# Inverse Dynamics How to [closed]

I have some motion capture data (kinect) that records all body joints (32fps) and I want to take particular positions (for example when a person moves both of his hands up in the sky in celebration form) and find the forces that are being performed on each joint (or each bone). But what I really want is only the inside forces, the forces that the muscles perform, not gravity or wind or any other force. Can that be done using Open Dynamics Engine or Bullet. And if so, how? Is there a tutorial of some kind (I haven't found any yet)

EDIT-- The data that I currently have is xyz coordinates for each joint in each frame (as I said before 32 fps). It's easy to calculate the relative distance each joint made but what I need is the force applied to that joint and bone and maybe joint orientation if the force applied made the joint change orientation. I know that ODE and Bullet can take the dynamics of a 3D world (given by the programmer) and attach them to objects creating real world physics. What I need is to invert this process

-

## closed as too broad by Josh Petrie♦Jan 4 '14 at 17:32

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

Its newtons law of motion, F = ma, just mass multiplied with acceleration, acceleration is the change of velocity over time. Pretty straight forward math. Which part do you need help with? – Maik Semder Jan 13 '13 at 0:17
LOL, you are right :D What I need to do is take joint positions in time and return the forces that had been applied to each bone – John Demetriou Jan 13 '13 at 21:49
Yes and/or joint orientations, depending on what its gonna be needed for – Maik Semder Jan 13 '13 at 22:07
well simply finding the dynamics that made the bone move (or joint) but the whole point is I cannot find the weight of the bone to use what you told me above so I need another way. I will add more detail in the question for you on what data I have – John Demetriou Jan 14 '13 at 23:11
Those engines can only integrate the movements if they have a mass to work with, there is no way around it, you need the masses (or at least approximations) to calculate the forces from the movement – Maik Semder Jan 14 '13 at 23:47