Forward-Inverse Dynamics mismatch
Posted: Thu Oct 14, 2010 2:42 pm
Hi,
I'm working on the simplified both leg model with no muscles for analysis of the standing posture using contacts at the feet. I first calculate the forces using inverse dynamics and then using the obtained forces simulate the system in forward dynamics. However, the leg model is unable to maintain its balance during the forward dynamics simulation. It would be helpful if one can clarify the following:
1. Does inverse dynamics take into account the unknown contact forces that might occur during the simulation?
2. In what coordinate frame does the result (forces and moments) appear in the output of the inverse dynamics analysis?
3. For forward dynamics when I apply loads (forces and moments obtained from inverse dynamics) on the bodies in the system, I am also required to explicitly specify the kinematics of the loads. Can I use the loads obtained from the inverse dynamics as Prescribed forces (assuming they happen to be in the body fixed frame) with a synthetic kinematics of the loads (specifying every coordinate to be zero in the file) to reproduce the same motion?
Thanks.
Regards,
Priyanshu
I'm working on the simplified both leg model with no muscles for analysis of the standing posture using contacts at the feet. I first calculate the forces using inverse dynamics and then using the obtained forces simulate the system in forward dynamics. However, the leg model is unable to maintain its balance during the forward dynamics simulation. It would be helpful if one can clarify the following:
1. Does inverse dynamics take into account the unknown contact forces that might occur during the simulation?
2. In what coordinate frame does the result (forces and moments) appear in the output of the inverse dynamics analysis?
3. For forward dynamics when I apply loads (forces and moments obtained from inverse dynamics) on the bodies in the system, I am also required to explicitly specify the kinematics of the loads. Can I use the loads obtained from the inverse dynamics as Prescribed forces (assuming they happen to be in the body fixed frame) with a synthetic kinematics of the loads (specifying every coordinate to be zero in the file) to reproduce the same motion?
Thanks.
Regards,
Priyanshu