Discrete-time adaptive control of milling forces using fractional order holds by on-line adjustment of the correcting gain

Increasing industrial competence suggests to develop and implement more complex control strategies in manufacturing environments for achieving better performance requirements. In this paper, a multi-estimation scheme for adaptive discrete control is applied to a practical milling system in order to minimize process and machine malfunctions. The different models of the scheme to be estimated are obtained from a set of a continuous unknown milling system transfer function under a fractional order hold of correcting gain beta isin [-1,1] (beta -FROH) . The objective is to design a scheme which is able to find the best value for the gain beta within a predetermined set in order to generate the real control input to the plant. A tracking performance index evaluates the tracking error and the scheme chooses the one with the smallest value has at each multiple of the residence time.