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How do I upload a file. I have some pertinent quaternion/vector related material.
nhughes1ster@gmail.com.
2009-05-12 01:30:35 UTC in mjbWorld
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Remember, a quaternion, a rotation matrix (a direction cosine matrix), a set of three Euler angles, actually each Euler angle individually, merely represent A ROTATION. Whether the particular rotation is relative to the inertial frame, the pilot's frame or the frame of your dog's food bowl, is up to you. There is nothing inherent in a rotation or its representation that implies what frame it...
2008-10-22 01:47:08 UTC in mjbWorld
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Screws and twists in space are not standard mathematical nomenclature. You may have a software package that defines them in some specific manner but it is non-standard. As you have described these concepts, they appear to be very complicated, non-intuitive and very difficult to use. If recommend you investigate the use of quaternions, direction cosine matrices (rotation matrices - the 3 X 3...
2008-09-06 04:22:19 UTC in mjbWorld
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I just looked at your web page with the 4 X 4 matrix representing rotation and translation. You go through an example where you demonstrate that two translation vectors in the right column of the matrices add correctly. However, you do not have any rotation in this example. If the upper 3 X 3 of either matrix were not the identity matrix, the translations would not come out right. As I have...
2008-09-06 04:12:27 UTC in mjbWorld
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I'm sorry. I can't follow what you're trying to do. If you are grabbing an object with your mouse, you have a software application that has its own characteristics. If you want to deal with rotations mathematically, please read the attached paper and use quaternions. And, again, there is no inherent relationship between rotation and translation!!!!!! A mechanical constraint (a door hinge...
2008-09-06 03:53:26 UTC in mjbWorld
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Rotation and translation are, in general, completely independent of one another. Thus a formulation that describes rotation does not "take into account any translation". If there are constraints and/or a mechanism that couples rotation and translation, then the two are related. For example, when an airplane rotates in pitch, the angle of attack changes which increases or decreases...
2008-09-06 03:02:05 UTC in mjbWorld
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Nicolas,
I'm glad I was able to help clear things up for you. You're right that you can do two, or any number of, successive rotations about the same axis. However, in the Euler angle world, this is a singularity, the dreaded "Gimbal Lock" of Apollo 13 infamy. When two Euler angle axes are aligned, you have only two degrees of freedom and bad things happen. Take a model airplane...
2008-05-01 22:40:33 UTC in mjbWorld
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The coordinate system I described is a RIGHT handed system! Thinking of an airplane, X forward through the nose, Y out the right wing - when you cross X into Y - fingers of the right hand start at X and curl into Y - your thumb is DOWN. If this software package uses a coordinate system as you describe and forces you to use only Euler angles, I hope you didn't pay good money for it. I...
2008-02-29 14:27:49 UTC in mjbWorld
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Are you using the standard aerospace definitions of heading, attitude and bank angles? This convention defines the heading, or yaw, angle as the first rotation, about the +Z or vertical down axis, the attitude, or pitch, angle as the second rotation about the +Y or the "out the right wing" axis and roll as the third rotation about the +X or the "out the nose" axis. If so...
2008-02-28 23:15:31 UTC in mjbWorld
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what software package are you using that only allows you to point your camera with Euler angles?
Noel Hughes.
2008-02-28 23:00:43 UTC in mjbWorld
