Question

Which of the following is a four element entity consisting of a scalar and a vector and is used to describe strapdown system rotation?

(a) Directional cosines

(b) Directional sines

(c) Quaternion

(d) Triternion

I had been asked this question during an interview for a job.

The query is from Strap Down and Gimballed Inertial Navigation Systems topic in portion Satellite Radio Navigation  & Inertial Navigation of Avionics

Answer 1

The correct option is (c) Quaternion

For explanation I would say: Describing rotation motion in the strapdown system employ more than the minimum three parameters. A quaternion is a four element entity ting of a scalar part and a vector part. It defines the instantaneous axis of rotation.