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<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left><FONT size=2
face=Tahoma>-----Original Message-----<BR><B>From:</B>
robotics-bounces@blender.org [mailto:robotics-bounces@blender.org] <B>On
Behalf Of </B>Andy Mills<BR><B>Sent:</B> mardi 5 janvier 2010
21:52<BR><B>To:</B> robotics@blender.org<BR><B>Subject:</B> [Robotics]
Origami-folding robot<BR><BR></FONT></DIV>
<DIV>Hello,<BR><BR>I've decided to use Blender to model a robot/machine idea I
have, mostly because it already has the physics engine built in and the
soft-body objects look promising.<BR><BR>At this point, I have a model of what
I envision the robot to be like (some things are likely to change). However, I
have some quetions:<BR><BR>- It's not that important right now, but as it
stands, the robot is purely static objects, so no collsion. I notice that if I
apply physics to just one part, that part tends to fly away. Is it possible to
build an armature that's connected to a "static body" but the armature
controls a rigid body object? Will I have to create the whole thing as rigid
body? (There are some pieces that are stationary that I imagine could be
static.<BR>*Note, I don't think it's so necessary to have this answered by any
of you. I have a feeling I can find a tutorial or relevant info to this, but
any help would be appreciated.<BR><SPAN class=875164722-05012010><FONT
color=#0000ff size=2 face=Arial> </FONT></SPAN></DIV></BLOCKQUOTE>
<DIV><SPAN class=875164722-05012010><FONT color=#0000ff size=2 face=Arial>I'm
not sure what you mean by static/dynamic object. The normal way to do a robot is
to set an armature and parent a series of object to each bone to represent the
segment of the robot arms. These objects must be static because a rigid body
cannot be the child of anything. Static object doesn't mean no
collision. The robotic arm can interact with rigid bodies in the scene
but it will not get force feedback. To move the robot, set the armature
pose, either automatically with IK or manually by setting the bone
pose directly. There is an API in Blender 2.5 that simplifies the control
of the bones by allowing to set the joint angle (in Blender 2.49 you must set
the bone matrix).</FONT></SPAN></DIV>
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<DIV><SPAN class=875164722-05012010> </SPAN><BR>- Do any of you have
experience attempting to simulate paper, and manipulate it? Do you think the
soft bodies will be satisfactory? I'm really wondering if the soft bodies can
"keep a fold", like if you were to take a piece of paper, fold it in half,
then set it on a table with the fold up, like ^ whether it would maintain that
fold, but slowly lose it.<BR>I think I might end up being alone on this
one...<BR><SPAN class=875164722-05012010><FONT color=#0000ff size=2
face=Arial> </FONT></SPAN></DIV></BLOCKQUOTE>
<DIV><SPAN class=875164722-05012010><FONT color=#0000ff size=2
face=Arial>Unfortunately, Bullet Soft Body are not so useful. It is not possible
to have a folding effect, it is also very difficult to grab a soft body:
friction and plastic deformation are not properly implemented. Collision is also
poorly implemented: soft bodies tend to 'sink' through static object. You may
try to experiment with the various parameters but my own experiments have been
quite deceiving. </FONT></SPAN></DIV>
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<DIV><SPAN class=875164722-05012010> </SPAN><BR>- Another one I don't
necessarily NEED help on, but any insight might help. The game seems to play
just fine from Blender, but when I try to export a binary, it seems as if the
camera is facing away from the "scene." I haven't tried to set up controls for
the camera, yet, but I'm hoping that doing so will allow me to maneuver/focus
the camera on the scene (although I feel like it should be oriented as set up
in the scene/3D view. (I'm not sure if the camera is facing away or if the
objects aren't being drawn). Have any of you experienced this?<BR><SPAN
class=875164722-05012010><FONT color=#0000ff size=2
face=Arial> </FONT></SPAN></DIV></BLOCKQUOTE>
<DIV><SPAN class=875164722-05012010><FONT color=#0000ff size=2 face=Arial>When
running the game from Blender, any view point you have in the 3D view will
be converted in a temporary camera in the game. When running the game from
the binary, you can only use the real camera. To test the camera in
Blender, press 0 in the 3D view before running the game: this will put you
in the camera position and you will see the scene from the camera view
point. Fix its position if it doesn't point to the right
position.</FONT></SPAN></DIV>
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<DIV><SPAN class=875164722-05012010><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=875164722-05012010> </SPAN><BR>- As it stands, I'm not
currently using any sensors. At a minimum, I'm expecting to use some IR
sensors to ensure the paper's alignment, but I'm hoping I won't need very
sophisticated sensor systems. I've been looking at Pyro and Sirbot to satisfy
sensor simulation. What are you using?<BR><BR>I'm willing to share the .blend
file with you to get a better idea of what I'm talking about. Currently, the
robot is controllably only manually via keyboard.<BR><BR>Thanks in advance. I
hope not to be bothersome. If my project offers an opportunity, I hope to be
able to contribute to the robotics project.<BR><BR>I'm striving to "complete"
a thorough simulation within the next six months.<BR><BR>Regards,<BR><BR>Andy
Mills<BR></DIV></BLOCKQUOTE></BODY></HTML>