[ODE] moment of inertia
Dan Riley
dpriley at ucla.edu
Mon May 20 20:55:02 2002
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ok im just starting to build articulated body dynamics into a program im =
writing, however, i would like to build the engine myself ( i like to =
know exactly how everything works in the program and would like to =
custom tailor it to what i already know and want), however, my phsyics =
skills are not the best (im a sophomore in college studying design). =
I've read through featherstone's "robot dynamics algorithms" but If some =
of you could answer some of the following questions that would be great.
I'll start off with some simple ones:
moment of inertia:
the rigid bodies in my program are all just blocks with uniform density. =
from what I understand, this should mean that the moment of inertia =
matrix for each body should be as follows:
Ixx =3D (m/12)*(height^2+length^2)
Iyy =3D " *(length^2+width^2)
Izz =3D " *(height^2+width^2)
matrix is then
{ Ixx, 0 , 0 ,
0 , Ixy, 0 ,
0 , 0 , Ixz}
is this correct?
do you guys mind if I ask more questions?
Dan
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<DIV><FONT face=3DArial size=3D2>ok im just starting to build =
articulated body=20
dynamics into a program im writing, however, i would like to build the =
engine=20
myself ( i like to know exactly how everything works in the program and =
would=20
like to custom tailor it to what i already know and want), however, my =
phsyics=20
skills are not the best (im a sophomore in college studying design). =
I've read=20
through featherstone's "robot dynamics algorithms" but If some of you =
could=20
answer some of the following questions that would be great.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I'll start off with some simple =
ones:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>moment of inertia:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>the rigid bodies in my program are all =
just blocks=20
with uniform density. from what I understand, this should mean that the =
moment=20
of inertia matrix for each body should be as follows:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Ixx =3D =
(m/12)*(height^2+length^2)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Iyy=20
=3D " =20
*(length^2+width^2)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Izz =3D =
" =20
*(height^2+width^2)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>matrix is then</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>{ Ixx, 0 =
, 0=20
,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2> 0 , =
Ixy, 0=20
,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2> 0 , =
0 , =20
Ixz}</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>is this correct?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>do you guys mind if I ask more=20
questions?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Dan</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV></BODY></HTML>
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