[ODE] Joints flying off?

Karl Meissner karl at meissnersd.com
Fri May 30 06:00:02 2003


Thanks, that helps a lot. I thought anchor was in body coordinates... 
The pole now move correctly if there is a single body.
but....
I still run into situations where the joints 'break'.  If I drop a the bodies
into a pile eventually (after about 5 or 6 ) one of the poles 'breaks' and falls off. 
Maybe the contacts overwhelm the hinge code? Seems like a bug....

--- "Martin C. Martin" <martin@metahuman.org> wrote:
> My guess is you're setting the anchor in the wrong place.  You need to set
> it, in world coordinates, to the location where the pole meets the box
> (assuming that's where you want the hinge to be.)  Come to think of it,
> you also need to set the hinge axis properly, in the world coordinate
> frame.
> 
> - Martin
> 
> Karl Meissner wrote:
> > 
> > Hi I am new to ODE so I might be making a newbie mistake.
> > 
> > I am trying to set up a simple situation.  I want to have a 1x1x1 square cube that has a 1
> meter
> > pole attached  to the center of its top face.     The problem I have is that the pole’s bottom
> > does not stay attached to the cube....it drifts away after collisions.
> > 
> >  I create the cube and pole,
> >   set their positions so the bottom of the pole just touches the cube
> > create a hinge
> > attach the two bodies to the hinge
> > 
> > Then I run the sim.    The cube and pole drop down and hit the ground and then the pole drifts
> > away. Visually the pole is affected by the cube but it does not keep its bottom in a fixed
> > relative position.
> > 
> > Also, if I don’t set the anchor point, the bodies spin like mad.
> > 
> > I have tried setting the various joint parameters such as CPM to 1 or 0 and the stop
> parameters.
> > These seem to help somewhat but still the pole does not stay attached.
> > It is particularly bad if I create a bunch of these bodes and cause them to collide with each
> > other.
> > 
> > So I guess my question is there a way to attach a joint so the pole will not 'drift'.
> > Is it some combination of hinge parameters?
> > 
> > Karl
> > 
> > __________________________________
> > Do you Yahoo!?
> > Yahoo! Calendar - Free online calendar with sync to Outlook(TM).
> > http://calendar.yahoo.com
> > _______________________________________________
> > ODE mailing list
> > ODE@q12.org
> > http://q12.org/mailman/listinfo/ode


__________________________________
Do you Yahoo!?
Yahoo! Calendar - Free online calendar with sync to Outlook(TM).
http://calendar.yahoo.com