Tradespace Analysis Research Articles

Progress toward a DoD Ground Vehicle Tradespace and Affordability Analysis Framework

During ground system conceptual design and engineering development many tradeoff decisions are made to balance functional performance, cost, risk, robustness, reliability, interoperability, growth margin, and other life-cycle characteristics. Tradespace analysis reveals and quantifies the compound and ripple effects and interactions among performance requirements and system design options. An analytic tradespace framework is an executable model that represents the logical and causal relationships among vehicle subsystems and system performance characteristics. Logical relationships define compatibility requirements between interacting subsystems. Causal relationships quantify higher level system attributes as functions of lower level subsystem attributes. Research at the US Army, TARDEC, has been developing a generic ground system performance specification framework, and a ground system standard product classification hierarchy. The current research seeks to integrate these two frameworks with a unifying framework of the logical and causal relationships. The tradespace framework identifies the relevant subsystem attributes and how they interact to govern product performance and life-cycle characteristics, and identifies the subsystem interfaces and compatibility characteristics that constrain and enable practical ground vehicles. The objective is a qualitative and quantitative framework integrating system architecture and technology options with functional and life cycle performance to support design and performance requirement decisions. The goal is to integrate the ground system architecture and performance specification frameworks for interactive tradespace analysis and exploration. The research is motivated by, and grounded in, an understanding of the performance and affordability tradespace decisions and supporting analysis in ground vehicle development programs.

Georgia Aquarium Design Space Analysis and Optimization

The Ocean Voyager exhibit residing at the Georgia Aquarium Inc. (GAI) is one of the largest reef gallon aquariums in the world, with a capacity greater than 6.2M gallons. Reef aquariums are closed systems and must compensate by ‘turning over’ their complete volume of water many times a day through biological, chemical, and mechanical filtration. Due to the Georgia Aquarium being a non-profit organization, GAI sought to investigate ways to maximize efficiency and lower operating costs. This paper will focus on using low-cost software solutions to perform trade space analyses and optimization directed towards the Ocean Voyager exhibit and related GA Aquarium life support and energy systems.The software solution herein demonstrates a top-down System of Systems (SoS) to subsystem modeling approach that provides decision makers with interdisciplinary dashboard-level tools to visualize system design. The goal of the analysis is to provide executive level decision-making support for designing or enhancing existing complex systems and SoS. The analysis was performed as a capstone project by Georgia Tech graduate students progressing from cradle to finish in just 9 weeks to show the benefits of systems engineering to Georgia Aquarium staff. Integrating software SE tools into a single, aggregate model enables project engineers and decision makers to direct design directions with confidence.

4.3.3 Integrated Toolset and Workflow for Tradespace Analytics in Systems Engineering

Complex system development, especially in the context of large-scale military acquisition programs, requires integrated systems engineering tools to enable effective exploration of the design alternative tradespace. The prototype development described herein offers a capability framework through which tradespace analyses of materiel solutions may be extended and new analytical methods or formalisms may be matured. This effort leveraged expertise and lessons learned from previous, customer-specific toolsets to design a flexible, open, and integrated architecture supported by a structured but also flexible workflow. The result is a design space environment built on open source technologies where new analytical methods may be explored, refined, and linked together while conducting rational comparison of design alternatives. This effort also builds upon prior research to operationalize analytical dimensions that will enable designers to evaluate the resiliency of designs across competing stakeholder needs and/ or changing performance requirements.

Range Improvements in Gliding Reentry Vehicles from Thrust Capability

There are diverse applications in which control of a gliding hypersonic reentry vehicle is needed. Recently, it has become feasible to predict the maximum reachable footprint a vehicle can achieve given a span of boundary conditions and constraints. This capability is being newly incorporated into the vehicle design process. The present work demonstrates a method to quickly approximate a footprint area and how such predictions can be informative to design considerations and trajectory planning. The novel design feature investigated is the presence, or absence, of an engine thrusting axially along the vehicle body. Three pairs of notional vehicles, one designed with an engine and one without, are motivated. Reachable footprint dimensions are presented for each and compared over the constraint space and engine design. It is shown that the performance increase, due to the presence of an engine, is most dramatically seen in a situation where a reentry vehicle must divert from a preplanned trajectory. In such a scenario, as time to target decreases, the ratio of reachable footprint area of a vehicle with an engine to that without significantly increases. This insight demonstrates new trade space analysis to inform vehicle design.

Trade Space, Product Optimization, and Parametric Analysis

This article shows how to bound, build, and assemble trade spaces for product optimization. The advent of computerized tools that describe available trade spaces has changed not only the nature of optimized product design, but that of parametric cost studies as well. Because these tools allow broader analysis, engineers can produce many more potential designs. Those tools, explained in this article, allow parametricians to analyze trade spaces in a manner that allows them to determine the sets of product attributes that have the best chance for market success. However, rather than trailing such engineering studies, parametricians may be able to lead them. In the process, parametricians may be able to move their organizations toward more economically viable configurations, those that markets will more readily accept.

Resilience-based System Importance Measures for System-of-Systems

Systems-of-systems (SoS) like the air transportation system and missile defense are gaining increasing attention in both the academic and practitioner communities. This research investigates one crucial aspect of SoSs: their ability to recover from disruptions, or their resilience. We develop a family of system importance measures (SIMs) that rank the constituent systems based on their impact on the overall SoS performance. The SIMs address some of the major weaknesses that have prevented researchers from identifying a single resilience metric. While trade-space analyses are standard practice in systems engineering, conducting trades on SoS resilience is difficult because, to date, no reliable and consistent metrics have been developed for SoS resilience. Some metrics have been proposed, but these measures assume homogenous networks, thus ignoring one of the key features of SoSs: the combination of heterogeneous systems (e.g., airports and aircraft) to achieve a common goal (e.g., transport). Instead of focusing on an overall metric, the set of SIMs provides designers with specific information on where an SoS is lacking resilience (or has excess resilience) and hence on where improvements are needed (or where downgrades are possible).

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.

Interdependent Multi-Layer Networks: Modeling and Survivability Analysis with Applications to Space-Based Networks

This article develops a novel approach and algorithmic tools for the modeling and survivability analysis of networks with heterogeneous nodes, and examines their application to space-based networks. Space-based networks (SBNs) allow the sharing of spacecraft on-orbit resources, such as data storage, processing, and downlink. Each spacecraft in the network can have different subsystem composition and functionality, thus resulting in node heterogeneity. Most traditional survivability analyses of networks assume node homogeneity and as a result, are not suited for the analysis of SBNs. This work proposes that heterogeneous networks can be modeled as interdependent multi-layer networks, which enables their survivability analysis. The multi-layer aspect captures the breakdown of the network according to common functionalities across the different nodes, and it allows the emergence of homogeneous sub-networks, while the interdependency aspect constrains the network to capture the physical characteristics of each node. Definitions of primitives of failure propagation are devised. Formal characterization of interdependent multi-layer networks, as well as algorithmic tools for the analysis of failure propagation across the network are developed and illustrated with space applications. The SBN applications considered consist of several networked spacecraft that can tap into each other's Command and Data Handling subsystem, in case of failure of its own, including the Telemetry, Tracking and Command, the Control Processor, and the Data Handling sub-subsystems. Various design insights are derived and discussed, and the capability to perform trade-space analysis with the proposed approach for various network characteristics is indicated. The select results here shown quantify the incremental survivability gains (with respect to a particular class of threats) of the SBN over the traditional monolith spacecraft. Failure of the connectivity between nodes is also examined, and the results highlight the importance of the reliability of the wireless links between spacecraft (nodes) to enable any survivability improvements for space-based networks.

Model-Based Systems Engineering Design and Trade-Off Analysis with RDF Graphs

Within the Semantic Web community, resource description frameworks (RDF) and logical reasoning engines work together to provide semantic support and reasoning for Web applications. This paper explores the use of RDF graphs for the representation of graphs of requirements and specification of design component properties. We show that the component selection design problem and associated trade-space analysis can be cast as a sequence inference analyses on RDF graphs. Inference procedures are provided for assessment of requirements in terms of component attribute values, identification of compatible component interface pairs, component selection to meet the system architecture requirements, and computation of system cost, performance and reliability. Our prototype implementation makes extensive use of Java and Python, and focuses on the satisfaction of requirements and component selection for a home theater design problem.

Theory and tradespace analysis of a reflective axial adaptive optical zoom system

Optical zoom enables wide and narrow fields-of-view within a single optical system. Traditional zoom designs translate elements along the optical axis, a technique that is generally prohibitive for large diameter optics. Adaptive optical zoom (AOZ) alters system magnification via variable focal length elements, a technique that has the potential to facilitate zoom in large diameter systems. This paper details a novel optical theory developed to design AOZ systems. The developed theory modifies existing techniques for telescope objective design and third-order aberration determination to accommodate the additional degrees of freedom found with AOZ. The derived theory also enables a large-scale tradespace analysis, allowing optical design to begin from a broad perspective and optimize a particular design. Using the tradespace analysis, a Cassegrain AOZ objective with a 3.3Xzoom ratio is designed, demonstrating the capability and validity of the theory.

Integrated modeling for design of lightweight, active mirrors

Lightweight, active, silicon carbide mirrors have the potential to enable larger primary aperture, space-based optical systems, hence improving the resolution and sensitivity of such systems. However, due to the lack of design heritage, the best mirror designs are not yet known. Therefore, an integrated model of the lightweight mirrors is created in order to explore the design space. The model determines the achievable radius of curvature change within wavefront error limits, the peak launch stress, and the mass of a mirror segment. However, designing a mirror to meet any of these individual objectives results in a system that performs poorly in terms of the other objectives. Therefore, a full trade space analysis is run to determine the portions of the design space that best balance the trade-offs between metrics. These results are used to determine designs that perform well with respect to specific missions and can be used for future mirror designs.

Intelligent Tools Used in the Design of Navy Ships

AbstractThe first step in implementing an intelligent ship is designing the ship intelligently. Naval ship design is becoming an interactive process where designers on different sites can work collaboratively and simultaneously, connected through virtual design environments. In this paper we introduce two such design environments. The first is an immersive, virtual reality environment enabling rapid design of ship space arrangements, exploration of Human System Integration issues, and reduced cost of test and evaluation through the use of modeling and simulation. The second is a systems engineering application capable of evaluating the benefit of spiral technology insertions, identifying areas for research and development investment, and evaluating the performance, risk, and affordability of proposed technologies in current and future ship systems, by conducting trade space analysis and optimization. Applications of these tools will be discussed.