ABSTRACT
In this chapter, a multilevel fuzzy control (MLFC) system is developed and implemented to deal with the real-world nonlinear plants with intrinsic uncertainties and time-varying parameters. The MLFC strategy has a hierarchical structure with an adaptation mechanism embedded in the lower level to tune the output membership functions (MFs) of the first layer fuzzy controller and can be used to control a system with an input–output monotonic relationship or a piecewise monotonic relationship. The stability of the resultant closed-loop system is theoretically proven in both continuous and discrete domains. A series of simulations carried out on different uncertain nonlinear systems are shown to demonstrate the effectiveness of the proposed control method in the presence of unknown external disturbance and model parameter variation. Finally, experimental implementation results of the MLFC are shown for a creep-feed grinding process and an end-milling process to maintain a constant force and achieve a maximum metal removal rate (MRR).
