[ODE] Representing external simulation objects in ODE on atrajectory

[Delerue Jean-Francois]

Hello,

Would you have some good pointer to the theory on PID controllers or
some examples using it?

Thanks in advance,

Jean Francois

-----Original Message-----
From: ode-bounces at ode.org [mailto:ode-bounces at ode.org] On Behalf Of dan
miller
Sent: Tuesday, July 31, 2007 7:27 AM
To: ode at ode.org
Subject: Re: [ODE] Representing external simulation objects in ODE on
atrajectory

the method that seems to work best is to create a simple proportional
controller to move an in-world object.  It can be as simple as this:

Say your object is presently moving at velocity V0, and you want it to
move
at velocity V1.  set your force F = (V1-V0) * K, where K is a constant
you
figure out by trial and error (look up theory on PID controllers if
interested).

This approach will work as long as there's friction around to damp
potential
oscillations.  If not, you need to add a damping force, which would
typically be another constant times acceleration (ie difference between
present velocity and velocity at step t-1).

This sort of stuff is often in the game engine layers that are built on
top
of physics engines.  There might be a game engine that sits on ODE that
would help with this; otherwise, it's roll-your-own.

-dbm