# Instantaneous centres of rotation

1. Oct 11, 2006

### Fermat

Anyone know a good web site, or two, that will tell me about working out the instantaneous centre of rotation; for links only I imagine.

TIA.

2. Oct 14, 2006

The first thing that came up on google []: http://www.fsid.cvut.cz/en/U2052/node27.html. Not much, depends on how deep you need to get into it.

By the way, if I recalled it correctly, if you know the speed $$\vec{v}_{A}$$ of a point A, and the angular speed $$\vec{\omega}$$, then you can find the speed of any point B with $$\vec{v}_{B}=\vec{v}_{A}+\vec{\omega}\times \vec{r}_{BA}$$, where $$\vec{r}_{BA}$$ is the vector from A to B. The condition on the centre of velocity is $$\vec{v}_{B} = \vec{v}_{c} = \vec{0}$$, so you can find its position.

Last edited: Oct 14, 2006
3. Oct 14, 2006

### Fermat

Many thanks.
I found a site (eventually - it took me ages, even on google) that told me what I was supposed to do. I used Kennedy's theorem to find the IC's and worked things out from there.
It was faster the first way I did it though. I just resolved velocities at the link ends and worked my way through the mechanism. Instantaneous centres gave the same answer, but took longer