/sci/ - Science & Math

I'm trying to find the work done by the motion constraint of the 4-bar linkage system(pic related).
[math]W_{motion} = \tau_{motion, torque}\Delta\theta_O[/math]
I ran it in a simulation so I know the angles and angular velocities of all the components, but I'm not sure how to set the equation up, or what [math]\tau_{motion, torque}[/math] is really referring to.