Output feedback invariants Original Research Article

The paper is concerned with the problem of determining a complete set of invariants for output feedback. Using tools from geometric invariant theory it is shown that there exists a quasi-projective variety whose points parameterize the output feedback orbits in a unique way. If the McMillan degree ngreater-or-equal, slantedmp, the product of the number of inputs and number of outputs, then it is shown that in the closure of every feedback orbit there is exactly one nondegenerate system.