E-bike gurus please step in, building a wheelchairiot thing
 

OK, school me boys:)
I want to use two hub motors to power a conveyance that I can roll my in-laws chair into. I have plenty of creative juices going, but no experience with hub motors.
1) I don't want high speeds.
2) Do want high torque to get it started in soft stuff.
3) plan on controlling with differential steering, but may augment it with some sort of front steering.
What say you?

I recently saw a free power scooter on Craigslist. Would something like that work, or provide guts that would work?

I'm thinking regular steering would be smooth and positive control vs diff steering and casters.

http://www.1800wheelchair.com/media/...ca2e52fe3f.jpg

I need to use big wheels to keep it from getting stuck. If I could figure that out it could work.

Differential steering might help in tight corners, like those skidsteer tractors, but I still believe you'd be better off retaining conventional steering too.

Consider direct drive motors rather than geared, because when throttled-off the direct drive will acf as a brake, which is good for a wheel chair. Geared moted will clutch out when you throttle-off, and then you coast. For a wheelchair the free automatic braking seems safer. I liked my experience with ebikes.ca... here is their motors page: Motors - Ebike Parts - Shop

Good for research for you mostly... their smallest wheel is probably the 16" one.

To control speed and torque the motor controller is your key. Also go for a 36v or 24v system... lower speeds...

What kind of range does it need to have?

10 miles? I think he'd like to go down the beach with his grandkids.
I want to put as fat a tire on there as I can for flotation, and probably go with 4 wheels for stability.
The design in mind is a pair of channels that he rolls his conventional chair up onto, that then lift up for ground clearance. Transfers are the enemy.
Now I transfer him into a 4wd rig and then back into his chair and each time we risk an injury that might lay him up for months. Like 6 months.
This only happens once a year or so, but he lives out in farm country and he'd use it quite often if I made it.
I would prefer only differential steering but that is all on the controller we can cobble up, and how to calibrate it for fine control. An e-bike typically has so much speed to it that the controller is not good for the fine stuff. An electric wheelchair controller is, but at high speed it might get dicey :)

I would think you'd want more than 10 ahr in the battery, minimum. More if you can get it. But the system you want to build is kinda alien to me. I have only built this one ebike that I ride. I like Frank's idea of getting some of the guts out of one of those little elderly person scooters. Or maybe check specs and hardware for a few electric wheel chairs. I would think you could learn a lot by studying websites like this: Electric Wheelchair SuperStore - Power Wheelchairs, Pride, Jazzy, Golden

Batec Mobility - Add-on handbikes for wheelchair: manual and power handbikes easy to attach to the wheelchair. Revolutionary anchoring system - Batec Mobility - Handbikes acoplables para silla de ruedas: acoples para silla de ruedas, propulsores para
For once a year this would be overkill, but my buddy has one of these.... actually thats him on the lake pulling his kids. He uses a studded tire in the winter. May help with the creative juices!

sand is the hard part.

I was also thinking of a K.I.S.S. system, depending on how much traction is needed and if the steering effort vs upper body strength of the operator are compatible:

http://i146.photobucket.com/albums/r...pszqnonc58.jpg

Put ATV tires on it and voila! I mean, not that mower but a cart with fwd and 360 deg steering. Your controller could be a contactor switch.

P.S. As you can see the steering on this rig is geared down for low effort. Plus the lack of caster and the fact it's the drive wheel should make it low effort as well.

the once a year is the beach, he would use it now and then all summer if it worked.