that's the kind of problems that I claim the inverse dynamics solves, if you want to get an accurate measure of the acceleration the invDynamcic was designed for that.
It will gives accurate joint force and toque, and the net body accelerations.
try looking at the demos, you will see they are not that hard follow.
believe, over the year I have read some many papers that the large majority of what the do is to solver for that, and I am still yet has not found one that does it right. this is simply because the problem is a close system. we have it, you might a well using it.
Hmm... i might confuse inverse dynamics with IK, but here is why i'm not using it:
1. Currently, using just one joint and two bodies, it's overkill and there should be no need for it.
2. To use it for a ragdoll, i can do so only by using effectors at the ends of a chain. Thus i lack precise control of internal bodies, which means i can't control the COM of the entire ragdoll, so i could not use my balance controller at all.
Besides COM control i expect further limitations from the effector approach. E.g. lacking control over the spine, which is all internal.
My own IK solver gives me all those options, but making it react to dynamics is extra work, and wont be as good as yours.
I've said this before, but is there some kind of middle ground that i miss?
Til yet i always was happy with using joint motors.