Re: [simspark-devel] Increasing SimStep decreases the accuracy of position?

[Ben <lgp...@16...>]

Huang,
 
http://en.wikipedia.org/wiki/Physics_engine#Limitations
 
Regards
Ben


At 2010-12-09 19:32:31，"Huang Yaolong" <air...@gm...> wrote:
Hi, all.

I'm playing around simspark and change some standard parameters to do some testing.
Here is some changes I made:

setting the LinearDrag and AngularDrag of the Ball to 0.
changing the value of SimStep in SimulationServer from 0.02 to 0.1 and to 0.2.
setting the ball's initial velocity to (0, 0, 10),.
After making these changes, I found that with the smaller SimStep, the calculated position of the ball would be more accurate, but the velocity would be the same in all case.
For example, at the moment when simtime = 1.0, the position(initially(0, 0, 1)) and the velocity(initially(0, 0, 10)) of the ball is as follow(No agent connected):
SimStep   position          velocity
0.02        (0 0 5.9969)   (0 0 0.189999)
0.1          (0 0 5.6045)   (0 0 0.19)
0.2          (0 0 5.114)     (0 0 0.19)

As you can see, while the velocities being equal, the position tends to be smaller with the larger SimStep.

I don't what causes this difference. Is there any pointer to some references about this issue??

--
Best regards,
Yaolong Huang(Curtis)

Tianjin University, China

Blog:http://blog.csdn.net/airekans/