On the transformation of time-variable systems to the phase-variable canonical form
Bellamkonda Ramaswami, K. Ramar · IEEE Transactions on Automatic Control · 1969
The problem of transforming a single-input single-output time-variable linear system to the phase-variable canonical form has been considered. A simpler method of finding the transformation matrix is presented. Also, a different proof is given to show that uniform controllability is a necessary and sufficient condition for a nonsingular transformation to exist.