inverse dynamics

[jalfonsosm]

Hello,

This is a post that I put in bullet forum. Now, I'm studing the possibility of use Newton for my project since I read that Newton use forces instead of impulses to solve the contacts. Is this true? Can someone help me with the next questions?

Thanks a lot.



I'm trying to compute the inverse dynamics of a biped (hybrid dynamics) and I have a lot of questions. Could someone help me with some information?

Well, I know that I can use recursive Newton Euler or Lagrangians Dynamics. But since I don't know how to compute the matrix that contains the Coriolis and Centripetal terms, I'm using RNEA. What are the best papers that explain Lagrangina dynamics and how to compute this matrix?

Another question is how to compute the inverse dynamics problem when the biped is in the double stance phase. Since in this phase I have to solve a closed loop (I'm not sure if this is always true, since I think that it's depend of the contact model used in the simulation). Lagrangian method solve this problem?

For the forward simulation, I don't know what is the best approach. I prefer use PGS method like Bullet or LCP method like ODE, but I've found implementations where penalty based methods are used. So I don't know if the algoritmh may change depending of the model contact used by the simulator, for contacts Bullet use impulses not forces.

Can I use PD controllers instead of compute the correct torque to get the desired joint angles taking into account the ground contact forces? Exist a good alternative to avoid use inverse dynamics and get good results?

Thanks in advance and sorry for my bad english

[Julio Jerez]

If you have so much doubts maybe it is better you continue using some other engine.
Perhaps Netwon is not for you.

[JernejL]

I can't but notice that none of your questions are actually about newton except the first one. I think newton uses forces to solve contacts but i'm not sure.

The rest of questions belongs to something like.. here: http://www.physicsforums.com

Also as Julio said, this isn't a place to ask for comparison to other engines. You can get newton engine with sources - try it, look how it works and what methods it uses and see if it fits your needs.