1 Introduction
ILC is a control technique applied to high performance systems which perform the same tracking task over a finite time horizon repetitively. The standard ILC framework can be considered as an open-loop feedforward methodology, which updates the input signal to improve the tracking performance by learning from the data of the previous executions (named trials). Unlike repetitive control, ILC has an initialization procedure at the end of each trial to reset the system states to the same initial values. ILC theoretically enables zero tracking error after sufficient historical trials, which is superior to traditional feedback control. Because of this key feature, ILC is applied to wide range of industrial tasks which require a high accuracy level, e.g. robotic systems [1], [2], chemical batch processing [3], [4] and stoke rehabilitation [5]. See [6] for a detailed overview of ILC.