Tuning of fuzzy controller for an open-loop unstable system: a genetic approach

The design, test and evaluation of an optimised fuzzy logic controller (OFL C) is reported in this paper. With the aid of genetic algorithms (GA), the rule-base of an otherwise standard fuzzy logic controller (FLC)is obtained. This is achieved by deriving a tailor-made encoding scheme, initialisation , crossover and mutation of rule table into strings of integers. GA is impl emented such that the existing knowledge of the system is utilised to incre ase the speed of optimisation. The OFLC is successfully applied to control an open-loop unstable system - the ball-and-beam balance system - on a hard ware test-bed. A Kalman filter controller (WC) and a manually tuned fuzzy l ogic controller (MFLC) are also developed for the test-bed and the performa nces of the three controllers are compared. The experiment reveals that imp roved robustness with shorter design cycle can be achieved by integrating G A into an FLC. (C) 2000 Elsevier Science B.V. All rights reserved.