Robust parallel design of the subsystems constituting a complex system

The problem of designing complex systems, with performance specifications from multiple disciplines, consisting of several subsystems, and where the subsystems are designed in parallel is addressed. The subsystems interact in the sense that the performance of one subsystem is influenced by the design details of other subsystems. This introduces uncertainty into the design process. A team designing a given subsystem needs design details from other subsystems to evaluate its subsystem performance. If the subsystems are designed in parallel, these design details are generally not readily available. In this paper, we formulate the subsystem design problems using a robust design framework. Nonlinear optimization is used to design subsystems that are robust with respect to the uncertainties arising from designing the subsystems in parallel. In addition to its own uncertain design parameters, the uncertain parameters for a given subsystem include the design variables and outputs from other subsystems that are needed in that subsystem analysis. Accounting for these uncertainties allows the subsystems to be designed in parallel while guaranteeing achievement of system-level performance specifications upon assembly of the subsystems. The proposed robust parallel design (RPD) approach is illustrated using a passive suspension design example for a half-car model.