Discrete-type repetitive control method and an apparatus therefor

摘要

A discrete-type repetitive control unit which enables stable repetitive control even if a state variable of a controlled object is not observable, using time delay elements (Z.sup.-1). The number of time delay elements is equal to or greater than a value obtained by dividing a cycle period of a cyclic target input by a period of sampling the deviation between a controlled object output and the cyclic target input. Periodically applied to each of the time delay elements is a sum obtained by adding the product of the deviation and a first gain (h1, - - - , hn) associated with the time delay element, to the product of an input (u(k)) of the controlled object and a second gain (m1, - - - , mn) associated with the time delay element, and to an output (Wn(n+n), - - - , W1(k+1)) of a preceding element. The control unit periodically applies to the controlled object a sum (u(k)) obtained by adding the product of the deviation and a third gain (h0) to an output (W1(k)) of the last time delay element. The control unit achieves a stable operation of the controlled object with the flexibility to respond to variation in the cycle period of the target input and without causing a delay in following the target input which periodically changes in a single changing pattern.