Strange spikes in output data

Hi,

I am using the new anymocap model (from GitHub) with AnyBody v.7.0.1. My experimental setup is a leg press performed using a flywheel exercise device. I have motion and force data in a C3D-file as input and the model works fine when I run it. However, when looking at the output data in the chart window there are spikes on certain intervals and I can’t figure out what they originate from or how I can get rid of them. They can be seen in the output of Pmech and MaxMuscleActivity for example and I think they originate from the trunk somehow. I have a traction force attached to the trunk, but if I am plotting that force there are no matching spikes explaining the strange behavior in the aforementioned outputs. I would be very grateful if somebody could help me figure out what the problem is!

Kind regards,
Maria

Hi

i have tested the model and found the following:

1 : The RASIS marker seem to drop out and move strangely, it should be fixed in data or excluded.
2: By looking at Thorax.rDDot you can see that the spikes comes from kinematics…

So inspect markers for dropouts and ensure segment acc has no spikes.

Best regards
Søren

Hi Søren,

Thanks for your answer! Actually, I was pretty sure I had already excluded the RASI marker but obviously (and embarrassingly) not… As you said, that was the problem and the results look all fine.

However, I have more trials that I will add to my model later on and some of them have 2-3 markers dropping out in different parts of the trial. I thought adding the following code to my C3DSettings.any file would solve the problem (or at least smoothen the transition) with marker drop outs:

GapFillUsingResidualsOnOff = On;

Have I misinterpreted the function of that bit of code?

Kind regards,
Maria

Hi Maria,

This setting will fill the gap using an interpolation function, but if the gap is too big it will nok make a good result, it is only intended to fill small gaps.

Best regards
Søren

Ah, ok. Then I understand.

Thanks for your answer!

Kind regards,
Maria

One more thing … it is ok to use GapFillUsingResidualsOnOff for large gaps if the markers weight is set low in these periods, please see https://github.com/AnyBody/anymocap/blob/master/Examples/SpecialFeatures/MarkerWeightsExample.main.any#L41
The GapFillUsingResidualsOnOff can be used to ensure there are no “edge artifacts” when the markers comes and goes…

Best regards
Søren