The idea of band-wise compensation is extended to the design of parame
tric model-based controllers. Given an (LTI) unknown plant and a frequ
ency domain specification, one first choses a frequency set where the
open-loop compensation is required. Then, for each frequency band, one
represents the plant by a lower- (first- or second-) order transfer f
unction, and designs a band-compensator. This procedure allows the red
uction of a high-dimensional problem (pole placement, LQG, etc.) to a
set of lower-dimensional problems, avoiding the problem of singularity
arising in most adaptive control by using the certainty equivalence.
A numerical example is included to illustrate this idea.