Convert Euler-Rodrigues vector to quaternion
Aerospace Blockset / Utilities / Axes Transformations
The Rodrigues to Quaternions block determines the 4-by-1 quaternion from a 3-element Euler-Rodrigues vector.
rod— Euler-Rodrigues vector
Euler-Rodrigues vector from which to determine the quaternion.
Quaternion determined from the Euler-Rodrigues vector.
An Euler-Rodrigues vector represents a rotation by integrating a direction cosine of a rotation axis with the tangent of half the rotation angle as follows:
are the Rodrigues parameters. Vector represents a unit vector around which the rotation is performed. Due to the tangent, the rotation vector is indeterminate when the rotation angle equals ±pi radians or ±180 deg. Values can be negative or positive.
 Dai, J.S. "Euler-Rodrigues formula variations, quaternion conjugation and intrinsic connections." Mechanism and Machine Theory, 92, 144-152. Elsevier, 2015.