Hi David,

The set of collision libraries that we are currently using are based
on ODE. They will tell you when the arm is in collision with the
object and they can also give you a sense of how far the arm is
penetrating inside the object. However, they won't give you distance
to nearest obstacle. We are working towards libraries that will give
you that information but we don't expect that to be done for a while.

There are some tools that might be useful for you though. One is in
the distance_field package and it lets you create a 3D distance
transform that can give you distance to the nearest obstacle. It is
expensive to compute though and typically we compute it out to a small
finite distance only. It is used in the chomp_motion_planner right now
(and other places as well).

If you do know the full trajectory - as we do in the motion planning
pipeline - you can check it easily and figure out the first point in
collision.

Hope this helps.

Best Regards,
Sachin


On Thu, Jul 15, 2010 at 6:23 PM, David Lu!! <davidvlu@gmail.com> wrote:
> Are there any calls in the collision detection libraries to figure out the
> closest vertices are in a model?
> For example, if an arm is moving toward an obstacle, but the full trajectory
> to the obstacle has not yet been calculated, is there a call that says the
> arm is close to the obstacle and/or likely to collide with it?
> -David!!
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-- 
Sachin Chitta
Research Scientist
Willow Garage