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csu-hmc / perturbed-data-paper

A paper on an elaborate gait data set.
https://peerj.com/articles/918/
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Check the sign and convention of the ankle angle and torque #51

Closed moorepants closed 9 years ago

moorepants commented 9 years ago

I think that Ton's code defines the nominal standing position to have a -90 angle. Can't remember the plantar and dorsi flexion conventions from that code.

moorepants commented 9 years ago

I wonder if I should plot a line from Winter's data over mine (after normalizing).

tvdbogert commented 9 years ago

Yes, about -90 during standing, but standing is not used as a reference. I checked the code. Ankle angle is defined as the angle between the line connecting the shank markers and the line connecting the foot markers. Column 7 of the "segments" table changes the sign so the counterclockwise rotation (dorsiflexion) would be positive.

There are various sign conventions and zero conventions in the literature. This is as good as any. We may need just a brief summary of this in the Methods. The determined reader can always find the exact definitions in the code.

If superimposing the Winter data makes us look good, why not... It's easy to get differences though, due to different test conditions, marker placement etc. and if that is an issue just don't compare so you don't need to explain.

moorepants commented 9 years ago

Ok, yes. Everything is correct in the current diagram. Thanks.