Rigid body dynamics question

  • Thread starter alextex
  • Start date
  • #1
2
0

Main Question or Discussion Point

Hi!
I have been working on a rigid body subject quite a long. But till now there is an unresolved question for me. When we calculating the torque acting on the rigid body we use the following definition of the torque: t = r X f, X - is a cross product. So if I calculate the torque in a body-fixed system I use r in the body-fixed system too, but for force f - I am not sure. In which coordinate system should it be expressed - in the body-fixed or in space-fixed. Are this forces different in both systems? Sorry, for probably stupid questions. Thanks
 

Answers and Replies

  • #2
2
0
Sorry, I've found - we really need to do all in the same coordinate system.

But now, I have some other question - probably, more interesting. The torque acting on the rigid body (expressed in the body-fixed frame) is given by: t = -0.5*S(q)*(dU/dq), gde U - potential, q - is a quaternion, ans S(q) - is a matrix such that: dq/dt = 0.5*S(q)w, where w - is a 4-dimensional angular velocity. Can anybody explain how to get that formula for the torque?
 

Related Threads for: Rigid body dynamics question

  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
4
Views
4K
Replies
5
Views
751
  • Last Post
Replies
4
Views
2K
Replies
1
Views
663
  • Last Post
Replies
5
Views
1K
Replies
1
Views
850
Top