A comparison of standards for software engineering based on DO-178B for certification of avionics systems

Certification of avionics software is an increasingly important subject, since more and more avionics systems in future aircraft will be software equipped. The DO-17813 standard provides guidelines for software certification. Re-use of software is emerging, partly enabled by the integrated modular avionics concept, and imposed by a reduction of life-cycle costs. Re-use, however, requires re-certification or certification of software that was not developed according to DO-17813.

The DO-178B standard is specially developed to provide a certification basis for avionics software, without going into details of the software development process. Other standards focus on software engineering aspects. We have used the DO-178B standard as a common basis for comparison with DOD-STD2167A (military), ESA PSS-05-0 (space), and IEC65A(Secretariat)122 (industry). Comparison topics include:

• • life cycles;

• • prescribed documentation;

• • configuration management;

• • verification and validation;

• • quality assurance.

All standards prescribe the software development process, emphasizing specific aspects in a certain area of interest. The results of our investigation will assist in understanding the rationale behind several standards, and can be used for:

• • certification according to DO-17813 of software that was developed using another standard;

• • certification of software using DO-17813, in concert with another standard.

     

A Unified, Object-Oriented Graphics System and Software Architecture for Visualising CAD/CAM Presentations

Most object-oriented graphics systems (OOGS) either support general purpose graphics capabilities (drawing editors, ray tracing, etc.), or have targeted specific areas of computer graphics, for example, interface building, animation, and visualisation. However, the key concept in CAD/CAM graphics systems is that of presentations—pictures that convey information about products or parts of products. CAD/CAM graphics systems that create and manipulate presentations have specific graphical requirements that have not been addressed by existing OOGS. These requirements include the support of CAD/CAM concepts such as drawings, views and view-specific graphics, and layers, and the ability to allow external geometric modelers to be linked into the presentation. We describe an object-oriented presentation architecture that allows the application to describe the structure of the CAD/CAM presentation. This architecture provides a unified interface to drawings, views, layers and entities, and allows linkage to models created with an external geometric modeler, while isolating applications from details of the underlying traditional graphics rendering systems. It is our hope that this architecture provide the foundation for the architecture of next generation OOGS. We also present an implementation of this architecture and compare it to other OOGS.     

The BIOPHILE Sample Process Management System - Automated Sample Access at Ultra Low Temperatures

The genomics, proteomics, clinical, and drug discovery laboratories have a growing need to maintain valuable samples at ultra-low (−80°C) temperatures in a validated, secure environment. Automated sample processing systems have until now required manual (off-line) storage of samples at −80°C, reducing system reliability and speed. Both of these important needs are addressed by the Sample Process Management System being introduced by BIOPHILE Inc. Conventional sample management processes, such as storage, retrieval, and cataloging, are increasingly strained by the growing sample populations. There are variable sample types, access requirements and storage requirements. Security and inventory procedures are implemented manually. The evolving technologies present in the laboratory cannot interface with conventional manual storage techniques. Addressing these limitations, the primary benefits of BIOPHILE's solutions are:

• Fully validated sample management process that coordinates the life-cycles of samples and their related data.

• Robotic technology to securely store and retrieve samples, improving their accessibility and stability. Thermal shock is reduced, improving sample longevity and quality. The robotic technology allows integration with larger automation systems.

• A process program to develop a Sample Management Strategy. This strategy is developed by analyzing long-term research goals, current baseline processes, and identification of current sample life cycles. A full validation documentation package can be generated, providing a high level of quality assurance.

• Improved sample visibility and quality assurance - automated sample population cataloging; controlled sample management access and security.

     

A General-Purpose Multi-Microprocessor Raster Graphics Display System with Anti-Aliasing

The raster graphics display system described represents a general purpose mini-computer, specially for CAD applications. The system is based on a hierarchical asynchronous multiple microprocessor system. In practice this mini-computer is extendable up to 15–20 workstations. On the workstations, different graphical and non-graphical devices can be connected. The most interesting workstation is a raster graphics display device which was developed specially for the computer system described. This raster graphics display device contains a processor for the application program, two dedicated processors and two separate identical frame buffers, each of them containing one whole set of image data. Applying algorithms for anti-aliasing, virtual pixel dislocation (intensity dislocation) and multi-pixel-overlappings with hidden line (surface) elimination the image readability and quality can be increased considerably. In particular the paper deals with an anti-aliasing algorithm with a real-time hardware realization.     

Computer-aided robot modeling,programming and simulation

The use of interactive computer graphics for simulation and off line programming provides a powerful tool in implementing robots. This capability essentially became available with the CAD/CAM system.This paper will present the theory of robot modeling and simulation techniques. An overview of CAD/CAM system in robotic application, such as robot off-line programming, simulation and workcell layout will also be represented.     

Something to smile about: 3D graphics are revolutionizing oralhealth care

Computer graphics and all the computer-aided drawing and manufacturing (CAD/CAM), scanning, and imaging technology is changing dentistry. Invisalign is a technology that straightens adult teeth using a series of clear, plastic, nearly invisible aligners. Though proprietary CAD/CAM software that does 3D modeling, the company creates the fixtures for orthodontists. For dental implants dentists make a study cast of the area where the abutment will be placed. They then scan the cast into the computer using a 3D optical scanner, creating a 3D point cloud. Technicians create a polygonal surface from the point cloud. They use proprietary software to virtually assemble the digital teeth data with an unmodified (or template) version of their product. This template is a 3D model of an ideally shaped dental abutment. The computer generates the tool path and sends it to the milling machines that create the titanium abutment. Maxillofacial surgery repairs physical malformations resulting from disease, injury, burns, birth defects, or aging. In these cases, a maxillofacial surgeon must make changes that often include removing bone and replacing it with modeled implants. A surgeon uses computer graphics to solve these problems in his practice. The common thread among the examples of oral health care techniques discussed is the CAD/CAM software they use from Raindrop Geomagic     

Application of design parameters space search for belt conveyor design

Belt conveyor design is examined as an application of a proposed Design Parameters Space Search technique. First, the main characteristics of the belt-conveyor design process are presented as they appear in the current literature. Furthermore, a proposed general knowledge-representation platform is described, and its ability to house the relevant conveyor design knowledge is also shown.

Next, the extended search technique of the design space is discussed, and an integrated example of a belt-conveyor design is presented, based on the proposed representation platform and the extended search technique. Finally, it is shown that the design of belt conveyors according to the proposed approach presents the following significant advantages:

• • Due to the knowledge-representation scheme adopted, both qualitative and quantitative knowledge can be used within the same platform.

• • Multiple solutions can be easily produced through user-defined design criteria. These solutions can be further modified and/or evaluated to produce more-specific designs.

• • The required for user-input data is kept to a minimum. Due to the applied extended search method, semiautomatic design can be achieved. As a consequence, the design process is completed in less time than that required by the conventional methods.

     

An alternative to expert systems for electrical diagnosis

Although the use of an expert system for the detection and location of faults in the power supply subsystem of the TDFI satellite¹ gives good practical results, there are also a certain number of drawbacks:

• - the rules are application-dependent and therefore useless for the diagnosis of other satellites,

• - the amount of knowledge required is quite large and contains a lot of redundant information,

• - testing and updating of the system are tricky,

• - it is far from sure that all possible faults can be taken into account.

The diagnosis theory based on models of correct behavior of the components introduced more recently by de Kleer and Williams seems more suited to this type of problem. Using our program CATS/DIANA, we have been able to validate this approach for analog electronic circuits. We have also tested the method on the diagnosis of satellite power supply subsystems; the results were similar to those obtained using an expert system, but without the drawbacks. This paper describes the two methods and compares the results.     

ATOS — An AI-based space mission operations system

Artificial Intelligence is generally recognised as one of the key technologies for future spaceflight, and a number of ambitious applications for on-board use have been proposed already. Such applications still require a good deal of basic research and development, but on-ground applications could make an impact already in the medium term, and will for some time represent the major part of AI use for space missions.

ESA has started the development of a future integrated and mission-independent spacecraft control data processing system called the Advanced Technology Operations System (ATOS) at the European Space Operations Centre, which will employ artificial intelligence techniques in supporting the operations staff during all mission preparation and implementation phases, in order to cope reliably with complex mission operations and to achieve optimal efficiency in the use of human resources.

ATOS will consist of a number of knowledge based software modules, such as

• Automated mission planning

• Automated operations preparation

• Computer assisted operations

• Advanced operator training,

centred around a Mission Information Base configured for the particular satellite mission, the common data repository for all information required to conduct the mission and operate the spacecraft.

The Mission Information Base will, in addition to numerical data presently found in conventional spacecraft control systems, contain a large amount of ‘knowledge’ about the spacecraft and its mission, which is currently available only in paper documents or embedded in software. It will be implemented as a physically and logically distributed set of databases each representing a particular field of mission information, such that the knowledge can be dynamically shared between different intelligent spacecraft control applications.     

Robot simulator in TIPS/Geometric Simulator

With the growth of factory automation, the need for off-line robot programming is increasing rapidly. Off-line programming requires a robot simulator. This is the reason for the development of a TIPS/GS (Geometric Simulator), accompanied by a robot simulator. TIPS/GS has been developed as a project in the TIPS Research Association. The goal of this project is to extend the functions and applications of the solid modeler TIPS-1. Four simulators (i.e. the assembly simulator, engineering, NC simulator and robot simulator) have been developed for these extended applications.

The robot simulator described in this paper has the following special features:

• • When a robot motion is prescribed by the VAL-G language, the result can be seen on a CRT display in several patterns.

• • High-speed dynamic display which can almost keep up with real-time movements.

• • A shaded as well as wire-frame picture is used for the high-speed display entioned above.

• • Supported by the solid modeler, any robot and environment can be used with this system.

• • The preparation of a precise interference checker based on an analytical methods.

This paper is a report on the development of the robot simulator.     

Implementation procedure of an advanced supervisory and control strategy in the pharmaceutical industry

This paper describes the different steps followed in implementing a temperature controller and a supervisory controller in a Supervisory Control And Data Acquisition (SCADA) system to control a 60 and 160 l reactor in a pharmaceutical factory. These reactors are used to produce the initial quantities of drugs needed to perform clinical tests. The chemical reactions involved are often changed (several times a week). The different steps of the project will be presented:

• design of a new heating–cooling system,

• design of the predictive and Supervisory Control Algorithm (SCA),

• connection of the SCA to the SCADA system,

• experimental validation according to Good Manufacturing Practice (GMP).

This SCA has been in daily use as the standard control system for more than 2 years.     

3D graphics processor chip set

Increasingly, 3D graphics is becoming the rule rather than the exception in applications such as games, CAD/CAM, and video production. Some LSIs provide rendering capabilities, but require an additional CPU to perform essential geometry transformations. Fujitsu's chip set solves that problem using two processors to render 300,000 polygons per second (for flat-shaded triangles with texture)-performance comparable to that of advanced game machines     

ARIANEXPERT: A knowledge based system to analyze ARIANE's mission data

The ARIANE launcher post mission analysis is done at ARIANESPACE. This activity is called the ‘level 0 post flight analysis’ (PFA) and is carried out after each launch by about 60 engineers who are working together under the leadership of ARIANESPACE.

The PFA is one of the most critical of ARIANE operations, for several reasons:

• - The launch rate (8 a year for ARIANE 4) leaves a very short time to carry out all the verification work. Moreover, the PFA is a mandatory step before authorizing the next launch.

• - The complexity of the ARIANE launcher results in a very high demand on the PFA engineers. Moreover, there are problems of availability of people with relevant expert knowledge (characterized by a substantial staff turn-over during the 10 year life duration of ARIANE 4) which could potentially result in errors or omissions.

It is very important to be able to take into account the experience of the preceding flights and to record the results and the knowledge accumulated for each launch.

• - The quality and the reliability of the PFA mainly depends on the accessibility of data and on the used methodology.

Because the PFA is still largely done manually, and does not benefit from improved methodologies and advanced technologies providing computerized support for data processing and diagnosis, ARIANESPACE has sponsored MATRA ESPACE for the development of a knowledge based system, called ARIANEXPERT, for supporting the PFA activity. This system combines AI techniques and numerical analysis techniques, together with advanced graphical capabilities.

A prototype has been delivered in April 1990 and has been used since 6 months by ARIANESPACE during real PFAs. Several lessons have been drawn from this operational experience and are described in this paper. They concern:

• - The utility and justification of the use of AI techniques mostly coming from the explanation capabilities and the stress put on capturing the expert knowledge.

• - The difficulties associated with the integration of such systems in the exploitation of ARIANE due to the introduction of very new tasks.

• - The user point of view which evolved from reluctant to convinced.

     

An image processing approach to computer graphics

Computer graphics was conceived as, and remains for the most part, a line-drawing phenomenon. The cautious management of display lists or of in-line vector generators has captured most of the attention of researchers in computer graphics. Cathode ray tubes with randomly positionable beams have served as the primary medium for this research and development.The underlying position of this paper is that the future of computer graphics does not lie in ‘vectored’ displays but in raster scan television, conceivably as we know it in our homes. This posture is motivated by arguments of cost and compatibility, but the most salient motivation comes in view of the ubiquitous nature of raster scan display technologies.This paper explains a way to implement an image processing approach to computer graphics, one that is conceptually straightforward and, in terms of hardware, fairly easy to design. A device is being built that encompases as much as is known about raster scan, multi-bit per point displays. The work described is conducted, principally, to produce a multi-bit per point graphics output device that dynamically shares its image storage with the memory space of an expanded mini-computer.     

Teaching meshes, subdivision and multiresolution techniques

In recent years, geometry processing algorithms that directly operate on polygonal meshes have become an indispensable tool in computer graphics, CAD/CAM applications, numerical simulations, and medical imaging. Because the demand for people that are specialized in these techniques increases steadily the topic is finding its way into the standard curricula of related lectures on computer graphics and geometric modeling and is often the subject of seminars and presentations. In this article we suggest a toolbox to educators who are planning to set up a lecture or talk about geometry processing for a specific audience. For this we propose a set of teaching blocks, each of which covers a specific subtopic. These teaching blocks can be assembled so as to fit different occasions like lectures, courses, seminars and talks and different audiences like students and industrial practitioners. We also provide examples that can be used to deepen the subject matter and give references to the most relevant work.     

Parallelization of Bresenham's line and circle algorithms

Parallel algorithm for line and circle drawing that are based on J.E. Bresenham's line and circle algorithms (see Commun. ACM, vol.20, no.2, p.100-6 (1977)) are presented. The new algorithms are applicable on raster scan CRTs, incremental pen plotters, and certain types of printers. The line algorithm approaches a perfect speedup of P as the line length approaches infinity, and the circle algorithm approaches a speedup greater than 0.9P as the circle radius approaches infinity. It is assumed that the algorithm are run in a multiple-instruction-multiple-data (MIMD) environment, that the raster memory is shared, and that the processors are dedicated and assigned to the task (of line or circle drawing)     

Some Issues in Designing User Interfaces to 3D Raster Graphics

Now that raster graphics has become a common tool in CAD/CAM systems, animation and many other applications, the need has arisen for user interfaces to graphics packages for these new applications. On the basis of a typology of the users, an analysis is presented of some of the choices which have to be made in developing these interfaces.