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Invers Kinematics of upside down Motion Capture data

Posted: Wed Aug 14, 2024 3:27 am

by lucybuchanan

Hi,

I am using the Inverse Kinematics tool on some data collected with Vicon. In some of the movements, the subject goes upside down (e.g. handstand) and the body position appears completely wrong (bent knees and flexed hips rather than roughly a straight line). When using this tool for walking, jumping and squatting there are no issues. I am using the LaiUlrich2022 model.

Any suggestions as to why this might be happening would be great.

Thanks,
Lucy

Re: Invers Kinematics of upside down Motion Capture data

Posted: Wed Aug 14, 2024 8:00 pm

by aafox

Hi Lucy,

This might be due to the allowable motion for pelvis rotation, list and tilt. I've had similar issues where the pelvis could only rotate 90 degrees yet it needed to go 180 degrees as a participant was moving in the opposite direction to usual. IK then fits as best it can within the allowable joint coordinate range and the model becomes disfigured looking. My guess is that your pelvis tilt coordinate doesn't have a large enough range for the model to completely flip upside down.

Aaron