Dear Dr. Hassanain,

I hope that my post finds you well, also do you remember me? I am you colleague at Nahrain University, Dept. of mechanical engineering, 2008.

Anyway, please try to clarify your fully valued question. I do not understand what do you want to measure and how?

Regards

Emad

Dear Dr. Lafta Mossa,

I did research on wheelchair propulsion in past, but this is not my research area anymore.

Without any instrument, you would have to use a biomechanical model.

If you are open to using some basic equipment, you may measure acceleration with a smartphone and detecting the touch events with a simple touch switch applied to the handrim.

Kind regards,

Angelo

Hi Dr Emad,

Apologies for my delayed reply. Hopefully everything is going well with you. I just want to evaluate the performance efficiency of manual wheelchair users through calculating the effective component of the propulsive force applied by the hand on the pushrim. Most recent studies are using the Smart wheel device that will measure the three components of the force and moment at the point of force application, so that will facilitate calculating the effective (tangential) force, as well as the efficiency.

Best Regards,

Hass.

Hi Angelo,

Thanks for your answer. I'm currently using the 3D motion analysis technique to evaluate the kinematics of the upper body, so I already measured the joint angles and linear velocity and acceleration at each placed marker on the upper body bony landmarks, but still couldn't find a simplified method to calculate the effective propulsive force from such parameters? Also, I'm really interested in the smartphone idea; do you have more information about it?

Best Regards,

Hass.

Good morning Hass,

thank you!

We had proposed two kinematic indicators of push efficacy that you should be able to calculate already from your data. Ideally, what you would be missing is that circuit we used to identify the touch, which is a really simple touch switch - http://www.electroschematics.com/5996/touch-switch-circuits/

Basically, the indicators are defined as the fraction of push duration during which there is an increase of speed of the wheelchair and as the net relative gain in speed. Figure 3 may help you to understand more of this.

https://www.researchgate.net/publication/228606213_Definition_of_a_protocol_for_geometric_and_kinematic_measurements_to_assess_wheelchair_propulsion

The project may have gone a little bit over and Dr. Carmelo Lentino at Santa Corona Hospital (Italy) may be able to provide you a further update. 

About the smartphone, it was just an idea: using accelerometers for measuring the acceleration of the wheelchair.

Ideally you may want to have one on the person arm(s) and one on the wheelchair, and the "conversion" of acceleration (-> forces) of the arm to acceleration of the speed may be a way of estimating the effectiveness of the push?

You could also consider the momentum, and measuring the speed of the wheelchair may be a way of estimating the work produced by the user!

Kind regards,

Angelo

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