| 摘要 |
A method for adapting fuzzy reasoning to a change of a working environment of resistance welding without requiring a changing or updating of membership functions, thereby assuring optimal control and satisfactory weld quality. In an embodiment of the present invention, a welding current I and a change of resistance DELTA R across welding electrodes are measured during a welding operation. The number of welding operations N involving the welding electrodes is incremented. After the present welding operation, these values of DELTA R, I and N are offset by adding offsetting values delta DELTA R, delta I and delta N. Degrees of membership of respective antecedent membership functions are computed for the offset values ( DELTA R+ delta DELTA R), (I+ delta I) and (N+ delta N). Degree of membership of conclusion membership function of each control rule is computed from degrees of membership of its antecedent membership functions. Then degrees of membership of conclusion membership functions U, S and D is composed. From the composed degree of membership, an operation value i.e., percent change of preselected welding current is computed by the center-of-gravity defuzzification method. Finally, the preselected value of the welding current is corrected by using the percent change. The corrected preselected welding current is then used for the next welding operation.
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