Simulation Environment for Orion Launch Abort System Control Design Studies

The development and use of an interactive environment to perform control system design and analysis of the proposed Crew Exploration Vehicle Launch Abort System is described. The environment, built using a commercial dynamic systems design package, includes use of an open-source configuration control software tool and a collaborative wiki to coordinate between the simulation developers, control law developers and users. A method for switching between multiple candidate control laws and vehicle configurations is described. Aerodynamic models, especially in a development program, change rapidly, so a means for automating the implementation of new aerodynamic models is described

SIMULATION OF A MULTIPROCESSOR COMPUTER SYSTEM

The introduction of computers and software engineering in telephone switching systems has dictated the need for powerful design aids for such complex systems. Among these design aids simulators - real-time environment simulators and flat-level simulators - have been found particularly useful in stored program controlled switching systems design and evaluation. However, both types of simulators suffer from certain disadvantages. An alternative methodology to the simulation of stored program controlled switching systems is proposed in this research. The methodology is based on the development of a process-based multilevel hierarchically structured software simulator. This methodology eliminates the disadvantages of environment and flat-level simulators. It enables the modelling of the system in a 1 to 1 transformation process retaining the sub-systems interfaces and, hence, making it easier to see the resemblance between the model and modelled system and to incorporate design modifications and/or additions in the simulator. This methodology has been applied in building a simulation package for the System X family of exchanges. The Processor Utility Sub-system used to control the exchanges is first simulated, verified and validated. The application sub-systems models are then added one level higher_, resulting in an open-ended simulator having sub-systems models at different levels of detail and capable of simulating any member of the System X family of exchanges. The viability of the methodology is demonstrated by conducting experiments to tune the real-time operating system and by simulating a particular exchange - The Digital Main Network Switching Centre - in order to determine its performance characteristics.The General Electric Company Ltd, GEC Hirst Research Cent, Wemble

Using C to build a satellite scheduling expert system: Examples from the Explorer platform planning system

Recently, many expert systems were developed in a LISP environment and then ported to the real world C environment before the final system is delivered. This situation may require that the entire system be completely rewritten in C and may actually result in a system which is put together as quickly as possible with little regard for maintainability and further evolution. With the introduction of high performance UNIX and X-windows based workstations, a great deal of the advantages of developing a first system in the LISP environment have become questionable. A C-based AI development effort is described which is based on a software tools approach with emphasis on reusability and maintainability of code. The discussion starts with simple examples of how list processing can easily be implemented in C and then proceeds to the implementations of frames and objects which use dynamic memory allocation. The implementation of procedures which use depth first search, constraint propagation, context switching and a blackboard-like simulation environment are described. Techniques for managing the complexity of C-based AI software are noted, especially the object-oriented techniques of data encapsulation and incremental development. Finally, all these concepts are put together by describing the components of planning software called the Planning And Resource Reasoning (PARR) shell. This shell was successfully utilized for scheduling services of the Tracking and Data Relay Satellite System for the Earth Radiation Budget Satellite since May 1987 and will be used for operations scheduling of the Explorer Platform in November 1991

Analysing the requirements for monitoring and switching: A problem-oriented approach

Context-aware applications monitor changes in their environment and switch their behaviour in order to continue satisfying requirements. Specifying monitoring and switching in such applications can be difficult due to their dependence on varying environmental properties. Two problems require analysis: the detection of changes in the operating environment to assess their impact on requirements satisfaction, and the adaptation of application behaviour to ensure requirements satisfaction. This thesis borrows from the world of problem-oriented software system development and product-lines to analyse monitoring and switching problems on one hand and contextual changes on the other. It proposes a shift of focus from treating monitoring and switching as activities to be analysed as part of the design, to treating them as part of the problem whose requirements are analysed. We claim three novel contributions: (1) we provide concepts and mechanisms for analysing monitoring and switching problems in context; (2) we formulate and prove two theorems for monitoring and switching, which define the necessary and sufficient conditions for monitoring a contextual variable and for switching application behaviour to restore requirements satisfaction when they are violated; and (3) we provide a tool for automated derivation of the conditions for monitoring and switching. Our approach is evaluated using two case studies of a proof of concept mobile phone productline and a logistics company that delivers and monitors products across the UK. We found the applications of the approach to be effective in analysing unforeseen requirements violations caused by changes in the systems operating environments. Furthermore, the monitoring and switching mechanisms derived from the analysis enabled the software to become, to some extent, context-aware

Development of a programmable integrated switch matrix (PRISM).

This research project involved the development of a fully customizable, user-defined hardware-software suite for automated signal routing with function expandability. Because of the above-mentioned characteristics, the project was called Programmable Integrated Switch Matrix (PrISM). This intelligent switching system can be customized and employed in any industry where there is a need for programmable, timed, and/or simultaneous routing of analog or digital signals between devices. Potential applications of these automated switching systems include, but are not limited to: demarcation points, test floors, redundant backup systems, remote maintenance, etc. A suitable test bed for PrISM was found in a collaboration with the Federal Aviation Administration (FAA) Oklahoma Communications Engineering Team (OKCET) Laboratory and has found an immediate potential application as a large-scale switching system. The fundamental hardware unit for this system is the National Instruments (NI) PXI chassis with a NI SwitchBlock populated with matrix relay cards. The chassis can be deployed in any location, contributing to the robust nature of the design. The advantage of using an integrated NI system is its modularity; the hardware can be easily tailored to the specific needs of each end user. Expansion and customization is accomplished with the addition of a wide spectrum of matrix relay cards. Matrix cards are available with a varying number of relays or switching points. The proposed system is controlled and automated by a customized virtual instrument (VI) application software that was developed using NI LabVIEW software environment and can be integrated with the PXI or function as an executable on a standalone desktop computer

PROCESS CONFORMANCE TESTING: A METHODOLOGY TO IDENTIFY AND UNDERSTAND PROCESS VIOLATIONS IN ENACTMENT OF SOFTWARE PROCESSES

Today's software development is driven by software processes and practices that when followed increase the chances of building high quality software products. Not following these guidelines results in increased risk that the goal for the software's quality characteristics cannot be reached. Current process analysis approaches are limited in identifying and understanding process deviations and ultimately fail in comprehending why a process does not work in a given environment and what steps of the process have to be changed and tailored. In this work I will present a methodology for formulating, identifying and investigating process violations in the execution of software processes. The methodology, which can be thought of as "Process Conformance Testing", consists of a four step iterative model, compromising templates and tools. A strong focus is set on identifying violations in a cost efficient and unobtrusive manner by utilizing automatically collected data gathered through commonly used software development tools, such as version control systems. To evaluate the usefulness and correctness of the model a series of four studies have been conducted in both classroom and professional environments. A total of eight different software processes have been investigated and tested. The results of the studies show that the steps and iterative character of the methodology are useful for formulating and tailoring violation detection strategies and investigating violations in classroom study environments and professional environments. All the investigated processes were violated in some way, which emphasizes the importance of conformance measurement. This is especially important when running an empirical study to evaluate the effectiveness of a software process, as the experimenters want to make sure they are evaluating the specified process and not a variation of it. Violation detection strategies were tailored based upon analysis of the history of violations and feedback from then enactors and mangers yielding greater precision of identification of non-conformities. The overhead cost of the approach is shown to be feasible with a 3.4% (professional environment) and 12.1% (classroom environment) overhead. One interesting side result is that process enactors did not always follow the process for good reason, e.g. the process was not tailored for the environment, it was not specified at the right level of granularity, or was too difficult to follow. Two specific examples in this thesis are XP Pair Switching and Test Driven Development. In XP Pair Switching, the practice was violated because the frequency of switching was too high. The definition of Test Driven Development is simple and clear but requires a fair amount of discipline to follow, especially by novice programmers

Software architectural design for safety in Automated Parking System

The automotive industry has seen a revolution brought about by self-driving cars. However, one of the main challenges facing autonomous driving systems is ensuring safety in the absence of a supervising driver and verifying safe vehicle behaviour under various circumstances. Autonomous Driving Systems (ADS), due to their complexity, cannot be solved straightforwardly without proper structure. Thus, they need a well-defined architecture to guide their development with requirements that involve modularity, scalability, and maintainability among other properties. To help overcome some of the challenges, this master thesis defines and implements in a simulated environment an automated parking system that complies with industrial and safety standards. The work has been divided into four parts. Firstly, the safety rules for the development of an autonomous function have been analysed. Secondly, the use cases and system requirements have been defined following the needs of the automated parking system. Thirdly, the system has been implemented in the simulation environment with a structure based on a widely adopted automotive standard. The final result is the software architecture of an autonomous vehicle with automated parking functionality. This concept has been validated within the virtual environment together with the integration of the AUTOSAR runtime environment, which the communication between components and mode switching functionality in the CARLA simulation environment. The result of this project shows the benefit of integrating architecture and simulation, thus easing the development and testing of future autonomous systems

Design implications for task-specific search utilities for retrieval and re-engineering of code

The importance of information retrieval systems is unquestionable in the modern society and both individuals as well as enterprises recognise the benefits of being able to find information effectively. Current code-focused information retrieval systems such as Google Code Search, Codeplex or Koders produce results based on specific keywords. However, these systems do not take into account developers’ context such as development language, technology framework, goal of the project, project complexity and developer’s domain expertise. They also impose additional cognitive burden on users in switching between different interfaces and clicking through to find the relevant code. Hence, they are not used by software developers. In this paper, we discuss how software engineers interact with information and general-purpose information retrieval systems (e.g. Google, Yahoo!) and investigate to what extent domain-specific search and recommendation utilities can be developed in order to support their work-related activities. In order to investigate this, we conducted a user study and found that software engineers followed many identifiable and repeatable work tasks and behaviours. These behaviours can be used to develop implicit relevance feedback-based systems based on the observed retention actions. Moreover, we discuss the implications for the development of task-specific search and collaborative recommendation utilities embedded with the Google standard search engine and Microsoft IntelliSense for retrieval and re-engineering of code. Based on implicit relevance feedback, we have implemented a prototype of the proposed collaborative recommendation system, which was evaluated in a controlled environment simulating the real-world situation of professional software engineers. The evaluation has achieved promising initial results on the precision and recall performance of the system

ROS2 versus AUTOSAR: automated PARKING system case-study

Vehicles are complex systems as they combine several engineering disciplines, such as mechanical, electric, electronic, software and telecommunication. In the last decades, most innovations in the automotive domain have been achieved as a combination of electronics and software. Consequently, the software development and deployment has resulted a highly sophisticated engineering process to manage and to integrate. With the introduction of artificial intelligence, automated driving has become a reality. However it has additionally increased the requirements on the system design. One widely accepted approach to manage complexity is to divide the system into subsystems through a well-defined architecture. The architecture of an autonomous system must be suitable to guarantee that the self-driving functionality remains safe in a broad range of operational domains. The challenge is how to design the architecture of the system to be reliable and resilient to changing context. The automotive industry has well established standards and development practices, but it is open to explore and integrate solutions from other domains like Internet of Things and Robotics. In the area of autonomous systems, the capabilities of the robotics middleware ROS2 have been used for prototyping purposes. It is an open question whether ROS2 is suitable for automotive safety relevant applications. This master thesis addresses this challenge through evaluating the possible application of ROS2 in the automotive domain. The development consists of implementing an architecture for an autonomous driving function case-study, an Automated Parking System, which adapts to its context by switching between different operational modes. The Automated Parking System has been implemented and validated in a simulation environment. The experiment results show which benefits bring ROS2 compared with the automotive standardised architecture AUTOSAR

Haptic/Graphic Rehabilitation: Integrating a Robot into a Virtual Environment Library and Applying it to Stroke Therapy

Recent research that tests interactive devices for prolonged therapy practice has revealed new prospects for robotics combined with graphical and other forms of biofeedback. Previous human-robot interactive systems have required different software commands to be implemented for each robot leading to unnecessary developmental overhead time each time a new system becomes available. For example, when a haptic/graphic virtual reality environment has been coded for one specific robot to provide haptic feedback, that specific robot would not be able to be traded for another robot without recoding the program. However, recent efforts in the open source community have proposed a wrapper class approach that can elicit nearly identical responses regardless of the robot used. The result can lead researchers across the globe to perform similar experiments using shared code. Therefore modular "switching out"of one robot for another would not affect development time. In this paper, we outline the successful creation and implementation of a wrapper class for one robot into the open-source H3DAPI, which integrates the software commands most commonly used by all robots