Robust design method using adjustable control factors

Design that ensures robust performance for diverse users and environments has received much attention. Previous research proposed a Robust Design Method (RDM) that considered the adjustable control factors (ACFs) of mechanisms such as the servo mechanisms of machine tools or recliner mechanisms of public seats. This method derived the optimum adjustment ranges of the ACFs only after both these factors and their (dependent or independent) relationships had been identified in the design problem. This research improves on the previous RDM to enable designers to select ACFs and their relationships. This method contains two indices. One is the standard deviation of each control factor, used for finding ACFs that need not be adjusted. The other is the contribution ratio of the eigenvalues calculated from the variance-covariance matrix of the ACFs, used for finding dependent relationships. This method effectively derives the optimum adjustment ranges of the ACFs and their relationships based on these indices. Numerical and design examples are presented to demonstrate the practicality of the proposed method.