suspect that if they replaced the small tires with proper high-strength wheels (say, from a Quickie sports chair), it might be an interesting option.

Having said that, though, I tend to be extremely conservative. I hate the Segway model of trusting your safety to a dynamically compensating computer, rather than to a passively stable equilibrium.
Wragie kelseymh3 years ago
I actually just had responded to the one comment on using it for a "wheel chair" by a poster. To me it sounded like he did want to try it as a mobility, that was the way I read his post. As I said as a fun thing it would be a blast to zip around in. Not everyone you see in a chair is 70 years or older some of us are in our 40's and still dumb enough to want to play with these other things, Me I still want to build a unicycle, the big wheel one. If you borrow the levelling /balancing it might even be ridden able by mere mortals. ;-]

Personally I do keep an eye out on these projects for idea that would make mobility type chairs better. I had to use one just enough to know what a total pain they are. One instructable that still stands out to me and the guy really truly deserves some kudos is a fellow in Morocco who was scrounging the junks yards for scrap steel, batteries, and old office chairs to make them. He was building these for next to nothing. Even replicating his build with everything off the shelf was under $500 here. That impressed me enough I spent 6 months trying to talk the so called charity/service organizations into looking into it. Seems they would rather spend $2K on a standard chair instead of spending the same on something that would actually make a difference to someone.
kelseymh Wragie3 years ago
I'm pretty sure you were responding to my own post, and correctly :-) I had commented that the pictures didn't include any kind of foot/leg support, which would be needed by a real chair user.

"Not everyone you see in a chair is 70 years or older" -- Um, not at all. The guys who play murderball can't be over thirty, or I think they'd all be dead :-)

Your comment about local (U.S.) organizations preferring to pay for a commercial chair than to build their own has a lot to do with (a) the medical/insurance model, and (b) liability. If you build a chair from scratch, and give/sell it to someone else, then you are liable if it fails, or worse, if it fails in such a way as to cause injury. Consequently, you are much better off buying a commercial device, for which the manufacturer has assumed that liability.
ScitechWA (author)  kelseymh3 years ago
Thanks for the replies guys but I think we are getting off topic here!
I don't want to get into the politics of medical insurance!

I hope you understand.
I promise not to rant on about insurance or insurance sales droids without mentioning the use of chainsaws, axes or a industrial wood chippers. ;-]

Seriously you guys have something here that is just so damn close to being a real godsend to some people. You do need to realize that and keep it in mind.

Cheers
Wragie kelseymh3 years ago
The shame about it is very innovative things like this will never make the leap from toy to tool as a result. I had meant to say to the guy(s) who wrote this I hope they keep it in mind there is a huge market for assist devices and there is money to be made and people that can be helped at the same time. And I did get off track by not saying that. Initially ;-] Actually thinking about it you could add a safety wheel fore and aft and it would work for some people. If it had the range (without having to stop off at the construction site along the way ;-]) It would make for a very fun run around.
firepup1043 years ago
I was wondering sience im not going to make it ballance im just going to put a third wheel on the back Whould i not need arduino or anything else.
You wouldn't need the self-balancing code, but you would still need a way to switch power to and from the motors. If you want nice controllability, that means a way to either vary the current to the motors or vary their power using PWM.

If I were to make a three-wheel version of this (and with the cool self-balancing code already done, why not just do it that way?), I would still use an Arduino or PIC to control the motors (via a series of FETs or something, since an Arduino or PIC could barely handle switching 400mW by itself (you'd have to use a large PIC and switch several pins together), let alone 400W.

Besides, if you built it with a third wheel but stuck as closely to the original design as possible, you might be able to swap XenonJohn's balancing code in and take off the third wheel at some point...
kelseymh3 years ago
This is so close to being a Featured I'ble!

You need to add pictures to the three steps which don't have them. Please, please, add a set of photos of the components to Step 2 (your own photos for the big stuff, steal some obvious clip art for the little things (resistors, tape, blah blah blah) and of the tools you used to Step 3. On the final step, you could add a picture of the chair in action.