Re: [Pyode-user] holding an object at a certain level with a chain

[Ethan Glasser-C. <gl...@cs...>]

Sorry Nick for the duplicate mail..

nick knouf wrote:
> I have a rectangular box (mostly in the xz plane) with 4 chains in  
> the +y direction, attached with ball joints on the corners of the  
> box.  I want to use the chains to hold the box above the floor.

How did you build chains using ODE? (This is personal curiosity; the
most effective chains I've been able to build have been hinge joint +
slider, but that's only in 2D.)

> Pseudo-code for the holding algorithm (in both cases described above)  
> is as follows:
> 
> currentVelocity = finalChainElement.getLinearVel()
> currentPosition = finalChainElement.getPosition()
> desiredPosition = holdPosition
> 
> desiredVelocity = desiredPosition - currentPosition
> desiredAccel = desiredVeclocity - currentVelocity
> finalChainElement.addForce(holdingMass * desiredAcel + holdingForce)

I'm not sure but this looks like you should be using some kind of
motor instead of computing forces like this.

Ethan