Supervisory Control of Families Oflinear Set - Point Controllers - Part

| 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 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 , were the process's transfer function to be one of the subclass's members. In 1] it is shown that in the absence of unmodelled process dynamics the proposed supervisor can successfully perform its function fi.e., achieve a zero steady state tracking errorg even if process disturbances are present, provided they are constant. This paper proves that without any further modiication, the same supervisor can also perform this function in the face of norm-bounded un-modelled dynamics and moreover that none of the signals within the overall system can grow without bound in response to bounded disturbance and noise inputs, be they constant or not.