On Thu, 17 Apr 2003, Christopher Parker wrote:
> I want to log data about things other than robots. Specifically,
> I am doing some work on multiple robot box pushing. I want to track the
> position of the box. Originally, I thought that I would make the "box" a
> position device and set the friction to and mass to appropriate levels,
> but it turned out that I couldn't set the friction on a position entity.
> So, now I am using a large heavy puck as my "box", but I don't know how I
> can log its position, since I don't think that I put a truth device on a
> puck (or if I could, how I would get the data from it). Thanks.
Actually, you can put a truth (or gps) device on a puck. For example:
puck( color "red" pose [5.113 7.404 0.000] truth( port 7000 ) )
In this case, you would connect to port 7000 and read the truth data.
However, you should know that Stage is a strictly kinematic simulation, and
does not include any dynamics. In particular, the way in which the pucks are
moved around is an *extremely* simple approximation of Newtonian physics, and
should not be considered to be a good model of how real pucks (or boxes)
behave. You'll surely notice, for example, that the pucks stick to walls,
rather than bouncing off them. Having said that, I'm interested to hear (and
maybe see movies of?) how you do in simulating box-pushing.
If you're interested in a realistic simulation of box-pushing, and of
manipulation capabilities in general, you'll want to look into the Player/Stage
project's next big thing: Gazebo. Gazebo is a 3-D simulation built on a proper
dynamics engine. Importantly, it will be a drop-in replacement for Stage,
exposing the familiar Player interface (but able to simulate far smaller
populations than Stage). Gazebo is currently in development, and I don't know
the projected timeline; talk to Andrew Howard (he's on this list) for more info
and access to pre-releases.