Multi-stage fuzzy PID controller with a fuzzy switch

Use of a multi-stage fuzzy logic controller (MSFLC) is explored for PID feedback control. This approach blends a proportional-plus-derivative fuzzy logic controller (PDFLC) with an integral fuzzy logic input. The multi-stage structure operates on fuzzy values by passing the consequence of a prior stage onto the next stage as fact. The resulting controller gives excellent results which are further improved by intelligently adjusting the rule matrix for the PDFLC