[ODE] clock stepping and ODE

Jon Watte (ODE) hplus-ode at mindcontrol.org
Thu Nov 15 15:23:26 MST 2007

ODE uses a first-order integrator, and first-order response constraints. 
This means that time step variability will introduce energy in joints 
and contacts.

To solve the seeming discrepancy between real-time and stability, use a 
quantized main loop.



          / h+

Kevin Quigley wrote:
> On Nov 11, 2007 4:42 PM, Jon Watte (ODE) <hplus-ode at mindcontrol.org> wrote:
>> 3) To make a simulation stable, make sure that you're using a fixed time
>> step. Variable time step sizes, say based on the clock, will introduce
>> energy into the system.
> This was from the "sliding box on plane" thread earlier this week, but
> I was wondering what kind of instability using the system clock would
> generate?  The user's guide specifically mentions that "ODE is
> designed to be used in interactive or real-time simulation."  That
> implies that ODE will be able to use an outside clock in some fashion,
> although it shouldn't be variable stepping if you want to keep it
> real-time.
> Did I misunderstand something from the previous post?  I was hoping to
> use ODE on an RT system.
> quig

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