SELF-ADJUSTING DIAGNOSTIC SYSTEM FOR THE MANUFACTURE OF CRYSTAL RESONATORS

In the development of a diagnostic system to monitor the condition of the frequency tuning process, fuzzy logic can be applied in recognitio n of unnatural statistical control chart patterns. The heuristics for reasoning is based on the principles behind statistical process contro l. With the experience of an expert in troubleshooting, one can derive the necessary knowledge to associate the pattern of a control chart t o a set of known physical causes. Since these causes related to the un natural statistical patterns are not independent, it is difficult to p recisely associate the chart distribution patterns to the known causes . Furthermore, the causes of problems dealt with will also vary with t ime. Hence, by means of neural networks, it is possible to learn the a ssociation of fuzzily deduced chart patterns to plausible causes in or der to achieve an optimum operating condition.