2015 Volume 28 Issue 4 Pages 127-132
In spacecraft attitude control, the quaternion is often used as a kinematic parameter, simply because it has no singularities. In the tracking problem of an attitude control, the error quaternion is needed for quaternion feedback. Due to complexity of the quaternion math, the error quaternion is sometimes misunderstood and its incorrect denition is used for attitude control. Even in such cases, the tracking objective is achieved to some extent. In this paper, we consider attitude control of a spacecraft with RWs and examine the property of the error quaternion.