Alternatives of Taguchi's Approach for Dynamic Robust Design Problems

Robust Design is an important method for improving product quality, manufacturability, and reliability at low cost. Most research in robust design has been focused on problems with static responses. This paper deals with the robust design problems with dynamic responses. The objective of the paper is to investigate and compare three modeling approaches: the loss model, the response function model, and the response model approaches. Taguchi¹⁶ proposes the loss model approach which models the loss measures as functions of the control factor effects. Miller and Wu¹⁰ propose the response function model approach which models the loss measures as functions of the effects of both control and noise factors. Tsui¹⁸ proposes the response model approach which directly models the response as a function of the effects of control, noise, and signal factors. In this paper, we identify and derive the relationships between the effect estimates of the three approaches and show that the loss model approach creates unnecessary biases for the factorial effect estimates and may lead to non-optimal solutions. The three modeling approaches are compared in a real example.