How to constraint the lumbopelvic coordination?

Simon Jeng · Post by **Simon Jeng** » Thu Mar 31, 2022 10:55 pm

Hi all,

I expect that my skeletal model could include the lumbopelvic coordination. As the attached figures show, the orientation of the torso is T, the orientation of the sacrum is beta, the knee angle is K. The coordination expression is :
beta = -17.5 - 0.12T + 0.23K + 0.0012TK + 0.5T^2 - 0.00075K^2
How can I define this in OpenSim?

Thanks,
Simon