Fuzzy Logic Based Dryer Controller

Abstract

The relative humidity sensor changes its capacitance with the humidity. The humidity sensing circuit is constructed around a 555 timer with astable operation. It produces a rectangular wave. In order to achieve the perfectively symmetrical square wave as well as to reduce the frequency value, CD4017BC that is divided by 10 Johnson counter with 10 decoded outputs and a carry out bit is added to the timer’s output. The resultant frequency is applied into the computer system integrating with the fuzzy logic. Fuzzy Logic determines the frequency value and its rate of change which are input to the fuzzy logic control system that determines the real world constraint of the dryer's heating rate to the dryer driver circuit which is constructed with the pulse width modulation (PWM) technique. Input and output operations to and from the computer system are carried out via parallel interfacing and Turbo C++ programming.