Subject:
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Re: Robotic simulators
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 25 Apr 2005 06:09:11 GMT
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Original-From:
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dan miller <danbmil99@yahoo.com%ihatespam%>
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Viewed:
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878 times
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--- Steve Baker <sjbaker1@airmail.net> wrote:
[3D Lego simulator]
> We have talked about this for a while before.
>
> I think it's a very big problem to solve all of the physics stuff
> adequately
> at the brick-by-brick level. The visualisation doesn't give me quite so
> many
> worries (but then I work as a graphics programmer).
>
> The physics would be my big concern. I've used ODE before - and
> (regrettably),
> it's not the magic bullet you might think it is.
I'd be interested to hear about your experiences. The codebase I'm looking
at is called Gazebo (http://playerstage.sourceforge.net/gazebo/gazebo.html)
-- it sits on top of ODE, and seems to do a pretty good job of simulating
simple wheeled robots, at least.
> Whilst I'm sure you could build some sort of simulator - I'd be pretty
> sceptical about it's ability to predict the performance of a real Lego
> robot with any kind of fidelity.
I'm surprised to hear that. While obviously it wouldn't be perfect, it
seems to me that the granular, quantized nature of Lego parts would make
calculating the behavior of various linkages, gearing, etc. pretty
straightforward.
I'm not saying it wouldn't be a considerable undertaking; just that it seems
conceptually possible given the present state of the art in simulation
techniques. For the most part, Lego creations operate in a near-static
regime; you wouldn't have to worry about higher-order dynamic effects (in
other words, the inertia of parts is usually negligible compared to the
constraints the parts impose on each other... things aren't bouncing around
like in pinball machine.)
Connected blocks would be treated as rigid bodies. Almost all linkages are
what are called 'hinges' in ODE -- one degree of freedom around an axis.
Gears could be dealt with explicitly, or as wheels in contact with infinite
friction. Once the motor kicks in, the operation of the machine should
progress pretty much deterministically.
Anyway, seems like a cool idea. If anyone has a serious interest in this,
pls contact me -- danbmil99 at yahoo dot com
-dbm
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Message has 3 Replies:
 | | Re: Robotic simulators
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| (...) Sure. But that does not automatically lead to good results. I think you can be able to mimic the internals of a robot with some precision. Ah, you will limit your robot to some drive-and-seek robot, I think? I mean, you don't want to simulate (...) (19 years ago, 25-Apr-05, to lugnet.robotics)
| | | Re: Robotic simulators
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| (...) The thing I hate about ODE is that it doesn't like you giving it real-world units. If I have a little kart model (such as the demo model that comes with ODE), and it has a mass of about 1 unit, with appropriate spring stiffnesses, etc, (...) (19 years ago, 26-Apr-05, to lugnet.robotics)
| | | Re: Robotic simulators
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| (...) Dear Dan, I'm an Applied Mathematician/Physicist and have been to a couple of meetings where we take problems pozed by companies that can't solve them in-house. One set of these meeting is in Denmark and I was speaking to some people who were (...) (19 years ago, 26-Apr-05, to lugnet.robotics)
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