A study on the robustness of a PID-type iterative learning controller against initial state error

In this paper, the effect of initial state error in the iterative learning control(ILC) system is studied. First, the previous result that the performance of D-type ILC algorithm can be improved by adding a P-term of error in the algorithm is generalized to PID-type algorithm. Then robustness is investigated against initial state error of the generalized ILC algorithm. It is also shown that the trend of error reduction can be effectively controlled by tuning gains of the proposed controller. In order to confirm validity of the proposed ILC algorithm, several examples are presented.