Virtual Prototyping through Co-simulation of a Cartesian Plotter

This paper shows a model-based design trajectory for the development of real-time embedded control software using virtual prototyping. As a test case, a Cartesian plotter is designed. Functional correctness of the plotter software has been ensured by means of co-simulation using a virtual prototype before deploying it on target. Except for the interface implementation, the software that is used in the co-simulation is identical to the software that is compiled to run on the target computing platform. Virtual prototyping is especially important if the real target can damage itself if it is operated outside its safe operation zone or when prototypes are not yet available for testing. The co-simulation of the software against a virtual prototype resulted in a first-time-right deployment on the real target

Software process modelling as relationships between tasks

Systematic formulation of software process models is currently a challenging problem in software engineering. We present an approach to define models covering the phases of specification, design, implementation and testing of software systems in the component programming framework, taking into account non-functional aspects of software (efficiency, etc.), automatic reusability of implementations in systems and also prototyping techniques involving both specifications and implementations. Our proposal relies on the identification of a catalogue of tasks that appear during these phases which satisfy some relationships concerning their order of execution. A software process model can be defined as the addition of more relationships over these tasks using a simple, modular process language. We have developed also a formal definition of correctness of a software development with respect to a software process model, based on the formulation of models as graphs.Peer ReviewedPostprint (published version

Using AI/expert system technology to automate planning and replanning for the HST servicing missions

This paper describes a knowledge-based system that has been developed to automate planning and scheduling for the Hubble Space Telescope (HST) Servicing Missions. This new system is the Servicing Mission Planning and Replanning Tool (SM/PART). SM/PART has been delivered to the HST Flight Operations Team (FOT) at Goddard Space Flight Center (GSFC) where it is being used to build integrated time lines and command plans to control the activities of the HST, Shuttle, Crew and ground systems for the next HST Servicing Mission. SM/PART reuses and extends AI/expert system technology from Interactive Experimenter Planning System (IEPS) systems to build or rebuild time lines and command plans more rapidly than was possible for previous missions where they were built manually. This capability provides an important safety factor for the HST, Shuttle and Crew in case unexpected events occur during the mission

SAGA: A project to automate the management of software production systems

The Software Automation, Generation and Administration (SAGA) project is investigating the design and construction of practical software engineering environments for developing and maintaining aerospace systems and applications software. The research includes the practical organization of the software lifecycle, configuration management, software requirements specifications, executable specifications, design methodologies, programming, verification, validation and testing, version control, maintenance, the reuse of software, software libraries, documentation, and automated management

Can space station software be specified through Ada?

Programming of the space station is to be done in the Ada programming language. A breadboard of selected parts of the work package for Marshall Space Flight Center is to be built, and programming this small part will be a good testing ground for Ada. One coding of the upper levels of the design brings out several problems with top-down design when it is to be carried out strictly within the language. Ada is evaluated on the basis of this experience, and the points raised are compared with other experience as related in the literature. Rapid prototyping is another approach to the initial programming; several different types of prototypes are discussed, and compared with the art of specification. Some solutions are proposed and a number of recommendations presented

Using formal models to design user interfaces a case study

The use of formal models for user interface design can provide a number of benefits. It can help to ensure consistency across designs for multiple platforms, prove properties such as reachability and completeness and, perhaps most importantly, can help incorporate the user interface design process into a larger, formally-based, software development process. Often, descriptions of such models and examples are presented in isolation from real-world practice in order to focus on particular benefits, small focused examples or the general methodology. This paper presents a case study of developing the user interface to a new software application using a particular pair of formal models, presentation models and presentation interaction models. The aim of this study was to practically apply the use of formal models to the design process of a UI for a new software application. We wanted to determine how easy it would be to integrate such models into our usual development process and to find out what the benefits, and difficulties, of using such models were. We will show how we used the formal models within a user-centred design process, discuss what effect they had on this process and explain what benefits we perceived from their use

Proof Theory, Transformations, and Logic Programming for Debugging Security Protocols

We define a sequent calculus to formally specify, simulate, debug and verify security protocols. In our sequents we distinguish between the current knowledge of principals and the current global state of the session. Hereby, we can describe the operational semantics of principals and of an intruder in a simple and modular way. Furthermore, using proof theoretic tools like the analysis of permutability of rules, we are able to find efficient proof strategies that we prove complete for special classes of security protocols including Needham-Schroeder. Based on the results of this preliminary analysis, we have implemented a Prolog meta-interpreter which allows for rapid prototyping and for checking safety properties of security protocols, and we have applied it for finding error traces and proving correctness of practical examples