Domain Mapping Matrix-Based Metric for Measuring System Design Complexity

Modern engineering systems are increasing in complexity and demanding higher levels of performance, safety, durability, and quality. This has led to an increase in the number of functional requirements and system elements. Subsequently, meeting the target performances and schedules requires more design effort and cost. To ensure on-time development and delivery of the final system, engineers need to allocate the right amount of available resources to design and develop various subsystems. However, estimating the efforts required to design and develop a system and its constituents during the early design stage is significantly challenging. Often, initial estimations are made by subject matter experts who base their judgments on the perceived difficulty of designing the subsystems. In this article, to quantify the perceived design difficulty, a new metric based on the degree of relationship between the system requirements and elements is proposed. This metric utilizes the domain mapping matrix and matrix energy to quantify the complexity of system design. Using the proposed metric, the relationship between system design complexity and design difficulty perceived by engineering experts is established and demonstrated through a case study involving a column-type electric power steering system.