[Opensim-dev] robot simulation

Sat Mar 1 10:25:59 UTC 2008

For other interested developers:

We talk about this in the irc channel and the general conclusion (at least
the idea I got) is that it would be too difficult to add this kind of
functionality at present time.
OpenSim still have to catch up in features and openviewer is in its infancy.
Adding these features will potencially need changes in the client.
Openviewer is not there.

It may be the future and an eye should be kept on that but right now there
are other priorities.

Comments?

On Sat, Mar 1, 2008 at 2:35 PM, dan miller <danbmil99 at yahoo.com> wrote:

> --- Jordi <mumismo at gmail.com> wrote:
> > Hi,
>
> Welcome Jordi.  I do robotic simulation by day, and have been known to
> contribute to the physics plugins on nights and weekends.  I have goals
> very
> similar to your own.  A few points inline below.
> >
> > I am collaborating in the development of a robotic simulator (
> > http://playerstage.sourceforge.net/wiki/Gazebo).
> > I wanted to add a multiuser mode oriented to allow competitions.
> Searching
> > around I have found OpenSim.
>
> I used playerstage & Gazebo while doing robotics at CMU.  The simulator I
> work on at my day job is similar in some ways to PS/G (we considered using
> it but for various reasons developed our own).  A common element to all
> these projects is ODE -- it's the physics engine under Gazebo, my work
> code,
> and is by far the most developed engine for Opensim.  Unfortunately there
> are many issues other than just the physics engine to consider before
> undertaking an integration.
>
> >
> > I have being asking about this in the chat channel and basically OpenSim
> > lacks and needs to accommodate this kind of simulator at least the
> > following:
> >
> > - realistic physic simulation (IMHO
> > http://www.adrianboeing.com/pal/index.html is the way to go)
> > - sensors: cameras (multicameras), lasers, contact, gyroscopes,
> > temperature,
> > microphones, GPS , etc.
> > - joints, articulated bodies
> > - code to make articulated bodies move, reach etc using the joints and
> the
> > physic
> > - External interfaces so that programs can control all that (in their
> own
> > process without using scripting )
>
> Yep, that's what opensim would need, to be able to do the kind of
> simulation
> we're discussing here.  However, problems arise when you start to think
> about how the server and client components are architected.  Second Life
> is
> basically a gamer world; the physics is there to impart a sense of
> realism.
> However, most of what you see typically in SL involves scripting and
> animation, which often ignore physics completely.  Everything the server
> does has to be transmitted to each client over the internet, with variable
> delays, packet loss, etc.  The client is designed to try to produce an
> acceptable result in spite of these conditions.  The upshot is that the
> client frequently presents behavior to the user that is not exactly what
> the
> simulator is 'thinking', and is also not the same from client to client.
> The most obvious example of this is in avatar animation, which is
> basically
> a client-side script.  I'm still a bit unclear how server-side scripting
> really works, but I imagine it's basically streaming messages to the
> client
> about the position, velocity, etc. of each object ('prim' in SL
> terminology).  There is no provision in the client to understand things
> like
> linkages, wheels, etc -- the client is very dumb, it just tries to show
> things where they are supposed to be.  It also does some interpolation of
> velocity between messages, which can cause quite a bit of mischief.
>
> The good news is that this project is really in its infancy, and there is
> an
> opportunity to get involved in something that is still baking in the oven.
> The trickiest part will be to decide what can be done on the server side
> that will remain compatible with the Linden viewer, which will be the
> standard client-side application for the foreseeable future.
>  Alternatively,
> one could imagine extending the client side to do things more in line with
> a
> shared, deeply realistic simulation.  The OpenCroquet project seems to
> have
> been developed with this sort of thing in mind, but it's a research
> project,
> not something we've seen work in the real world (ie over the internet,
> with
> hundreds of users simultaneously).
>
> > What OpenSim has that our simulator lacks is :
> > - multiuser environment
> > - project visibility
> > - Tons of tools, models, etc
> > - Scripting
> > - good navigation system in the world
> >
> >
> > I am considering switching efforts to OpenSim but I want to know if
> > invasive
> > changes like those would be welcomed. Keep in mind that the simulation
> > will
> > be much more computer intensive. Also, maintaining the interfaces for
> > external programs can be tedious and get few users.
> > Also, it seems that OpenViewer is in an early stage of development. Some
> > of
> > those changes would need support from the client.
> >
> > Any comments welcomed.
> > Mostly: it would be welcomed? Anyone interested in helping with this?
> >
> well, I for one am very interested.  We can get into a deeper discussion
> of
> the technical challenges on IRC some time.  My moniker is danx0r.
>
> -dbm
>
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>

-- 
Jordi Polo Carres
NLP laboratory - NAIST
http://www.bahasara.org
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