x-axis. Only the given specifications for control accuracy and experi-mental results were utilized to desi gn the MFs. Triangular MFs are verycommon in fuzzy systems because of their simplicity and ease of com-putation. MFs with evenly-distributed triangles with seven fuzzy lin-guistic variables were assumed, considering the desired control accu-racy with士0.5 °C at steady-state.The relationships among the control accuracy, fuzzy linguisticvariables, and maximum range of the MFs are represented in Eq. (2)[11].Cmarelimn-1(2)While elim refers to the allowable maximum error of the controlledvariables, chamber temperature and superheat, emax is the maximumrange of input variable e in the MFs and n is the number of fuzzy lin-guistic variables. In order to apply this equation, at least three condi-tions were assumed. First, the membership should be an evenly dis-tributed triangular shape. Second, the center of gravity (COG)arithmetic by Mamdani should be applied to calculate the crisp valuefrom the fuzzy membership value. Finally, the output linguistic variable