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Hello every Opensim users,
When I did IK or scale, the pelvic position flipped as shown in attachments which was quite confusing to me.I checked the row data in Vicon which was fine and tried to delete the four marks of the pelvis.Then I ran IK again,the pelvic position still fliped shown in the second picture.I would really appreciate it if anyone could tell me why or give me some advice.
Yours sincerely,
Li Lyo

please compare the experimental marker and the virtual marker one by one to make sure that the experimental markers' name and position corresponds to the virtual marker.

also you can check if markers are applied to correct bodies

Hi Li,

You also might want to check the coordinate limits on the pelvis rotations. I recall having some issues with some data that the participant was facing the opposite way to what OpenSim expected, and the pelvis rotation about the vertical axis was limited to 90 degrees either way. The result of this was that the participant model could not completely turn around to match the data, and required putting larger bounds on the pelvis rotation coordinates.

Aaron