Guidance on Meauring Hand Reaction Force Project Using Arduino Uno

Any help is welcome, thanks.

I have no idea what you mean by "hand reaction force". Have you measured it so someone can suggest a way to automate the measurements?

Paul

Interesting; do you plan on using some device BETWEEN the wheel and hand?
Or load sensors on the axle?
Can you provide a sketch - and links to the examples you have cited?

Hi,
I think the OP wants to measure the arm force required by the wheelchair operator to push a wheelchair wheel.

This could prove difficult because as the hand rotates around the section of arc although the force will be at a tangent to the wheel, the arm will not be at a tangent.
If you watch some of the wheelchair sportsmen and women, they get a rolling action to smoothly transmit force to the wheel.

If you knew the mass of the chair and occupant, you could measure the acceleration of the chair and directly calculate the force at the circumference of the wheel, this however would not include the extra effort to overcome friction.

Tom... :slight_smile:

yes but ..
to measure it directly you need a force - ometer between wheel and hand, as the tyre is not "readily" adaptable to those measurements.

If you knew the mass of the chair and occupant, you could measure the acceleration of the chair and directly calculate the force at the circumference of the wheel, this however would not include the extra effort to overcome friction.

or rolling resistance of the wheel, or gravity. Or changing direction.

The only way I can see is to measure the forces on the wheel axle (which is constrained in degrees of freedom) and measure the CHANGE when the hand force is applied.

Paul_KD7HB:
I have no idea what you mean by "hand reaction force". Have you measured it so someone can suggest a way to automate the measurements?

Paul

Sorry, I was not clear. By hand reaction force this the reaction force between the hand and the wheel during proulsion.

johnerrington:
Interesting; do you plan on using some device BETWEEN the wheel and hand?
Or load sensors on the axle?
Can you provide a sketch - and links to the examples you have cited?

Yes both is viable ideas I have thought about. The problem is what eaxct load cells/force tranducers that can integrate with an arduino uno and the designing a model for them in or besde the wheel is a real struggle.

Example studies and experiments:
https://www.tandfonline.com/doi/full/10.1080/15438620903120637?needAccess=true

https://www.ati-ia.com/Library/documents/OptiPush_Biofeedback_System_Flyer.pdf
Validation of a Biofeedback System for Wheelchair Propulsion Training

TomGeorge:
Hi,
I think the OP wants to measure the arm force required by the wheelchair operator to push a wheelchair wheel.

This could prove difficult because as the hand rotates around the section of arc although the force will be at a tangent to the wheel, the arm will not be at a tangent.
If you watch some of the wheelchair sportsmen and women, they get a rolling action to smoothly transmit force to the wheel.

If you knew the mass of the chair and occupant, you could measure the acceleration of the chair and directly calculate the force at the circumference of the wheel, this however would not include the extra effort to overcome friction.

Tom... :slight_smile:

Yes this is exactly what i'm investigating. Yes this is the problem i've faced, the free body diagram's shoing forces at play are very complex. The wheelchair propulsion mechanism's in itself are very complex too. Finding a way to simplify this to calcuate a slightly accurate reaction force is the problem.
Unfortunately , I do not have a budget large enough to afford a whole chair so I am using a wheel on its won. The wheel of choice is a mag type wheel (the wheel includes a rubber wheel and pushrim).

johnerrington:
yes but ..
to measure it directly you need a force - ometer between wheel and hand, as the tyre is not "readily" adaptable to those measurements.

or rolling resistance of the wheel, or gravity. Or changing direction.

The only way I can see is to measure the forces on the wheel axle (which is constrained in degrees of freedom) and measure the CHANGE when the hand force is applied.

Thanks , this sounds like a very viable method. Do you have any idea of what components could be used to meaure the CHANGE in reaction force when applied.

attached is an example FBD

fbd.JPG

fbd.JPG

You would need to mount load cells around the wheel bearing.
They would need to be able to take the weight of chair and occupant at rest plus a margin for driving force.

johnerrington:
You would need to mount load cells around the wheel bearing.
They would need to be able to take the weight of chair and occupant at rest plus a margin for driving force.

I do not have a budget to afford a whole wheelchair , so I am required to just use a wheel. Can this still work with just the wheel if so how many load cells is needed.

adam272000:
I do not have a budget to afford a whole wheelchair , so I am required to just use a wheel. Can this still work with just the wheel if so how many load cells is needed.

Not very likely as you need the whole weight of the chair plus the occupant in order to measure the force needed to move the whole chair.
Of course, you will need to measure both wheel forces in case the occupant cannot exert the same force on each wheel.

Where have you tried to find wheel chairs? Telephone some of the nursing homes in your area and see what they do with their old chairs or ask who repairs their chairs and contact them for a test unit. likely no cost at all!

Paul

If you know how hard the push feels, fix a heavy weight to the axle-mounted wheel so the weight is at the bottom. Push the wheel by hand harder and harder to raise the weight until you push max hard. Knowing mass, radius and angle, push can be known.

GoForSmoke:
If you know how hard the push feels, fix a heavy weight to the axle-mounted wheel so the weight is at the bottom. Push the wheel by hand harder and harder to raise the weight until you push max hard. Knowing mass, radius and angle, push can be known.

Now thats lateral thinking, Edward de Bono would be proud.

Paul_KD7HB:
Not very likely as you need the whole weight of the chair plus the occupant in order to measure the force needed to move the whole chair.
Of course, you will need to measure both wheel forces in case the occupant cannot exert the same force on each wheel.

Where have you tried to find wheel chairs? Telephone some of the nursing homes in your area and see what they do with their old chairs or ask who repairs their chairs and contact them for a test unit. likely no cost at all!

Paul

Thannks, unfortunately it has to bought from an approved supplier so picking up a free one form a nursing home is not possible. I have chosen a mag type wheel, lastly, are you suggesting there is no way to mesure the reaction force with just propelling one fixed wheel?

GoForSmoke:
If you know how hard the push feels, fix a heavy weight to the axle-mounted wheel so the weight is at the bottom. Push the wheel by hand harder and harder to raise the weight until you push max hard. Knowing mass, radius and angle, push can be known.

This sounds like a great idea thanks! But it has to involve a mechancial and electronic components hence why chocie arduino uno, the trouble is my force sensing element and how it can intergrate with an uno.

So this is a commercial development?
Yes, I am suggesting that. And it will vary by whomever is setting in the chair and doing the attempt to move the wheel.

Paul

No. becasue the forces acting an the wheel are balanced by both wheel bearings, you would need to have quite a latge part of the wheelchair.

The only remaining avenue I can think of would be to sense pressure changes in the tyre but that would be very one-dimansional.

Paul_KD7HB:
So this is a commercial development?
Yes, I am suggesting that. And it will vary by whomever is setting in the chair and doing the attempt to move the wheel.

Paul

No, it is just an assigned project. It's seeming impossible with the options available to me. thanks !

johnerrington:
No. becasue the forces acting an the wheel are balanced by both wheel bearings, you would need to have quite a latge part of the wheelchair.

The only remaining avenue I can think of would be to sense pressure changes in the tyre but that would be very one-dimansional.

Yes, wow thats agreat idea of measuring pressure changes in the tyre. Could you possible explain this more, possibly what compnents it would involve and would it require a calculation to calcuate to respective forces from the presure changes?