# [ODE] Arbitrarily positioning bodies connected by joints

Eike Decker eike at cube3d.de
Mon Jul 23 04:40:48 MST 2007

```I have the same problem and would be interested in a solution, but have not done
any research on this topic due to other problems.

Eike

> Have I asked the question poorly?
>
> I can't imagine that nobody here has ever tried to *move* a
> collection of bodies connected by joints.
>
> In the past, I've just assembled things on the fly at the position
> and orientation I want them to start at, but it seems very useful to
> me to be able to build something at one place, and then arbitrarily
> transform it later.
>
> shamyl at zakariya.net
>      "obviously, you're not a golfer"
>          -- the Dude
>
>
> On Jul 17, 2007, at 10:44 AM, Shamyl Zakariya wrote:
>
> > I'm interested in being able to move a set of bodies connected by
> > arbitrary joints. That is to say, I want to be able to assemble them
> > at, for example the origin, and then move the whole thing to some
> > arbitrary position and orientation later. For example I might
> > assemble a "car" and then move it to where I want it to go.
> >
> > I'm able to move all the bodies retaining their positions in relation
> > to one another. But, unfortunately, the joints go bonkers to varying
> > degrees. The best behaved is the ball joint, which ( I guess )
> > considers its position to be relative to the parent. But other
> > joints, such as hinge and slider seem to freak out a little.
> >
> > Just to clarify, when I move the bodies I zero out all forces on
> > them. I've verified that if I move a bunch of bodies that aren't
> > connected by any joints they *do* retain their relative positions
> > correctly. So the issue is that the joints don't seem to enjoy being
> > suddenly moved/oriented.
> >
> > My current approach is simply to not do anything to the joints, and
> > assume (hope) that ode considers their attachment points in the
> > coordinate systems of the bodies they connect. But as I've described,
> > this doesn't really work. I've considered destroying the joints,
> > performing the move, and the re-creating them, but this may change
> > their zero-points since a connected system ( two bodies connected by
> > a "servo", for example ) may have moved before I positioned it.
> >
> > Any suggestions for me?
> >
> > Shamyl Zakariya
> > 	- hobo-raconteur
> >
> >
> >
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>
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