11.4.3 The Tradespace Exploration Paradigm

Abstract

Abstract. Over the past five years, researchers working on a number of system design projects in the Space Systems, Policy, and Architecture Research Consortium (SSPARC) at the Massachusetts Institute of Technology (MIT) have developed a process of value-focused, broad tradespace exploration for the development of space systems. The broad tradespace framework has provided insights into communicating and quantifying the impact of changing requirements, uncertainty, and system properties such as flexibility and robustness. Additionally, insights have been made in applications to more complex cases, such as analyzing policy effects on system cost and performance, as well as understanding the time-dependent effects of architecture and design choices for spiral development. The tradespace exploration paradigm both broadens the perspective of designers in conceptual design to better understand the "physics" of the proposed solutions relative to one another, and focuses the designer on delivering systems of value to key system stakeholders.

Margins Leading to Over-Capacity

“…In the context of mechanical engineering, design margins are added to provide flexibility; flexibility itself being defined as providing "functionality, performance, and capacity" each of which "consists of many attributes, which can also be thought of as requirements" (Banerjee and de Weck, 2004). The flexibility of a product can be assessed by systematically anticipating and rating the potential future changes to "future proof" the design, which will inevitably introduce a degree of overdesign into the product (Ross and Hastings, 2005). De Neufville et al (2006) advocates "design options" as a form of deliberate planning for anticipated changes, which is costed and deliberately decided upon.…”

“…From an energy efficiency perspective, an over-engineered building services system is likely to be too large to operate at its optimum efficiency point (Djunaedy et al 2011, Bacon, 2014. A Building Services Research and Information Association (BSRIA) guide to building services calculations states that "margins should never be added during a calculation process without an adequate reason for doing so and with the approval of a senior engineer" furthermore "if any margins are used they should be clearly identified and a justification given for their use" (BSRIA, 2007). Despite BSRIA producing guidance on the use of engineering design margins for building services through the promotion of better design consistency and standards (Race, 2007), it is evident from the hospital boiler case study and the authors professional practise working within the building services industry, that this guidance is largely being ignored and that the practise of applying excessive margins continues to be accepted.…”

Defining changeability: Reconciling flexibility, adaptability, scalability, modifiability, and robustness for maintaining system lifecycle value

“…A reasonable approach to comparing a large number of systems simultaneously is through a tradespace [Ross and Hastings, 2005]. Figure 7 below depicts the elements that go into tradespace development.…”

A Method for Exploring Program and Portfolio Affordability Tradeoffs Under Uncertainty Using Epoch-Era Analysis: A Case Application to Carrier Strike Group Design

“…TSE empowers system engineers to consider far more potential designs than could be done through prior Analysis of Alternatives methods (Ross & Hastings, 2005). A recently developed approach, ^Åèìáëáíáçå=oÉëÉ~êÅÜ=mêçÖê~ãW= êÉ~íáåÖ=póåÉêÖó=Ñçê=fåÑçêãÉÇ=`Ü~åÖÉ= -202 -Epoch-Era Analysis (EEA), enables the conceptual design of systems that are resilient to potential changes in context and needs (exogenous uncertainties) over the lifecycle of the system.…”