A Cross-Coupled Iterative Learning Control Design for Precision Motion Control

This paper presents an improved method for precision motion control by combining individual axis iterative learning control (ILC) and cross-coupled ILC (CCILC) into a single control input. CCILC is a new method in which a multi-axis cross-coupled controller (CCC) is reformatted into a single-input single-output (SISO) ILC format. Applying the techniques of ILC to CCC enables learning of the cross-coupled error which leads to a modified control signal and subsequent improvements in the contour trajectory tracking performance. In this paper, performance of the combined ILC and CCILC system is compared to standard feedback control through computer simulations and experimental testing on a Cartesian robotic system. Sufficient stability and convergence properties for the combined system are presented along with a modified approach for determining monotonic convergence of systems that are computationally challenging. The combined design is shown to enhance the precision motion control of the robotic system through performance improvements in individual axis tracking and contour tracking.