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build my own powered / electric wheelchair out of manual wheelchair?

Hello,

Newbie here! I was hoping to convert my manual wheelchair into an electric powered one.. What would be the best way to go about this? Could I just install hub motor on the real wheels? Or would a gear motor be better? I was planning to control it using arduino as I would eventually want to make it gaze-controlled (working on the eye tracking code at the moment..if anyone has any advice for that to that would be great!) It is a really important project following an ALS diagnosis and it would mean everything if I could make this work somehow..I am not based in the EU but have family in the UK who could send me over the parts if they don't deliver. I know it can be cheap to just buy a second hand powered wheelchair but where I am it is not so easy to come across and eventually I would have to adapt it to anyway..I also thought it could be a fun project for me to work on as I was an engineering student. 

Also is arduino the best way to control it, I am using the viola-jones eye tracking algorithm in matlab..


Thanks for any help! Also if you cant help directly even links to pages that can help would be useful :)))



Downunder35m4 months ago

I did some work on and with electric scooters and wheelchairs.
Converting a normal wheelchair into something battery powered needs consideration on several levels.
a) You don't really want to go over the weight limit for frame or wheel mounts.
b) You don't want the batteries to be so heavy that they put too much additional load on the motor to move the thing.

A normal hub motor is usually only running to assist or to run from a starting speed.
The ones that power electric bikes without any pedal assist are usually quite expensive.
Next problem would be that you actually need two as otherwise you always get a drag to side with the powered wheel.
There are options for a click on motor that works through a friction coupling with the rubber on the wheel, like a dynamo in reverse.
Mostly petrol powered though but the same working principle could be applied to your wheelchair.
Of course you would need high pressure in your tires for this to work properly.
Another option could be a chain drive if your wheels are mounted below seat level.
Adding an axle between the wheels would allow to use a sprocket and chain drive to power both wheels.
You would need to allow for a free drive of both sides to use two motors or a clutch/differential between them.

IMHO the best option for most standard wheelchairs would be to extend the axle for the wheels to allow for a sprocket or pulley - chain or belt drive.
Speed control input could be from a salvaged playstation controller.
The analog sticks can be misused to give you directional and speed input from a single stick.
A little arduino with suitable motor drivers for your design is all you need - well plus some coding, time, workshop horrors....
With a setup like this you can go for several motor types to suit your need for max amp usage, rotation speed, torque and size.
Main thing is to have strong starting torque unless you are ok with "push starts".
Although quite demanding on the power side the motors with gearbox from cordless drills are often a good testsubject.
Cheap ones often use a worm drive on the motor side and on this and with some screws you can mount the sprocket or pulley.
The evs are quite high, so you want a small size on the motor, maybe just big enough to be properly fitted.
For the drive side you need to experiment in size to get the desired speed.
Might be enough to get you going and figure things out so you can make a more informed decision on a proper sized motor.
If in doubt 24V scooter motors do a great job here and if you can salvage the controller and drive gear even better.

NadaA2 (author)  Downunder35m4 months ago

Thank you very so much!! Ok so I think I will exit the hub motor out, I have some money I have saved to use towards the project but I dont want to spent it all on two hub motors :) I think an axle may be the way to go.. do you have an example of this being done in practice sorry I dont know what is meant by using the controller of the playstation to control can I not do this through the arduino or do I need both? Also how long do you think this kind of project can take, there is already limited use in one of the hands and not sure how rapidly will progress to other hand...the reason I want to understand the controller better is so I can figure how to interface with the eye tracking because the standard joytick controller will probably not be of use within the next year unfortunate

iceng NadaA23 months ago

Still unsure after all the good ideas and excellent advice.

Have you not looked at the Related column ===========>>>>>>

rickharris4 months ago

https://www.google.co.uk/search?q=powered+wheelcha...

many designs here, Always start design by looking at what commercial projects have done.

Most powered wheel chairs have small wheels, most manual wheel chair have big wheels.

Most powered wheel chairs use differential steering through 2 motors one on each main wheel.

These motors are geared usually with a worm drive to give a relatively high torque, low speed output and they are driven by 1 or 2 Sealed Lead acid batteries so 12 or 24 volts.

It will prove expensive and as part of your research I would look at the local cost of buying one ready made.

Parts are available and often used to build electric cars/Karts.

Good luck.