A New Characterization of the Nyquist Stability Criterion.

摘要

The usual proof of the Nyquist Theorem depends heavily on the argument principle. The argument supplies unneeded information in that it counts the number of encirclements of -1. Stability of a system requires an encirclement or a no-encirclement test. Using homotopy theory, this paper offers a more intuitive approach. The authors believe this approach will lead to practical generalization, as for example, systems characterized by several complex variables such as multi dimensional digital filters. (Author)