pyode-user

[Pyode-user] ropes, in ODE.

[Simon W. <sim...@gm...>]

I want to simulate a rope in ODE.

I am using a hinge joint, to constrain the rope to the z axis.

I attach one end of the rope to the environement, and the other end to
a body. In between the environment and body are 10-15  bodies, which
make up segments of the rope. These are all joined using HingeJoints.

The simulation seems to work for a few seconds, but after that, the
rope goes nuts. It seems that the joints stretch apart then bounce
back, causing the rope to go a little epileptic.

Any ideas on how to do a better rope simulation? I am new to ODE, so I
may have missed something.


-Sw.

[Pyode-user] Re: ropes, in ODE.

[Simon W. <sim...@gm...>]

On 1/17/06, Simon Wittber <sim...@gm...> wrote:
> I want to simulate a rope in ODE.

I've made the simulation much better, by reducing the world.step time
to 0.01, and iterating it 10 times. It's killed my performance though.

[Pyode-user] Re: ropes, in ODE.

[Simon W. <sim...@gm...>]

On 1/17/06, Simon Wittber <sim...@gm...> wrote:
> On 1/17/06, Simon Wittber <sim...@gm...> wrote:
> > I want to simulate a rope in ODE.
>
> I've made the simulation much better, by reducing the world.step time
> to 0.01, and iterating it 10 times. It's killed my performance though.
>

Problem solved. I added more mass to the rope segments, and the
simulation stabilised.

Re: [Pyode-user] Re: ropes, in ODE.

[Matthias B. <ba...@ir...>]

Simon Wittber wrote:
>>> I want to simulate a rope in ODE.
>> I've made the simulation much better, by reducing the world.step time
>> to 0.01, and iterating it 10 times. It's killed my performance though.
> 
> Problem solved. I added more mass to the rope segments, and the
> simulation stabilised.

Does it really look like a rope? A hinge can freely rotate around its 
axis, so I'd expect such a "rope" rather to look like a chain. Did you 
do any special stuff to get it more "rope-like"?

- Matthias -

Re: [Pyode-user] Re: ropes, in ODE.

[Matthias B. <ba...@ir...>]

Simon Wittber wrote:
>> Does it really look like a rope? A hinge can freely rotate around its
>> axis, so I'd expect such a "rope" rather to look like a chain. Did you
>> do any special stuff to get it more "rope-like"?
> 
> Well, it does look more like a chain than a rope. I not really
> satisfied with the results yet.

You could try adding some friction to the hinges. This can be done by 
activating the motors. Set the target velocity to 0 and the maximum 
force to a relatively low value (higher values = more friction). I could 
imagine that this already improves the look of the rope.

- Matthias -