IEEE Transactions on Automatic Control, Vol.42, No.11, 1500-1515, 1997
Supervisory Control of Families of Linear Set-Point Controllers .2. Robustness
A simply structured high-level controller called a "supervisor" has recently been proposed in [1] for the purpose of orchestrating the switching of a sequence of candidate set-point controllers into feedback with an imprecisely modeled single-input/single-output (SISO) process so as to cause the output of the process to approach and track a constant reference input, The process is assumed to be modeled by a SISO linear system whose transfer function is in the union of a number of subclasses, each subclass being small enough so that one of the candidate controllers would solve the set-point tracking problem, if the process’ transfer function was to be one of the subclass’ members, In [1], it is shown that in the absence of unmodeled process dynamics the proposed supervisor can successfully pei form its function (i.e., achieve a zero steady-state tracking error) even if process disturbances are present, provided they are constant, This paper proves that without any further modification, the same supervisor can also perform this function in the face of norm-bounded unmodeled dynamics and moreover that none of the signals within the overall system can grow without hound in response to bounded disturbance and noise inputs, whether they are constant or not.