[ODE] Newbie Question on Numerical Integration Method

[Piotr Obrzut]

Hi,

Monday, June 6, 2005, 9:11:18 PM, you wrote:

PO> Hi,

PO> 6 czerwca 2005 (19:10:54) Jon wrote:


JWO>> The ODE solver uses a first-order forward integrator; it cannot switch
JWO>> methods (as doing the LCP solver to a higher order would be 
JWO>> significantly harder...)

JWO>> If you have "wiggle" on resting bodies, the first thing to look at is
JWO>> your time step. You should be using a fixed time step, and step enough
JWO>> times to catch up to real time, but no more. The reason for this is that
JWO>> bodies "resting" in ODE really are continually falling into the ground,
JWO>> and getting a penalty force applied that pushes them out. If the time
JWO>> step varies, they fall different lengths each timestep, and get 
JWO>> different forces applied, which ends up causing instability.

PO> Right I also need very stable simulation and I'm using min and max
PO> steps count and when min == max then simulation is very stable, when
PO> min << max then it tends to explode. Still I have some problems
PO> with joint feedback forces: when min << max then they are very large,
PO> when min==max they are much lower but still they sometimes go to
PO> the large values. For me it is importand to have joint feedback forces
PO> on constant low level - anyone could help me with that?

Oh I forgot: by low feedback forces I mean that they should be very low when
in theory they should be 0



-- 
Greetings,
 Piotr Obrzut