Analyze tool analysis results that look VERY wrong

[Bahar Sharafi]

I've come across the following issues using the Analyze tool:

1) I am using PointKinematics analysis to calculate the trajectory and velocity of a point on the heel. While the poistion looks quite reasonable, the velocity printed to the _vel file is not in any way the derivative of the position (figure below, position in red and velocity in blue).

2) The actuation force obtained from the kinematic analysis has no similarity to the actuation force obtained from CMC, even though the actuation analysis was performed using the CMC state file from the same simulation.
Example actuation force from Actuation Analysis:

rect_fem_r_actuationAnlysis_actuation_force.png (8.73 KiB) Viewed 540 times

Actuation force from CMC:

rect_fem_r_CMC_actuation_force.png (10.57 KiB) Viewed 540 times

3) Similarly the moments obtained from muscle analysis are bizarrely unrealistic numbers in the thousands while the moments seem reasonable (O(cm)).

Anyone else ever run into a similar problem?

[Ayman Habib]

Hi Bahar,
There are many settings for the AnalyzeTool that may affect the results as you observed (e.g. compute_equilibrium for muscle states, are grf's applied? Are residuals applied? what controls are used?). To make sure you have a full state it'd be better to run the analyses along with CMC run, but if that is not feasible, please make sure all inputs (model, grfs, additional actuators if any) are identically specified in CMC and AnalyzeTool.

If that seems to be the case please file a bug report with all files needed to reproduce the behavior and we'll investigate.

Best of luck,
-Ayman

[Bahar Sharafi]

Hi Ayman,

Thanks for your reply! You are definitely correct, when I run the analyses within CMC, the results look just fine, both for the kinematics and muscle analysis.

Bahar