how to use dJointSetFeedback(), and dJointGetFeedback()?
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ygz0515
Jun 26, 2009, 4:33:18 AM6/26/09
to ode-users
Hello，everybody，
I construct a wheeled mobile robot. Now, I need to get the
ground' reaction force to the wheels.
The forces include friction force in two directions on horizontal
plane, and support force in vertical direction.
The two directions of the friction are normal direction, which
is parallel to the rotation axis of the wheel, and tangential
direction, which is perpendicular to normal direction.
Since the wheel contacts the ground, there are contact joints
between them. So, I intend to use the dJointSetFeedback() to get the
contact joints' forces applied to the wheel, then the derived forces
are treated the ground' reaction force to the wheels.
I tried, but the derived result was not the same as expected.for
example, the support force should be constant, but it didn't.
Can anyone tell whether this method will do? if can, how to
realize. if not, can you suggest a good method to get the ground'
reaction force to the wheels?
dJointSetFeedback(), and dJointGetFeedback() should be used in
pair?
thank you.
I construct a wheeled mobile robot. Now, I need to get the
ground' reaction force to the wheels.
The forces include friction force in two directions on horizontal
plane, and support force in vertical direction.
The two directions of the friction are normal direction, which
is parallel to the rotation axis of the wheel, and tangential
direction, which is perpendicular to normal direction.
Since the wheel contacts the ground, there are contact joints
between them. So, I intend to use the dJointSetFeedback() to get the
contact joints' forces applied to the wheel, then the derived forces
are treated the ground' reaction force to the wheels.
I tried, but the derived result was not the same as expected.for
example, the support force should be constant, but it didn't.
Can anyone tell whether this method will do? if can, how to
realize. if not, can you suggest a good method to get the ground'
reaction force to the wheels?
dJointSetFeedback(), and dJointGetFeedback() should be used in
pair?
thank you.
Daniel K. O.
Jun 26, 2009, 11:30:31 PM6/26/09
to ode-...@googlegroups.com
ygz0515 escreveu:
> Since the wheel contacts the ground, there are contact joints
> between them. So, I intend to use the dJointSetFeedback() to get the
> contact joints' forces applied to the wheel, then the derived forces
> are treated the ground' reaction force to the wheels.
> I tried, but the derived result was not the same as expected.for
> example, the support force should be constant, but it didn't.
> Since the wheel contacts the ground, there are contact joints
> between them. So, I intend to use the dJointSetFeedback() to get the
> contact joints' forces applied to the wheel, then the derived forces
> are treated the ground' reaction force to the wheels.
> I tried, but the derived result was not the same as expected.for
> example, the support force should be constant, but it didn't.
As soon as you have a more or less complex system the feedbacks might
produce inappropriate values. The constraints solver doesn't care if the
forces are evenly distributed, as long as they produce the correct
result (that is, they add up to the proper force when they are all
applied to the respective bodies).
If that's what happening to you, see this thread:
http://groups.google.com/group/ode-users/browse_thread/thread/90f7d0228f903a51/0d216c0f772792e5?lnk=gst
--
Daniel K. O.
"The only way to succeed is to build success yourself"
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