Adaptive Control of Milling Forces under Fractional Order Holds

This paper introduces a novel discrete-time modelreference based control of the tool-work-piece interaction force in a milling process. The novelty of the scheme relies on the use of a fractional order hold (FROH) instead of a traditional zero order hold (ZOH) used in the manufacturing literature to obtain a discrete-time model of the continuous system. The additional degree of freedom introduced by the FROH through its correcting gain allows the designer to improve the closed-loop behavior of the time-varying unknown system by an adequate choice of its value. Simulation examples showing the influence of the correcting gain in the closed-loop response are presented and compared.