Deterministic lead/lag compensator and iterative learning controller design for high precision servo mechanisms

Abstract

This research focused on the controller design for a high precision servo mechanism. An XY table powered by two DC servo motors was used as a test bed for the control algorithms. Firstly, a new simplified lead/lag compensator design was used. The advantage of this design over existing ones was the ability to develop an explicit expression of the controller for a given phase margin. This design could be performed with only knowledge of the frequency response of the plant. To improve performance, ILCs (Iterative Learning Controllers) were used to compensate for the non-linearities. Previous cycle learning (PCL), current cycle learning (CCL) and the hybrid version - previous-current cycle learning (PCCL) mechanisms, were used to update the learning process. Robustness of these controllers against parameter variations, uncertainties and non-linearities was studied.