释义 |
Infinitesimal RotationAn infinitesimal transformation of a Vector is given by
 | (1) |
where the Matrix is infinitesimal and I is the Identity Matrix. (Note that the infinitesimaltransformation may not correspond to an inversion, since inversion is a discontinuous process.) TheCommutativity of infinitesimal transformations and is established by theequivalence of
 | (2) |
 | (3) |
Now let
 | (4) |
The inverse is then , since
 | (5) |
Since we are defining our infinitesimal transformation to be a rotation, Orthogonalityof Rotation Matricesrequires that
 | (6) |
but
 | (7) |
 | (8) |
so and the infinitesimal rotation is Antisymmetric. It must therefore have a Matrix of the form
 | (9) |
The differential change in a vector upon application of the Rotation Matrix is then
 | (10) |
Writing in Matrix form,
Therefore,
 | (13) |
where
 | (14) |
The total rotation observed in the stationary frame will be a sum of the rotational velocity and the velocity in therotating frame. However, note that an observer in the stationary frame will see a velocity opposite in direction to thatof the observer in the frame of the rotating body, so
 | (15) |
This can be written as an operator equation, known as the Rotation Operator, defined as
 | (16) |
See also Acceleration, Euler Angles, Rotation, Rotation Matrix, Rotation Operator
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