Robust Design of Digital Dynamic Systems by the Bayesian Point Estimation Method

Problems where the output varies depending on the input (signal factor levels) are classified as dynamic systems in the Taguchi method. In dynamic systems, if both input and output have only two digital values (0 and 1) with the possibility of committing two types of errors (judging 0 as 1 and 1 as 0), such a problem is called digital system or digital-digital dynamic system. In the digital system, whenever an input signal is 0 or 1, the output is affected by control factors and noise factors, the criterion for judging the output is the threshold value R. If output is smaller than threshold R, output is set as 0 when input signal is 0. Similarly, if output is larger than threshold R, the output is set as 1 when input signal is 1. Hence, two types of error rate are occurred. The purpose of this paper is to apply the Bayesian point estimation method to view the error rates as random variables and optimize the digital system and find the setting value of threshold R for the cases of loss coefficients are unequal. The implementation and the effectiveness of the proposed approach is illustrated through a case study.