[ODE] Simulating a Cylinder.

Keshav kbc at dhruva.com
Thu Aug 22 23:15:02 2002


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Hello,
 
I was trying to simulate a cylinder using ODE.
 
I'm using the standard ODE capped cylinder geometry object.
And, I'm using a "plane" object as my ground or floor.
 
I drop off the cylinder from a small height.
 
Everythings fine, until the cylinder touches the floor plane.
As soon as it touches the floor, it vanishes.
When I check it's position, it shows as NAN (not a number).
 
When I add global ERP, say 0.5, then, the cylinder stays for about 2
seconds after hitting the ground, and then, it disappears.
 
My cylinder's physical parameters are:
    Radius: 1.13
    Length:  0.6
    Mass:    10
 
I kept radius and length the same, and increased the mass to 1000.
Now, surprisingly, the simulation was very stable.
 
But, I noticed this -> since my cylinder's radius is much larger than
it's length, the cylinder should actually be resting on the 
flat side, i.e on the caps, isn't it?
Later, when I went through the documentation again, it says that, there
are two half-spheres as caps for the cylinder.
Is there anyway of creating a cylinder with flat caps, instead of half
sphere caps?
 
How can I simulate a cylinder (with flat caps at both ends) using ODE
successfully?
 
Has anybody simulated a cylinder (with flat caps at both ends) using
ODE?
 
- Keshav.

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<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial=20
size=3D2>Hello,</FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>I was trying to simulate&nbsp;a cylinder =
using=20
ODE.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>I'm using&nbsp;the standard ODE&nbsp;capped =
cylinder=20
geometry object.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>And, I'm using a "plane" object as my ground =
or=20
floor.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>I drop off the cylinder from a small=20
height.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>Everythings fine, until the cylinder touches =
the floor=20
plane.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>As soon as it touches the floor, it=20
vanishes.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>When I check it's position, it shows as NAN =
(not a=20
number).</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>When I add global ERP, say 0.5, then, the =
cylinder=20
stays for about&nbsp;2 seconds after hitting the ground, and then, it=20
disappears.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>My cylinder's physical parameters=20
are:</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>&nbsp;&nbsp;&nbsp; Radius:=20
1.13</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>&nbsp;&nbsp;&nbsp; Length:&nbsp;=20
0.6</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>&nbsp;&nbsp;&nbsp; Mass:&nbsp;&nbsp;&nbsp;=20
10</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>I kept radius and length the same, and =
increased the=20
mass to 1000.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>Now, surprisingly, the simulation was very=20
stable.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>But, I noticed this -&gt; since my cylinder's =
radius is=20
much larger than it's length, the cylinder should actually be resting on =
the=20
</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>flat side, i.e on the&nbsp;caps,&nbsp;isn't=20
it?</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>Later, when I went through the documentation =
again, it=20
says that, there are two half-spheres as caps for the=20
cylinder.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>Is there anyway of&nbsp;creating a cylinder =
with flat=20
caps, instead of half sphere caps?</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>How can I simulate a cylinder (with flat caps =
at both=20
ends) using ODE successfully?</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002>Has anybody simulated a cylinder (with flat =
caps at=20
both ends) using ODE?</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN><SPAN=20
class=3D960482107-13082002><FONT face=3DArial size=3D2><SPAN=20
class=3D111145714-14082002></SPAN></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D960482107-13082002><FONT face=3DArial size=3D2>-=20
Keshav.</FONT></SPAN></DIV></DIV></BODY></HTML>

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