Homogeneous state-space representation of concurrent design

Abstract

In engineering design, it is not uncommon for design tasks to iterate several times before the entire design process is completed; the greater the number of iteration, the longer the product development time and cost. This paper discusses how the state-space representation of concurrent, coupled design tasks may be employed to model, monitor and control the entire design process. A case study of a camera design, consisting of four coupled tasks and modelled by the state-space concept and by the work transformation matrix (WTM), is discussed. The state-space solutions were found to be very close to the WTM solutions. The computed eigenvectors were identical with each other. The eigenvectors of the state-space representation can be used as in the WTM to identify the 'controlling features', those elements of a coupled design problem that required the greatest number of iterations to reach a technical solution. The state-space concept can potentially minimize the duration of the entire design process even before the first design task begins. If it is applied early in design planning, tasks that require many iterations to complete can be identified and rectified. The state-space analysis also reveals the natural stability behaviour of the design iteration process for stability assessment, notably the response shape and rate of convergence of the tasks.