Controlling a Class of Nonlinear Plants Using Fuzzy Gain Scheduling and Qft

The work presented expands upon previous research into the uses of fuzzy gain scheduling (FGS). It combines FGS with the robust control design methodology, quantitative feedback theory (QFT). By combining FGS and QFT the advantages from both methodologies are achieved, namely the resulting controller synthesis methodology provides design transparency, because of QFT, and does not suffer from over design or from rapid open-loop variations, due to the FGS. This hybrid controller may be utilised to control a class of non-linear systems, where the plant may be expressed as a linear plant model with time varying parameters. The methodology for designing this hybrid controller is outlined by means of example. The example also experimentally compares a FGS with a simple QFT controller. The simulation results show that the hybrid FGS controller results in improved control over the plant, for little extra design effort.