Combined ILC and DOB for Repetitive Control with Application to Fast Tool Servo System

Fast tool servo (FTS) systems using piezoelectric technology show great promise for ultra-precise machining due to their high precision and responsiveness. However, during machining, these systems often struggle with tracking accuracy due to factors like system complexity and external disturbances. To address this, we propose a robust control method specifically for piezo-driven FTS. Our approach aims to improve tracking accuracy and disturbance rejection during machining. We use a robust repetitive control scheme with a disturbance observer (DOB) to minimize the effect of interference on tracking. However, in practice, solving the inverse model of the controlled object can introduce uncertainty. To enhance the disturbance observer’s performance, we add iterative learning control (ILC). This helps refine control actions based on past errors, improving overall system performance.