This paper presents a five-phase taxonomy of systematic procedures to enable flexibility in the design and management of engineering systems operating under uncertainty. The taxonomy integrates contributions from surveys, individual articles, and books from the literature on engineering design, manufacturing, product development, and real options analysis obtained from professional e-index search engines. Thirty design procedures were classified based on the kind of early conceptual activities they support: baseline design, uncertainty recognition, concept generation, design space exploration, and process management. Each procedure is evaluated based on ease of use to enable flexibility analysis, whether it can be used directly in collaborative design activities, and has a proven applicability record in industry and research. The organizing principles integrate the procedures into a cohesive and systematic design framework. Demonstration applications on engineering systems case studies show that it helps designers select relevant procedures in different phases of the design process, depending on the context, available analytical resources, and objectives. In turn, the case studies show that the design framework helps generate concepts with improved lifecycle performance compared to baseline concepts. The taxonomy provides guidance to organize ongoing research efforts, and highlights potential contribution areas in this field of engineering design research.
