Supervisory control of families of noise suppressing controllers

This paper describes a high-level "supervisor" capable of switching into feedback with a single-input/single-output (SISO), linear time-invariant (LTI) process a sequence of linear controllers, so as to suppress from the output of the process the effect of a persistent disturbance input consisting of the sum of a finite number of sinusoids of unknown amplitude, phase, and frequency. Each of the controllers being supervised is designed so as to solve the disturbance rejection problem for a specific set of disturbance frequencies. The stability results stated in this paper are valid when the frequencies of the disturbance sinusoids are known to belong to a finite set.