Undergrad Force to stop a person on a treadmill

[canucks]

Here is the link to data..Stopping distance for both 3 KM/h & 6 Km/h
https://www.dropbox.com/s/tstbfod8y...ky's conflicted copy 2015-01-12) (1).xls?dl=0

 

[sophiecentaur]

Here is the link to data..Stopping distance for both 3 KM/h & 6 Km/h
https://www.dropbox.com/s/tstbfod8y0b5zj7/Data Analysis List Old BWSD (Bonita Sawatzky's conflicted copy 2015-01-12) (1).xls?dl=0

You certainly have some measurements there! Can you describe the setup and what was actually measured, particularly with regard to the treadmill?

 

[canucks]

The participants were randomized to begin the study either with or without the 106 drive attached to the wheelchair operating in the indoor mode. Stopping distance data were 107 collected at two different speeds (3.5 km/hour or 2.2 mph and 6.0 km/h or 3.7 mph) with two 108 trials at each speed using a wheelchair treadmill (MaxMobility) at 0.5 degree incline to 109 standardize velocities. Participants were instructed to propel on the treadmill until each speed 110 was reached and maintained for a minimum of three seconds. The researcher then asked the 111 participant to stop the wheelchair while simultaneously turning off the treadmill. In a separate 112 test, tTo measure starting peak total forces and peak speed, participants were asked to propel the 113 chair with “one light push, in order to get the wheelchair going” from stationary on a level tile 114 floor with and without the drive. Participants were asked to repeat the light push task until they 115 were able to accelerate the chair to engage the drive

Here is a picture of smart drive: http://www.max-mobility.com/smartdrive/#mx2pluspushtracker
Weight of participant between : 60-80 kg
weight wheelchair + smart drive : 23.1 Kg

 

[sophiecentaur]

The researcher then asked the 111 participant to stop the wheelchair while simultaneously turning off the treadmill.

I am concerned about this statement because the user has zero velocity relative to the ground. If the treadmill and the chair are turned off simultaneously then there would be no acceleration and no force and the chair would still have zero velocity relative to the ground. The only forces that would occur would be due to angular momentum in the drives of the chair and the treadmill.
If there were also measurements on the floor then why not test the braking that way too? I am not surprised your calculations do not agree with what the treadmill measurements imply. When motor car brakes are tested on a rolling road, there is a force meter on the road itself and the car is held stationary. That gives the correct result without a road test. That is a totally different methodology.

 

[canucks]

Is there a way that I can verify the data?

 

[sophiecentaur]

Is there a way that I can verify the data?

What do you mean by "verify"? If you want to find the retarding force from the chair motor / brake from the data you have then that could be a problem.
After all, if you disconnect hands and drive from the chair and stop the treadmill, the chair will be stationary with no effort on the part of the user. You could pull against the chair with a force meter with brakes applied or, which is much more relevant, you could measure stopping time and distance with very basic stopwatch and tape measure. When you get down to it, that's what you want.
A treadmill is a treadmill and it can give a measure of the dynamic performance of a runner or chair user (with or without motor). I don't believe there are any force measurements available from the treadmill (?) so you can't expect to use it to measure forces.
It's a shame that the experiment wasn't properly planned in a way to produce all the parameters you wanted. The results that were produced show as much about the stored momentum in the treadmill mechanism as anything else, I think.
I guess you'll tell me that the equipment is no longer available but, if it is, a few simple tests on a road will give you stopping distance.

 

[canucks]

I found this paper.. https://pdfs.semanticscholar.org/fb26/bcaf7cb5b4f5021c9232c2eda1f36c77ddaa.pdf in our case are we interested in Fx?

 

[canucks]

assuming, hypothetically stroke length is 100 degree

 

[A.T.]

I found this paper.. https://pdfs.semanticscholar.org/fb26/bcaf7cb5b4f5021c9232c2eda1f36c77ddaa.pdf in our case are we interested in Fx?

Are you asking us what you are interested in? According to your paper you are using an instrumented wheel, which measures the force applied to the rim.