off Road Wheelchair

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off Road Wheelchair

Postby Jeffa » December 8th, 2013, 5:56 pm

I am a quadriplegic an I have no use of my arms or legs. I operate an electric wheelchair with sip and puff control. I need help figuring out how I can control up to 6 separate Heavy duty 4-pole dc motors with a sip and puff input control devices. (Or electric golf cart motors)

I would like the vehicle to operate much like the one in the attached video.
[YouTube]http://www.youtube.com/watch?v=6ECyxPJeGII[/YouTube]

Please, any help and direction would be greatly appreciated.

Thank you
Jeffa
 
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Re: off Road Wheelchair

Postby Mjolinor » December 9th, 2013, 3:22 am

Interesting problem which probably needs much input and discussion so I'll start it off and maybe other people can expand or suggest other possible solutions.

As you only have 2 inputs then the only other inputs you can get are time and pressure/vacuum (volume and direction) . For safety reasons you need to have a "stop all" input that is quick.

After a quick google it seems that these SNP devices generally only offer 4 inputs from soft or hard / suck or blow. I can't see any reason why it should be limited like that and measurement of quantity of air (or speed) could be quite accurately measured giving a reasonable facsimile of analogue control.

When you sip and puff do you actually pass air through or is it a sealed vessel that you have in the receiver, ie. pressure/vacuum operated? If you actually pass air through then do you suck from the lungs or the mouth?


With modern motor control electronics individual motor control can be done automatically so there is no reason to have more than direction and speed.

So one way would be to have "sip" rotate the needle on a clock (speed of rotation controlled by amount you suck) such that 12 was all forward, 9 was spin left, 6 was all backwards and 3 was spin right with all positions between dictating % of left and right motors, once set then "puff" could control speed of execution in that direction.

Quick "puff" (or sip) to stop and for smooth travel you would want execution of the direction input to not take place until the long "puff" after setting.

First stab at a method, it needs refining and the problems sorting out, I have to admit to having never considered this sort of thing in my life, head in the sand syndrome.
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Re: off Road Wheelchair

Postby k-ww » December 9th, 2013, 6:21 am

I have read of a wheelchair controller that is based on sensing the position of a small magnet on the tounge, being sensed by electronics outsid the mouth, giving in effect, a 3 dimensional joystick.

Also, the off road wheel chair seems to have only 2 motors, each coupled to 3 wheels on each side, which would make control a lot easier.

The 3 coupled wheels on each side should work better than 3 independant motor because if one slips, the other 2 wheels keep that one from spinning uselessly.
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Re: off Road Wheelchair

Postby Mjolinor » December 9th, 2013, 8:28 am

k-ww wrote:I have read of a wheelchair controller that is based on sensing the position of a small magnet on the tounge, being sensed by electronics outsid the mouth, giving in effect, a 3 dimensional joystick.

Also, the off road wheel chair seems to have only 2 motors, each coupled to 3 wheels on each side, which would make control a lot easier.

The 3 coupled wheels on each side should work better than 3 independant motor because if one slips, the other 2 wheels keep that one from spinning uselessly.


A real use for tongue studs!!! :eek:

I just watched it again and you are right, it does not have 6 separate motors, it is the same control as any tracked vehicle. Not very efficient really, independent control would be much better and can easily be all automatic.
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Re: off Road Wheelchair

Postby Jeffa » December 9th, 2013, 10:09 am

"When you sip and puff do you actually pass air through or is it a sealed vessel that you have in the receiver, ie. pressure/vacuum operated? If you actually pass air through then do you suck from the lungs or the mouth?"

The way my wheelchair works is as follows:
a hard puff latches both drive motors in first gear,If I want to increase the speed again I puff hard again into the straw and it latches into second gear. (5 gears total) I do not have to continually blow to keep the chair moving forward while it is in gear. If I give a light continious sip the Chair turns to the left and if I give it a light continious puff the chair turns to the right. If I do not give a command within 6 seconds it automatically stops. I also have a head switch which I use as a break. This switch stops the chair immediately and it also helps me toggle through different functions on my chair when it is stationary.

I am about to get another wheelchair because mine is 10 years old. I was wondering if I could use the same sip and puff control from my wheelchair and incorporat in the build of the off-road chair.
I am not looking for speed. 6 miles an hour would be fine, which is about what my wheelchair does now.
I need to do some homework on the exact motor I should use that is a good match for the wheel diameter and overall system weight. I know there are a lot of components and aspects to this build that need to be addressed. I am just trying to find a starting point and take it one step at a time.

Instead of having to transfer to this off-road chair. I want to use it as a transport for my personal wheelchair. I want to Make it large enough to strap my wheelchair onto so I do not have to be confined to it when I get to my destination.

Thank you guys for showing interest in this project. I am not just dreaming of this to happening I am going to make it happen. It is so frustrating for me not to be able to travel a trail or explore the woods because of one single obstical that is only 2 inches high which prevents me from doing the things I love.
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Re: off Road Wheelchair

Postby TravisCucore » December 9th, 2013, 8:12 pm

I read this recently and it seems to fit the bill

http://www.medicalnewstoday.com/articles/269526.php

Or maybe not. Just something to consider
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Re: off Road Wheelchair

Postby Mjolinor » December 10th, 2013, 4:34 am

As you want to keep your existing control system and the vehicle you point to has only two motors there is really nothing to be done other than some specific interface electronics that will directly connect each of your existing signals to the tractor's existing signals.

This is probably very trivial but does need someone on the ground to look at both systems.

That type of vehicle is not going to be cheap whether you make it yourself, buy it or have it made.

If I were spending that much money then I think effort spent putting rails and automatically retracting ramps up the tractor for the wheelchair and locks and connections to fix the wheelchair in place and make the transfer of control automatic operated with the SNP mechanism would be my first priority so that there is no need to swap seats when changing vehicles.
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Re: off Road Wheelchair

Postby Jeffa » December 10th, 2013, 2:58 pm

I have an EZ Lock system that I can mount to the floor of the transport. Then all I have to do is back up the front ramp with my chair and lock in.

I found this sire today and I am trying to educate myself in this area so I can ask the rite questions.
http://www.mpoweruk.com/motorcontrols.htm

I also found this site. I am going to pick their brain to see what kind of motors/controler they think will fit my build.
http://www.ddmotorsystems.com/

In the youtube video attached. Is this electric torque converter, or just another motor?
http://www.youtube.com/watch?v=PhbjDULRdu8

Attached is some rough design work on the proposed off road wheelchair transport vehicle.
WT TRANSPORT VEHICLE front. jpg.jpg

WT TRANSPORT VEHICLE iso back shot. jpeg.jpg

WT TRANSPORT VEHICLE side view.jpg
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Re: off Road Wheelchair

Postby k-ww » December 10th, 2013, 4:48 pm

That's just an electric motor, look close underneath it, and you can see the driveshaft between wheels turning.

If you are building something from scratch, put the platform for the wheelchair on a pivot, with a half gear setup [half circle] driven by a motor and wormgear [the wormgear setup will keep it from moving/tilting when the motor is not powered] , with a sensor, to automaticly keep the platform upright as you go up/downhill.
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