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Tham khảo tài liệu 'computational intelligence in automotive applications episode 2 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Automotive Manufacturing Intelligent Resistance Welding 229 Table 8. Fuzzy logic controller rule-base Rule 1 If E is low AND N is low THEN di Pa 2 If E is medium AND N is low THEN di Ng 2 3 If E is high AND N is low THEN di Ng 4 If E is low AND N is medium THEN di Pa 2 5 If E is medium AND N is medium THEN di Ng 4 6 If E is high AND N is medium THEN di Ng 2 7 If E is low AND N is high THEN di Pa 4 8 If E is medium AND N is high THEN di Ng 8 9 If E is high AND N is high THEN di Ng 4 Fig. 7. Membership functions of the number of expulsion welds and the number of normal welds in a process window of the last p welds p is a fixed parameter . Parameter p defines a universe 0 p of the all possible expulsion and normal welds within that moving window the number of expulsion and normal welds in the last window of p welds through a set of rules with fuzzy predicates Table 8 . In the rules of the fuzzy logic controller low medium and high are fuzzy subsets defined on the 0 p universe for the number of expulsions E and the number of normal welds N Fig. 7 . Ng 0 and Pa 0 are constants fuzzy singletons defining control changes of the current. The first three fuzzy rules deal with the case where the number of normal welds N in the last window is low. Based on the number of detected expulsions three alternative strategies for changing current level are considered If the number of expulsions is low it is reasonable to think that the state of the welds is close to the cold welds status. Hence it is necessary to increase gradually the amount of current i.e. the current is changed by. di Pa. If the number of detected expulsions is medium or high it is reasonable to think that the state of the welds is close to the expulsion state. Hence it is necessary to decrease the amount of current. This is performed selectively based on the number of expulsions high vs. medium resulting in negative changes of the current di Ng vs. di Ng 2. When the number of normal welds N in the process window .
