Christina L. Bloebaum

The Distinct and Interrelated Roles of Value-Driven Design, Multidisciplinary Design Optimization, and Decision Analysis

The different intents and capabilities of Value-Dri ven Design and Multidisciplinary Design Optimization are explored, compared, and contrasted. A distinct and necessary role is found for each technique. The foundation of both research areas in Decision Analysis is explored, particularly in the context of Multidisci plinary Design Optimization and ValueDriven Design for Large-Scale Complex Engineered Systems.

Design of Complex Engineered Systems

Many past editorials have discussed definitions of design, ointing out the wide variation across individuals and industries. e adhere to a definition that recognizes design to be a matter of aking rational decisions regarding available alternatives in order o achieve one’s stated preference. In an upcoming special issue of his journal, research articles on the topic of “designing complex ngineered systems” are being invited. This begs the question: hat is a complex engineered system? Further, what are the nique design challenges of such systems? We define complex systems to be those for which tightly oupled interacting phenomena yield a collective behavior that annot be derived by the simple summation of the behavior of the arts. In essence, these are highly interdisciplinary systems in hich the existence of inherent couplings potentially leads to irational results. Complex systems may be biological human ody , natural rain forests , or engineered aerospace, naval arhitectures, drilling platforms, and medical devices . Growing human needs in national defense, environmental susainability, medical advancements, and human prosperity, in genral, have been drivers in the increased complexity seen in engieered systems. However, whether one is designing a new aterial for a particular behavior across scales or a large-scale ransportation system, involving numerous interacting disciplines, he inherent couplings wreak havoc with the practice of imposing traditional structured hierarchical design process. Further, there s little room today for an antiquated organizational approach ooted in single discipline superiority. In general, present efforts to address complexity in engineering esign tend toward managing the complexity through more proesses rather than attempting to rigorously understand it through heory or even exploit it to improve system performance. While he reliance on traditional methodologies and processes tied to a articular organizational structure can have detrimental results at he smaller scale, the failures are magnified substantially for largecale complex products. Today, the most common system engieering approaches involve using a hierarchical decomposition ithin a requirements-driven framework. Even the most meticuous implementation of this approach when used for large-scale omplex systems such as military aircraft can still lead to mindoggling cost overruns in the hundreds of millions of dollars and ubstantial time delays that set projects back by years or even ead to project cancellation . We can and we must reverse this attern. The widespread and rapidly growing prevalence of comlex engineered systems means that the critical gaps in design heory and methodology have pervasive and damaging impacts rom small to large scales. Now, more than ever, our engineering design community must ise to the challenge of addressing these issues. However, what

A Research Agenda for Tradespace Exploration and Analysis of Engineered Resilient Systems

This paper describes the activity of a workshop on Data-Driven Tradespace Exploration and Analysis: A Key Technical Thrust of Engineered Resilient Systems (ERS). The workshop was attended by 40 academic, government, and industry researchers and practitioners involved in tradespace exploration for a variety of engineering domains. The one-and-one-half day workshop sought to develop near and far term tradespace technology research recommendations for the ERS Priority Steering Council (PSC) Lead. To determine promising research areas, workshop attendees were asked to describe desired tradespace capabilities, the associated current approach and its deficiencies, and gaps between the two states. These research areas were summarized in statements of need, supporting rationale, and investment timeframe. Resilience in the context of ERS is more than robustness; resilience implies that when the system is placed into an environment in which it was not originally intended to operate, after some degradation in performance, the system can be adapted or reconfigured to perform at its intended levels. To support design for resilience, more alternatives must be generated earlier, considered longer, explored over multiple, dynamic alternative futures, and searched exhaustively. The workshop described in this paper was organized to discuss current methods, process, and tools for performing these tradespace analysis related tasks and to better understand existing tradespace capabilities and their suitability for ERS.

Toward a Value-Driven Design Approach for Complex Engineered Systems Using Trade Space Exploration Tools

Design decision-making involves trade-offs between many design variables and attributes, which can be difficult to model and capture in complex engineered systems. To choose the best design, the decision-maker is often required to analyze many different combinations of these variables and attributes and process the information internally. Trade Space Exploration (TSE) tools, including interactive and multi-dimensional data visualization, can be used to aid in this process and provide designers with a means to make better decisions, particularly during the design of complex engineered systems. In this paper, we investigate the use of TSE tools to support decision-makers using a Value-Driven Design (VDD) approach for complex engineered systems. A VDD approach necessitates a rethinking of trade space exploration. In this paper, we investigate the different uses of trade space exploration in a VDD context. We map a traditional TSE process into a value-based trade environment to provide greater decision support to a design team during complex systems design. The research leverages existing TSE paradigms and multi-dimensional data visualization tools to identify optimal designs using a value function for a system. The feasibility of using these TSE tools to help formulate value functions is also explored. A satellite design example is used to demonstrate the differences between a VDD approach to design complex engineered systems and a multi-objective approach to capture the Pareto frontier. Ongoing and future work is also discussed.Copyright

Profit and Operational-Based Value Functions

Design and development of large scale complex engineered systems require engagement and coordination of thousands of individuals spanning multiple companies and organizations, making decisions driven largely by prescribed requirements. One issue in this development process is related to the stakeholder desires and the ability to effectively communicate stakeholder preferences to the designers, who are often distributed across teams, organizations, and countries. Value-Driven Design is an approach from systems engineering that attempts to address this issue. Another issue is that stakeholders from military organizations typically have very different preferences from profit driven organizations. Multiple types of value functions are explored in this paper to contrast these two perspectives. Value functions are formed to understand their impacts on the high level design of a strategic strike aircraft. Both monetary and operational value functions are used to understand how preferences on the system influence the final design. More specifically, profit seeking value functions are contrasted with operational value functions to demonstrate the different decisions that would result from each, thereby leading to vastly different system designs.

Increased System Consistency through Incorporation of Coupling in Value‐Based Systems Engineering

The design of large-scale complex engineered systems involves hundreds to thousands of designers making decisions across different organizations and at different levels of organizational hierarchy. These systems are designed within a systems engineering framework, where requirements are used as proxies for stakeholder preference. Requirements drive the development process and are flowed across organizations and down through the organizational hierarchies. Value-driven design offers a new perspective where the preferences of the stakeholder are communicated directly through a decomposable value function, rather than decomposable requirements, thereby enabling improved consistency in system preference. This paper investigates two key aspects of achieving improved system consistency through a value-based systems engineering approach, using a commercial satellite system as a testbed. The paper first contrasts the diverse systems that result from traditional requirements-based versus preference-based formulations, demonstrating how a value-based approach aids in capturing the true preferences of the stakeholder in problem formulation. The paper demonstrates the importance of using system couplings to enable an improved accuracy for value function decomposition. The paper demonstrates that ensuring system analysis consistency through use of system sensitivities can overcome issues pertaining to: dependencies of attributes; inadequately capturing system interactions; and direct modification of attributes to determine value impact.

Adding Value to Trade Space Exploration When Designing Complex Engineered Systems

Design decision-making involves tradeoffs between many design variables and attributes, which can be difficult to model and capture in complex engineered systems. To choose the best design, the decision maker is often required to analyze many different combinations of these variables and attributes and process the information internally. Trade Space Exploration (TSE) tools, including interactive and multidimensional data visualization, can be used to aid in this process and provide designers with a means to make better decisions, particularly during the design of complex engineered systems that have multiple, competing objectives. In this paper, we investigate the use of TSE tools to support decision makers using a Value-Driven Design (VDD) approach for complex engineered systems. A VDD approach necessitates a rethinking of TSE, and we outline and illustrate four different uses of a VDD approach to TSE. The research leverages existing TSE paradigms and multidimensional data visualization tools to identify optimal designs when using a value function for a system. A satellite design example is used to demonstrate the differences between a VDD approach to design complex engineered systems and a multiobjective approach to capture the Pareto frontier. Ongoing and future work is also discussed.

Value Impact of an Organization Structure in the Context of Value-Driven Design

The design of Large-Scale Complex Engineered Systems (LSCESs) involves large organizations and groups of individuals. The structure of an organization impacts the design process and is therefore an essential component to the design and development of complex engineered systems. Previous work has demonstrated the merits of using Value-Driven Design (VDD) to improve the engineering process to capture true stakeholder preference, particularly when using Multidisciplinary Design Optimization (MDO) frameworks to design these complex systems. Organization Design (OD) has contributed significantly to the understanding of organization structures and their relationships to efficient resource use. The focal point of this paper is the incorporation of organization structures to the value driven approach of designing complex systems. In particular, the impacts of organization structure on the design process and the design product is explored. A commercial communication satellite is used as an example LSCES to show how capturing the impact of change in organization structure (through individual and team interfaces) can affect the value of a system and thereby provide a means for more informed decision making. The satellite system’s design is considered in both certain and uncertain conditions. The value function used incorporates attributes characterizing the system as well as the engineering process (such as time and analysis costs). The paper demonstrates that the organization structure does affect the value of the system and should be considered at the beginning of the design process.

Preference Modeling for Government-Owned Large-Scale Complex Engineered Systems: A Satellite Case Study

The design of large-scale complex engineered systems (LSCES) has been shown to be a distributed decision-making problem involving hundreds or thousands of designers making decisions at different levels of an organizational hierarchy. Traditional systems engineering (SE) approaches use requirements to communicate the preference(s) of stakeholders to drive the decisions of the designers. Requirements, which act as proxies for actual preferences, only state what is not desired of the system rather than what is wanted. This leads to a lack of consistency in the communication of preferences across the subsystems (and even organizations) involved. Also, the current requirements-based SE approaches do not offer any system-level guidance in choosing the best among feasible design alternatives, where all the designs that satisfy requirements are treated equally. Value-driven design (VDD), an alternative SE approach, offers a new perspective on complex system design and emphasizes the importance of capturing true preferences of stakeholders using a meaningful decomposable value function. The formulation of an all-encompassing value function has been proven to be a very tedious process involving a huge overhead, as it requires understanding of the inherent design trades in the system. Past researchers have focused in detail on formulating value functions for commercial endeavors. The primary focus of this paper is to investigate how the formulation of value functions can be approached in a methodical manner using a data-based approach, specifically for a government-based agency (e.g., NASA). More specifically, this paper focuses on formulating a value function for a space telescope mission by identifying and analyzing different aspects involved in capturing preferences.

A Value-Driven Approach to Capture Unintended Consequences Impacting Mission Success

Large-scale complex engineered systems are systems whose complexity and numerous inherent couplings can lead to unintended consequences or unanticipated behaviors during system operation. In many cases, these behaviors have negligible impact on system functionality; however, some unanticipated behaviors can contribute to a deficiency or even a failure of the system. Capturing these behaviors during the design and development phase (before testing and operation) can aid system managers in a reduction of time, costs, or even cancellation of projects due to a disastrous unforeseen interaction. Early identification also aids engineers to redesign components at an early phase of the development process, instead of relying on mitigation to address the issue after the fact. The goal of this paper is to use a coupling strength analysis from the field of multidisciplinary design optimization (MDO) to identify possible unanticipated behaviors or consequences due to interactions that were previously assumed of little importance. An evaluation of possible losses in value due to unforeseen behaviors will also be made using a value-based systems engineering (VBSE) approach.