Michael Pennotti

SUPPORTING THE SYSTEM ARCHITECT: MODEL-ASSISTED COMMUNICATION

System modeling and analysis is used to validate assumptions, increase understanding, synchronize views, and support decisions. By measuring indirect related quantities and commonalities of different modeling techniques in practice we can get an indication of the value of modeling. In this paper, we discuss how to increase modeling value and provide more effective model-assisted communication by understanding critical success factors of modeling. We analyze models used to support production line design at Volvo Aero Norge AS. Volvo Aero Norge AS manufactures jet engine components for commercial and military engine suppliers. Flight safety is fundamental in the domain which translates to comprehensive component quality and traceability requirements. Long-term engine programs make production line development and process improvements important for staying competitive and maintaining a profitable production that supports the required quality level. System modeling and analysis is applied to communicate insight between stakeholders and visualize different aspects of production lines and processes. In this paper we present impact factors the architect can use to increase a models ability to assist communication. We argue how balancing and utilizing the right quantity of these factors increase modeling value.

Evaluating the effectiveness of systems and software engineering methods, processes and tools for use in defense programs

The Systems Engineering Research Center University Affiliated Research Center (SERC-UARC) at Stevens Institute has been tasked to evaluate the effectiveness of the systems and software engineering processes, methods and tools (MPTs) used in US Department of Defense acquisition and development programs. This paper presents the selection and evaluation process, describes its evolution based on changing sponsor needs, and presents additional information on the characterization of MPTs for evaluation.

Requirement Elicitation and Validation by Prototyping and Demonstrators User Interface Development in the Oil- and Gas Industry

Incomplete or misinterpreted requirements are a significant source of customer and user dissatisfaction in development of software user interfaces. In these systems, where consideration of the human factor is a vital part of the development, the undertaking of understanding the real needs of the user must not be underestimated. Unfortunately, there are often organizational boundaries which restrict or limit the developers opportunities to communicate with the customer and stakeholders. The result is often a weak link between the stakeholder needs, system requirements and the realization of the user interface system. This paper addresses how an approach to requirements engineering based on a combination of rapid prototyping and demonstrator sessions can be used to elicit requirements and obtain early feedback and acceptance from system stakeholders. The method was conducted on a user interface development project for gas turbine driven generator and compressor packages in operation at offshore oil-rigs. Stakeholders were presented with module prototypes with a varying degree of dynamics, simulation and interaction based on the stage of the development. Together with rationale-based questioning, the demonstrator sessions provided a context for constructive discussions and feedback. The developers returned with a better understanding of the rationale for stakeholder need and clarification of misinterpreted or poorly defined requirements. This enabled us to create an application better aligned with customer and user needs and a minimal amount of rework and updates after system deployment.

Exploring Risk Management for a Space Simulator

Space simulators are vital to prepare astronauts for future missions in Earth orbits, and later to the Moon and beyond. The National Aeronautics and Space Administration’s (NASA) legacy space simulators have been mostly static or limited dynamic trainers that lower the risk for humans going to space. A group of graduate students from Stevens Institute of Technology applied systems engineering to develop a concept for a motion-based centrifuge space simulator. Such a simulator entails many risks, and many controls are available to mitigate these risks. This paper assesses a modified method of identifying and mitigating the risks of using a space simulator.

High Profile Systems Illustrating Contradistinctive Aspects of Systems Engineering

Abstract Many modern systems have a high degree of dependence on embedded software in order to perform their required functions. Some examples include transportation systems, hand-held devices, and medical equipment, among others. In designing their products, systems engineers typically take a top-down, process-oriented approach, decomposing a complex system into simpler, easier to manage, subsystems; the system requirements can then be allocated and flowed down as necessary to the appropriate subsystems. Software engineers take a more bottom-up, object-oriented approach, using simple building blocks to create a more complex system, and enhancing their existing blocks with new ones where necessary. In many cases, both techniques must be employed together in order to design a successful system. Although it may have been acceptable in the past for simpler systems to view software as a separate subsystem with a fixed set of requirements, greater complexity of modern systems requires a corresponding improvement in working methodology. With the software playing an increasingly pivotal role, systems engineers must become much more familiar with the architecture of the software than previously; Likewise, software engineers need a systems-level view to understand which aspects of the design could be volatile due to new stakeholders (bringing with them new requirements), technology upgrades, and the changing world in general. Systems whose success or failure play out in the public arena provide a rare opportunity to study the factors that contribute to their outcome. Using two such systems, the Denver International Airport baggage handling system and the Apple iPad, this paper will study some best practices that can lead to project success or failure, and show the importance of a rigorous capture and flow down to both hardware and software of the requirements that must be correct from the start, as well as of designing an architecture that can accommodate the inevitable changes to a system. Designing extensible systems with a tolerance for future changes is a key factor in modern complex systems. The baggage handling system failed in part because of a failure to appreciate the central role of software and an apparent lack of a suitable strategy for handling requirement changes. Methods for creating software which is resilient to change have been well studied; however what may be somewhat lacking even to the present day is a broader education of the existing body of knowledge, and how to integrate it with systems engineering methods. The iPad succeeded where many of its predecessors had failed by a successful application of traditional systems engineering techniques and correctly implementing the hardware elements. Coming from companies with experience in software development, the system extensibility was not an issue in this case. However, the designers of the earlier systems seemingly failed to understand the actual market needs, failed to develop a corresponding set of requirements to meet those needs, and failed to translate those requirements into an integrated hardware/software solution.

The evolution of software and its impact on complex system design in robotic spacecraft embedded systems

Abstract The growth in computer hardware performance, coupled with reduced energy requirements, has led to a rapid expansion of the resources available to software systems, driving them towards greater logical abstraction, flexibility, and complexity. This shift in focus from compacting functionality into a limited field towards developing layered, multi-state architectures in a grand field has both driven and been driven by the history of embedded processor design in the robotic spacecraft industry.The combinatorial growth of interprocess conditions is accompanied by benefits (concurrent development, situational autonomy, and evolution of goals) and drawbacks (late integration, non-deterministic interactions, and multifaceted anomalies) in achieving mission success, as illustrated by the case of the Mars Reconnaissance Orbiter. Approaches to optimizing the benefits while mitigating the drawbacks have taken the shape of the formalization of requirements, modular design practices, extensive system simulation, and spacecraft data trend analysis. The growth of hardware capability and software complexity can be expected to continue, with future directions including stackable commodity subsystems, computer-generated algorithms, runtime reconfigurable processors, and greater autonomy.

Developing and validating a framework for integrating systems and software engineering

As illustrated in the harmonization of ISO 15288 and ISO 12207, the disciplines of systems engineering and software engineering share many processes, methods, and concerns. In most systems of interest, software now provides a significant majority of functionality and increasingly is a significant component in determining non-functional attributes. Failures in system acquisition and implementation are often attributed to systems and/or software engineering shortfalls. The need to apply systems engineering to software design and development, as well as the need to incorporate software engineering concepts into systems engineering decisions, implies that a closer relationship between the two disciplines is appropriate. This paper states a clear rationale for integrating the two disciplines, defines a framework that establishes a vocabulary for discussing integration, and presents initial findings in using that framework to describe systems and software integration in ongoing defence programs.

The Crew Mission Trainer - A Space Operations Training Solution

The Crew Mission Trainer (CMT) is a conceptual simulator that was designed by a team of graduate students from Stevens Institute of Technology. This paper presents the issue of the lack of vehicle awareness training within current space operations training technology. Combining centrifuge technology with three degree-of-freedom simulator technology, the CMT provides the dynamic vehicle responses that result from vehicle operation. The astronaut crew would use vehicle awareness training, gained through architecture such as the CMT, in order to become intimately acquainted with the dynamic responses of the vehicle. By understanding the vehicle reactions allows the astronaut to recognize potential failures within the vehicle systems, much like when a racecar driver discovers a flat tire through the vehicle vibrations. The training technology currently being used does not provide for this level of vehicle awareness. The technology currently used for astronaut training is currently not capable of simulating the complete dynamic vehicle environment that includes simulating the harsh gravitational forces and subtle vehicle responses. The CMT concept, however, is designed to simulate all the dynamic responses of the vehicle, from shock and vibrational effects, to the effects experienced during increased gravitational loading. Sharing this concept with members of the space operations community, the CMT was viewed as being a possible solution to a technological need that would advance space operations training in the twenty-first century by providing vehicle awareness training.

Space Systems Architecture for the Crew Mission Trainer

NASA needs to prepare astronauts for spaceflight training in nominal and emergency scenarios for missions in the post -Shuttle era. NASA will be retiring Space Shuttle training and operations in concert with the Shuttle retirement by 2010, and the next astronaut class will rehearse in new Constellation training facilities. The strategic plan to move from a winged, reusable space vehicle to an in -line rocket with a crew capsule at the nose has changed the crew flight environment considerably. Relatively benign flight regimes for the crew have now been replaced with scenarios having more extreme flight conditions. Ground launches will have considerable vibrations, shock and accele rations, and capsule reentry/landings could have sustained load conditions of at least 7 Gs. A review of current Constellation training and operations architecture has indicated a poten tial gap in coverage for a full-task trainer that simulates the most extreme conditions. In order to support future space vehicle training and operations, a concept was developed for a dynamic three degree of freedom, centrifuge-based crew flight trainer which simulates the full mission environment in all flight phases. For this study, a rigorous systems engineering approach was used to create a fully integrated set of concept of operations, requirements, and an architecture that meets the needs of NASA in the 21st Century. Systems engineering techniques were applied to the architecture, using various analysis methods such as stakeholder interviews, use case diagrams, requirements definition, alternate design trades, and functional flow diagrams. The result of this study was a novel trainer based on commercially available technology that has received attention from NASA mission training/operations engi neers as a viable option for anticipated NASA plans regarding Constellation training and operations architecture. This analysis brought into focus the need for a trainer wit hin the overall Constellation architecture that simulates anticipated extreme environments. These environments include sustained positive and negative g-forces, acoustic environment, and vibration with flight-like displays, controls, and crew interfaces t hat will enable the crew to be prepared for nearly all possible flight scenarios. It was found beneficial to have all types of NASA flight training consolidated into one facility by using the proposed trainer, thus saving training time and cost.