Re: [ompl-users] Planners return colliding paths

[Boris L. <la...@in...>]

sorry, forgot to cc the list...

-------- Original Message --------
Subject: Re: [ompl-users] Planners return colliding paths
Date: Thu, 24 Mar 2011 16:36:29 +0100
From: Boris Lau <la...@in...>
To: is...@gm...

Hi Ioan,

thank you very much for your quick reply.

My understanding of the resolution is this:
I can simply choose to map the grid space coordinates to the continuous
space 1:1. Therefore, I use 0 and the width/height (whatever is bigger)
of the map as manifold bounds. Then I need a maximum stepsize of 1 cell,
therefore 1/extent.
And indeed, when I print out which cells are checked for collisions,
they are indeed either adjacent, or the algorithm is jumping somewhere else.

> Could it be possible this distance is less than 1, but the cells are not
> adjacent?
I think that's a no. But I tried it anyway, 0.5/extent, same results.

> Let me know if this does not work, and some pictures of the erratic
> paths may be helpful.
Here are pictures of RRT and KPIECE1 paths. Each step in the path is one
picture, frame by frame:

http://www.informatik.uni-freiburg.de/~lau/generated_paths.zip

As you can see, the RRT returns a very sparse but valid path, and the
KPIECE1 does something weird. The only thing I change is using either
    ss.setPlanner((ompl::base::PlannerPtr)(new og::RRT(si)));
or ss.setPlanner((ompl::base::PlannerPtr)(new og::KPIECE1(si)));

The rest is as in the simple setup example. Do I need to setup a
projection thing myself?

> cell dimensions for the default projections are of appropriate size
> (some tuning may be required).
>
> std::vector<double> dims(3);
> dims[0] = 1;
> dims[1] = 2;
> dims[2] = 0.1;
> ss.getStateManifold()->getDefaultProjection()->setCellDimensions(dims);

When I use these lines I get an error:
terminate called after throwing an instance of 'ompl::Exception'
what():  Number of dimensions in projection space does not match number
of cell dimensions

So, I tried the same with just 2 dims, no error, but same results as before.

> Instead of this:
>  > ss.setPlanner((const ompl::base::PlannerPtr)new og::RRT(si));
> do this:
> ss.setPlanner(ompl::base::PlannerPtr(new og::RRT(si)));
I did, no difference. Valgrind is completely happy.

Thanks again for your help.
And by the way, my colleague Christoph Sprunk says hi, you've met at the
BRICS labor camp.

Best, Boris

-- 
Boris Lau

Albert-Ludwigs-University Freiburg
Institute of Computer Science, Autonomous Intelligent Systems Group
Georges-Koehler-Allee 079, D-79110 Freiburg, Germany

Building 079, Room 1005
Phone: +49 761 203-8012 | Mobile: +49 174 9436758
http://www.informatik.uni-freiburg.de/~lau