Search results
Results From The WOW.Com Content Network
A direct formula for the conversion from a quaternion to Euler angles in any of the 12 possible sequences exists. [2] For the rest of this section, the formula for the sequence Body 3-2-1 will be shown. If the quaternion is properly normalized, the Euler angles can be obtained from the quaternions via the relations:
The Euler angles are three angles introduced by Leonhard Euler to describe the orientation of a rigid body with respect to a fixed coordinate system. [ 1 ] They can also represent the orientation of a mobile frame of reference in physics or the orientation of a general basis in three dimensional linear algebra .
3D visualization of a sphere and a rotation about an Euler axis (^) by an angle of In 3-dimensional space, according to Euler's rotation theorem, any rotation or sequence of rotations of a rigid body or coordinate system about a fixed point is equivalent to a single rotation by a given angle about a fixed axis (called the Euler axis) that runs through the fixed point. [6]
The quaternion formulation of the composition of two rotations R B and R A also yields directly the rotation axis and angle of the composite rotation R C = R B R A. Let the quaternion associated with a spatial rotation R is constructed from its rotation axis S and the rotation angle φ this axis. The associated quaternion is given by,
These coordinates have an elegant description in terms of quaternions. Any unit quaternion q can be written as a versor: = = + where τ is a unit imaginary quaternion; that is, a quaternion that satisfies τ 2 = −1. This is the quaternionic analogue of Euler's formula.
The equation presented for conversion from Euler angles to Quaternion has several discontinuities that are not necessarily present in the Quaternions themselves. For instance, for the Euler angles (0,0,-180) and (0,0,180), the conversion would produce the quaternions (0,0,0,1) and (0,0,0,-1).
This explains why, for example, the Euler angles appear to give a variable in the 3-torus, and the unit quaternions in a 3-sphere. The uniqueness of the representation by Euler angles breaks down at some points (cf. gimbal lock), while the quaternion representation is always a double cover, with q and −q giving the same rotation.
The angle θ which appears in the eigenvalue expression corresponds to the angle of the Euler axis and angle representation. The eigenvector corresponding to the eigenvalue of 1 is the accompanying Euler axis, since the axis is the only (nonzero) vector which remains unchanged by left-multiplying (rotating) it with the rotation matrix.