Theoretical Discussion on the Discrete-Time Feedback Error Learning for a Time Delay System with an Uncertainty Plant Model by using a PD Controller

In this study, a theoretical study on the discrete-time feedback error learning (DTFEL) method is discussed. The DTFEL method is developed because a digital controller is now replacing an analog one and the continuous-time feedback error learning (CTFEL) method is unable be to applied directly in the real systems. The DTFEL method shows a good tracking performance. However it can not work well in real system, since real systems include disturbance and uncertainty. This may cause the system to be unstable. For this reason, this study has considered the improvement of the controller in the feedback part to increase the robustness performance of the system. Consequently, the PD controller is applied to the feedback part for solving the robust stabilization problem and also to guarantee the stability of the system. Furthermore, this study implements the DTFEL system in a DC servo motor in order to check the validity on real applications.