Quote:
Originally Posted by Brandano
Hmm, I presume it's a method to estimate attitude by integrating inertial platform data via accumulation of quaternion transforms, if the quaternions mentioned are the same used in animation data in 3D software. Essentially a quaternion is a way to represent a rotation around an axis by defining the axis ( I think as a vector with origin 0 pointing pointing towards a set of x, y and z coordinates, like a normal, but its length is not important in this application) and a rotation from the original position (I believe the most used standards define the rotation as an amount in radians, positive if clockwise when seen from the origin of the rotation vector, negative otherwise). The advantage of a quaternion when compared to a simple matrix transform is that it allows for accumulating rotations greater than 360° without ambiguity as to the rotation direction, and makes it possible to interpolate intermediate steps between animation keyframes. The disadvantage is that it only stores rotation data, no translation data or scale data.

Well put. In the terms of attitude estimation, it actually can require less computational power than DCM (direct cosine matrix). And that ambiguity in a DCM can cause gimbal lock, which can render an aircraft uncontrollable.