Annotation marker

I am recently using AMMRV2.1 to import C3D files for sports biomechanical analysis. I would like to ask you a few questions while using it.

  1. I would like to ask where the speed of the human body is in the chart? Because what I find is the speed of a part of the human body, not the speed of the whole human body.
  2. Since I only do lower extremity simulation, I use the existing lowerextremity.any. Because only the lower limbs are marked during the test, I want to comment out the parts of the torso and head, but this problem occurs when annotating and fitting. How can this problem be corrected?

Best Regards.

Hi Xu,

  1. Speed of the human body depends on how you define the speed. I am not sure if we have a standard definition of how to extract the speed of the whole human body but I maybe wrong. If you have some specific ideas of how to measure the speed of the whole human body, I can try to help you. Otherwise, I could suggest that you can look at the speed of the center of mass of the human body (Main.HumanModel.BodyModel.Interface.CenterOfMass). Alternatively, you could look at the speed of the pelvis as an approximation of the speed of the human body.

  2. Unfortunately, we don't have a standard model with only the lower limbs. I will suggest some things with the assumption that you are interested in lower limbs and and you have force plate data. In the marker protocol file you can comment out all the upper body markers that you don't have. This will leave the trunk and the head totally unconstrained. You can then add the weak mannequin drivers to drive these degrees of freedom. Please find the "ExtraDrivers.any" file through your LabSpecificData.any file and add these lines:


You will need to add more of these weak mannequin drivers for the other degrees of freedom. You can see a list of the define statements in the AMMR documentation page.

What this will do is just make the model kinematically functional. These degrees of freedom will be driven to zero. Of course, this will not be a natural motion but it should not matter since you have force plate data and the human ground residuals will be acting on the pelvis.

I hope this helps

Best regards,

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