Optimal design processes under uncertainty and reciprocal dependency

Abstract

Design processes are characterised by uncertainty and iteration, making them difficult to plan and manage. These characteristics are incorporated into an original model in which information flow is simulated explicitly such that the dynamic complexity of design processes with interdependent tasks is captured. This is accomplished through the linkage of information exchange to the work done during each design task, the availability of resources, and the techniques used to manage the product development (PD) process. The model generates rework due to iteration and failure in design reviews according to the ability of tasks to reduce the uncertainty of design information. The model is applied to the investigation of coordination and its effects on process behaviour under various conditions. Coordination mechanisms are studied through the choice of input parameters that influence the degree of overlapping of tasks, the allocation of resources that process information, the delay of communication of information, and the interval of communication between tasks. Findings uncover the mechanisms that drive the pace of progress during engineering design processes and highlight strategies that reduce span time in complex PD.

Keywords:

• dependency modelling
• complex system
• design
• simulation
• coordination

Notes

Process maturity is defined in the CMMI (capability maturity model integration) by the Software Engineering Institute of Carnegie Mellon University, http://www.sei.cmu.edu/cmmi/research/.

The inverse PDF, also known as the inverse probability integral transform or inverse transformation method, is a basic method for generating numbers at random from any probability distribution (Devroye 1986).

Recall from Section 2.2 that design iteration implies rework or refinement of activities to account for changes in their inputs.