Extensions of the frame alignment technique and their use in the characteristic locus design method

Abstract Frame alignment, performed by the ALIGN algorithm, plays an important role in the characteristic locus design method. A number of extensions to ALIGN intended to enhance the effectiveness of the design technique are proposed. In particular, the application of ALIGN at a number of frequency points is considered while an alternative least squares approach to frame alignment is developed. The problem of scaling both the frames to be aligned as well as the resulting frame solutions is examined and procedures for optimizing the use of the approximate commutative controller technique are suggested.