Hierarchical fuzzy control of the milling process with a self-tuning algorithm

This paper presents a hierarchical fuzzy logic controller (HFLC) with a self-tuning (ST) procedure based on pattern recognition of the closed-loop system response. A real-time tuning of the controller scaling factors is performed on the basis of the measured peaks in the error signal. In order to demonstrate the improved performance and effectiveness of this scheme, the ST-HFLC is applied to the end milling process. The response of the controlled process using the proposed controller (ST-HFLC), a standard HFLC and an HFLC with a self-regulating output scaling factor is analyzed. The ST-HFLC provides a better transient performance than the others. Without significant variation in rise time, a non-oscillating system with a short settling time can be achieved. These positive features, in the case of our particular application, may represent an increase of cutting tool life as well as the avoidance of chatter marks due to inappropriate cutting conditions.