Hip joint center calculation in gait2392, where is the default hip joint center located?

[Madeline Grosklos]

How are the hip joint centers calculated for the gait2392 model if joint center kinematics are not provided?

For example, in Visual3D the hip joint landmarks for the CODA and Composite pelvis models are created using the Bell and Brand regression equations. (Bell AL, Pederson DR, and Brand RA (1989) Prediction of hip joint center location from external landmarks. Human Movement Science. 8:3-16: Bell AL, Pedersen DR, Brand RA (1990) A Comparison of the Accuracy of Several hip Center Location Prediction Methods. J Biomech. 23, 617-621.)

I cannot find any information on where the "default" hip joint centers ae located or how they are defined in the OpenSim gait2392 model.

I greatly appreciate any insights!

[Mohammadreza Rezaie]

Hi, the hip joint center is located in the center of the femoral head. This is also the origin of the femur geometry. So, just create a new marker, change the frame to femur_r and set the location to zero:

HJC.png (4.44 KiB) Viewed 319 times

Hope this helps.

[Madeline Grosklos]

Thank you Mohammadreza! This is helpful.

So, in order to understand the theory behind where the hip joint center is I would need to know the theory behind femur geometry, correct?

-Maddie