[ODE] ground reaction force

[Max Lungarella]

Thanks a lot David.

I opted for your first suggestion, which seems to work properly ...
well, almost: calling dJointGetFeedback outside of nearCallback causes a
SegFault (yes, I do initialize all pointers :) Hence I had to resort to
a quick and dirty "hack". If I call dJointGetFeedback in nearCallback
(right after dJointSetFeedback) the SegFault disappears, everything's
fine, and I get my sensory feedback.

I don't like it this way, but it seems to do the job.

Thanks a again for the hint.

Bests,
	Max 


> Ground Reaction force:  Let's see, I would say the best way to do this
> would be, in your nearCallback, save a list of all the contacts that
> have the ground as one of the geoms.  Then when you get finished with
> the collision detection, set up feedback struct for each contact joint
> (see section 7.2 of docs).  Run the step, and it will fill in the
> feedback struct for each of the joints.
> 
> Same thing for the analog touch sensor, except check to see if either
> of the geoms has a sensor "attached" to it.
> 
> As far as exact implementation goes, it would probably be easiest to
> set up an object that includes values for whether the geom is part of
> the ground, has a sensor attached, and a pointer to the sensor object,
> and set that as the data parameter for each geom at the start
> (dGeom[Set/Get]Data()).  Then you could put a feedback object in your
> sensor class, and just send its address directly to dJointSetFeedback
> in the collision code.
> 
> Hope that helps,
> David
> 
> > hi all,
> >
> > what is the best way to measure the ground reaction force, that is
> > the vertical component of the force exerted by the ground on a body
> > in contact with it?
> >
> > a second related question is: what is the best way of realizing a
> > analog touch sensor?
> >
> > thanks a lot for any type suggestion.
> >
> > cheers,
> > 	max
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> 
> 
> 
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-- 
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Max Lungarella
Neuroscience Research Institute
AIST Central 2, Umezono 1-1-1
Tsukuba 305-8568, JAPAN
max.lungarella@aist.go.jp
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