Constraint capture and maintenance in engineering design

The Designers' Workbench is a system, developed by the Advanced Knowledge Technologies (AKT) consortium to support designers in large organizations, such as Rolls-Royce, to ensure that the design is consistent with the specification for the particular design as well as with the company's design rule book(s). In the principal application discussed here, the evolving design is described against a jet engine ontology. Design rules are expressed as constraints over the domain ontology. Currently, to capture the constraint information, a domain expert (design engineer) has to work with a knowledge engineer to identify the constraints, and it is then the task of the knowledge engineer to encode these into the Workbench's knowledge base (KB). This is an error prone and time consuming task. It is highly desirable to relieve the knowledge engineer of this task, and so we have developed a system, ConEditor+ that enables domain experts themselves to capture and maintain these constraints. Further we hypothesize that in order to appropriately apply, maintain and reuse constraints, it is necessary to understand the underlying assumptions and context in which each constraint is applicable. We refer to them as “application conditions” and these form a part of the rationale associated with the constraint. We propose a methodology to capture the application conditions associated with a constraint and demonstrate that an explicit representation (machine interpretable format) of application conditions (rationales) together with the corresponding constraints and the domain ontology can be used by a machine to support maintenance of constraints. Support for the maintenance of constraints includes detecting inconsistencies, subsumption, redundancy, fusion between constraints and suggesting appropriate refinements. The proposed methodology provides immediate benefits to the designers and hence should encourage them to input the application conditions (rationales)

Galileo: A strongly typed, interactive conceptual language

ABSTRACT Galileo, a programming language for database applications, is presented. Galileo is a strongly typed, interactive programming language designed specifically to support Semantic Data Model features (classification, aggregation and specialization) as well as abstraction mechanisms of modern programming languages (types, abstract types and modularization). The main contributions of Galileo are: a) the proposal of a flexible type system to model database structure and semantic integrity constraints; b) the inclusion of type hierarchies to support the specialization abstraction mechanism of Semantic Data Models. c) the proposal of a modularization mechanism to structure data and operations into interrelated units; d) the integration of the abstraction mechanisms into an expression based language that allows an interactive use of the database without resorting to a new stand alone query language. Galileo will be used in the immediate future as a tool for database design and, in the long term, as a high level interface for DBMSs

Structural Models based on Minimal Surfaces and Geodesics

This article presents the results of research carried out with respect to the geometric, formal and structural adaptation of minimal surfaces. These surfaces were discretized into strips developable on geodesic curves, and then used for the construction of timber gridshells. For this project, both physical and virtual models derived from the same geometric models were used. The objective was to demonstrate the validity of the use of models and the transformation that modelling is undergoing due to the use of digital tools, both software and hardware. These include, on the one hand, drawing and analysis software and, on the other, digitally controlled fabrication tools. This research focuses specifically on the design and construction of the Scherk Pavilion, a space where the results of various experiments in which the common factor was the use of models was transferred to a real scale

REM: Automatic for the People

We present the result of a year-long effort to think, design, build, realize, and manage the robotic, autonomous REM observatory, placed since June 2003 on the cerro La Silla, ESO Chile. The various aspects of the management and control are here surveyed, with the nice ideas and the wrong dead ends we encountered under way. Now REM is offered to the international astronomical community, a real, schedulable telescope, automatic for the People

Human and Robotic Mission to Small Bodies: Mapping, Planning and Exploration

This study investigates the requirements, performs a gap analysis and makes a set of recommendations for mapping products and exploration tools required to support operations and scientific discovery for near- term and future NASA missions to small bodies. The mapping products and their requirements are based on the analysis of current mission scenarios (rendezvous, docking, and sample return) and recommendations made by the NEA Users Team (NUT) in the framework of human exploration. The mapping products that sat- isfy operational, scienti c, and public outreach goals include topography, images, albedo, gravity, mass, density, subsurface radar, mineralogical and thermal maps. The gap analysis points to a need for incremental generation of mapping products from low (flyby) to high-resolution data needed for anchoring and docking, real-time spatial data processing for hazard avoidance and astronaut or robot localization in low gravity, high dynamic environments, and motivates a standard for coordinate reference systems capable of describing irregular body shapes. Another aspect investigated in this study is the set of requirements and the gap analysis for exploration tools that support visualization and simulation of operational conditions including soil interactions, environment dynamics, and communications coverage. Building robust, usable data sets and visualisation/simulation tools is the best way for mission designers and simulators to make correct decisions for future missions. In the near term, it is the most useful way to begin building capabilities for small body exploration without needing to commit to specific mission architectures

MINIMIZING STAR TRACKER OCCULTATIONS FOR NASA’S LUNAR RECONNAISSANCE ORBITER IN SUN-SAFE MODE

Due to degradation of the NASA’s Lunar Reconnaissance Orbiter’s (LRO) Inertial Measurement Unit, the LRO relies solely on its star trackers to maintain gyroless attitude control. In the event of an anomaly, the LRO is placed in sun-safe mode in order to reestablish normal operation, which constrains its attitude. While in sun-safe mode, the LRO’s star trackers experience occultations from local orbiting bodies and cannot maintain an attitude solution during these periods. This poses the risk of total loss of the spacecraft due to tumbling or depleted power supply. This thesis provides mission operators with a software-based tool for determining alternate sun-safe attitudes that reduce the occultation time, minimizing operational risk. Ephemeris data from orbiting bodies and the LRO are utilized to investigate occultation occurrences. Periods of star tracker occultations for any given time frame are determined based on the LRO’s fixed attitude. The goal of this thesis is to iterate alternate attitudes to define the ideal attitude that minimizes occultation occurrences. Additionally, data analysis is conducted to determine the ideal attitude update frequency for sun-safe mode based on operational constraints. The design of this software-based tool yields appropriate results for acquiring an ideal attitude solution for minimizing star tracker occultations, giving mission operators the freedom to choose attitude constraints, simulation fidelity, and attitude update frequency.Lieutenant, United States NavyApproved for public release. Distribution is unlimited

A low cost Virtual Reality interface for CAD model manipulation and visualization

The human-computer interface technology provided in modern CAD systems makes the use of two dimensional (2D) computer interfaces, e.g. a keyboard and mouse, to generate and interact with CAD models. In addition, all CAD systems project complex 3D CAD models on a two dimensional computer screen, and the designer has to understand the spatial relationship of the different parts in the assembly by visualizing it in his/her mind. Because of the 2D nature of the keyboard and mouse, his/her interaction with complex 3D CAD models is restrictive and unintuitive. As compared to the traditional computer interface, VR provides a more interactive and intuitive interface for interacting with complex 3D CAD models; however, the high cost related to the VR equipment and the high level of technical skill required for implementing these technologies have restricted the widespread acceptance of such useful technologies. With the development of low-cost VR technologies in recent years, VR solutions have become more accessible. The objective of the research presented in this thesis is to implement the currently available low-cost VR technology for providing solution to the human-computer interaction problems present in today\u27s CAD applications. The thesis first reviews and analyzes some of the low-cost VR applications which are available in the market for interacting with CAD models. It then elucidates the development and implementation of a low-cost VR human-computer interface, the VR CAD Model Viewer, which is capable of importing and rendering stereo views of CAD models made in CAD systems like Pro/Engineer. The application developed also provides the user with the 3D 6-degree of freedom Data Glove device to interact with CAD models using his/her hands. A human subjects study is also performed which aims at recording the interface performance and user feedback about the use and intuitiveness of the interface. Studying this new type of learning experience and charting its strengths and limits is an important frontier for cognitive science research, scientific modeling, and constructive pedagogy

HybridMDSD: Multi-Domain Engineering with Model-Driven Software Development using Ontological Foundations

Software development is a complex task. Executable applications comprise a mutlitude of diverse components that are developed with various frameworks, libraries, or communication platforms. The technical complexity in development retains resources, hampers efficient problem solving, and thus increases the overall cost of software production. Another significant challenge in market-driven software engineering is the variety of customer needs. It necessitates a maximum of flexibility in software implementations to facilitate the deployment of different products that are based on one single core. To reduce technical complexity, the paradigm of Model-Driven Software Development (MDSD) facilitates the abstract specification of software based on modeling languages. Corresponding models are used to generate actual programming code without the need for creating manually written, error-prone assets. Modeling languages that are tailored towards a particular domain are called domain-specific languages (DSLs). Domain-specific modeling (DSM) approximates technical solutions with intentional problems and fosters the unfolding of specialized expertise. To cope with feature diversity in applications, the Software Product Line Engineering (SPLE) community provides means for the management of variability in software products, such as feature models and appropriate tools for mapping features to implementation assets. Model-driven development, domain-specific modeling, and the dedicated management of variability in SPLE are vital for the success of software enterprises. Yet, these paradigms exist in isolation and need to be integrated in order to exhaust the advantages of every single approach. In this thesis, we propose a way to do so. We introduce the paradigm of Multi-Domain Engineering (MDE) which means model-driven development with multiple domain-specific languages in variability-intensive scenarios. MDE strongly emphasize the advantages of MDSD with multiple DSLs as a neccessity for efficiency in software development and treats the paradigm of SPLE as indispensable means to achieve a maximum degree of reuse and flexibility. We present HybridMDSD as our solution approach to implement the MDE paradigm. The core idea of HybidMDSD is to capture the semantics of particular DSLs based on properly defined semantics for software models contained in a central upper ontology. Then, the resulting semantic foundation can be used to establish references between arbitrary domain-specific models (DSMs) and sophisticated instance level reasoning ensures integrity and allows to handle partiucular change adaptation scenarios. Moreover, we present an approach to automatically generate composition code that integrates generated assets from separate DSLs. All necessary development tasks are arranged in a comprehensive development process. Finally, we validate the introduced approach with a profound prototypical implementation and an industrial-scale case study.Softwareentwicklung ist komplex: ausführbare Anwendungen beinhalten und vereinen eine Vielzahl an Komponenten, die mit unterschiedlichen Frameworks, Bibliotheken oder Kommunikationsplattformen entwickelt werden. Die technische Komplexität in der Entwicklung bindet Ressourcen, verhindert effiziente Problemlösung und führt zu insgesamt hohen Kosten bei der Produktion von Software. Zusätzliche Herausforderungen entstehen durch die Vielfalt und Unterschiedlichkeit an Kundenwünschen, die der Entwicklung ein hohes Maß an Flexibilität in Software-Implementierungen abverlangen und die Auslieferung verschiedener Produkte auf Grundlage einer Basis-Implementierung nötig machen. Zur Reduktion der technischen Komplexität bietet sich das Paradigma der modellgetriebenen Softwareentwicklung (MDSD) an. Software-Spezifikationen in Form abstrakter Modelle werden hier verwendet um Programmcode zu generieren, was die fehleranfällige, manuelle Programmierung ähnlicher Komponenten überflüssig macht. Modellierungssprachen, die auf eine bestimmte Problemdomäne zugeschnitten sind, nennt man domänenspezifische Sprachen (DSLs). Domänenspezifische Modellierung (DSM) vereint technische Lösungen mit intentionalen Problemen und ermöglicht die Entfaltung spezialisierter Expertise. Um der Funktionsvielfalt in Software Herr zu werden, bietet der Forschungszweig der Softwareproduktlinienentwicklung (SPLE) verschiedene Mittel zur Verwaltung von Variabilität in Software-Produkten an. Hierzu zählen Feature-Modelle sowie passende Werkzeuge, um Features auf Implementierungsbestandteile abzubilden. Modellgetriebene Entwicklung, domänenspezifische Modellierung und eine spezielle Handhabung von Variabilität in Softwareproduktlinien sind von entscheidender Bedeutung für den Erfolg von Softwarefirmen. Zur Zeit bestehen diese Paradigmen losgelöst voneinander und müssen integriert werden, damit die Vorteile jedes einzelnen für die Gesamtheit der Softwareentwicklung entfaltet werden können. In dieser Arbeit wird ein Ansatz vorgestellt, der dies ermöglicht. Es wird das Multi-Domain Engineering Paradigma (MDE) eingeführt, welches die modellgetriebene Softwareentwicklung mit mehreren domänenspezifischen Sprachen in variabilitätszentrierten Szenarien beschreibt. MDE stellt die Vorteile modellgetriebener Entwicklung mit mehreren DSLs als eine Notwendigkeit für Effizienz in der Entwicklung heraus und betrachtet das SPLE-Paradigma als unabdingbares Mittel um ein Maximum an Wiederverwendbarkeit und Flexibilität zu erzielen. In der Arbeit wird ein Ansatz zur Implementierung des MDE-Paradigmas, mit dem Namen HybridMDSD, vorgestellt