Linear/Angular velocity (Analyzing Tool)

[Michala Cadova]

Hi,
From the Analyze tool I run the BodyKinematics, and I am now wondering, what results I got. For example in the file with the suffix “velocity” is written “This file contains the kinematics (positions and orientations, velocities and angular velocities, or accelerations and angular accelerations) of the centers of mass of the body segments in model workerModel.” For each body there are variables with suffixes “x, y, z, Ox, Oy, Oz” and then the “center_of_mass_x, center_of_mass_y, center_of_mass_z”. I assume that since this is the “velocity” file, I got the “linear velocity” (x,y,z) and the “angular velocity” (Ox, Oy, Oz). Is that right? What are the terms with “center_of_mass”? (Concerning the “center_of_mass” it is probably, as mentioned in the Getting Started with Analyses, “…the overall center of mass of the model, as well as the velocity and acceleration of this center of mass.”)
One more question – in the “acceleration” file, I got either zeros or “ -1.#IND0000”. What does that mean?

Thanks for any comments

Michala

[Ayman Habib]

Hi Michala,

Your interpretation of the results is correct.

I think the NaNs in acceleration are due to missing mass properties, do you have those specified in your model? If you believe the description on the support site below is not adequate please let us know so we can clear it up.
http://simtk-confluence.stanford.edu:80 ... h+Analyses

Best regards,
-Ayman