Digital iterative learning control of compensated linear multivariable plants

It is shown that digital iterative learning controllers can be designed for irregular linear multivariable plants by introducing appropriate digital compensators. This demonstration is effected by proving a fundamental theorem which establishes precise sufficient conditions under which iterative learning control is achieved by such digital controllers and compensators in the case of first-order irregular plants. These general results are illustrated by the presentation of numerical results for the digital iterative learning control of a third-order partially irregular plant with two inputs and two outputs. The extension of the results to higher-order irregular plants is discussed.