When dealing with distributed control systems, the notions of nodes, messages, timetables, etc. a... more When dealing with distributed control systems, the notions of nodes, messages, timetables, etc. are usually not transparent from the control application designer view. For that reason, in the IFATIS platform, the distributed shared memory model has been introduced to decouple the control application design from the issues of the hardware implementation.
Dealing with tasking overload in object oriented real-time applications design
This paper deals with the overload caused by excessive service requests from the environment for ... more This paper deals with the overload caused by excessive service requests from the environment for dynamic control systems. A method of providing gracefully degraded solutions is proposed, based on the previous work on the project dealing with the design of a consistent embedded real-time control system with the goal of increasing its dependability. A syntax is defined as an enhancement of the object oriented extension of a standard real-time programming language. Further, the task program execution times are estimated for possible execution paths, providing the necessary basis for schedulability analysis in both normal and critical operation modes
In the paper the possibility of using a real-time programming language to formulate hardware and ... more In the paper the possibility of using a real-time programming language to formulate hardware and software speci cations is elaborated. Instead of using strict formal speci cations, a system is described in a simple and straight-forward manner, using terminology which is close to the application programmer and his or her way of thinking. The description is a mixture of clauses in syntactically correct formal notation and natural language inserts. The speci cations are then re ned in a stepwise manner until a program in the real-time programming language miniPEARL is obtained. Its syntax is based on the PEARL for Distributed Systems standardised language. Certain constructs of PEARL are renounced and some others are added to support the necessary features of a consistent hardware model to be employed in real-time control.
This paper gives an overview of a holistic project dealing with the consistent design of embedded... more This paper gives an overview of a holistic project dealing with the consistent design of embedded control systems falling into the first level of safety integrity requirements (SIL l) . It shows how existing methods can be adapted and reasonably employed, whenever possible, without having to resort to new innovations. Firstly, the hardware issues are dealt with and extensively elaborated, particularly the peripheral interfaces with integrated processing capabilities. Secondly, the proven correct real-time operating system executing on its own dedicated processor is briefly addressed, and finally, programming issues including descriptions of the specific programming language, time bounded handling of exceptions, and how to deal with temporal overload.
In contrast to most of the other studies which only consider selected topic(s) and typically deal... more In contrast to most of the other studies which only consider selected topic(s) and typically deal with issues of higher levels of design, the research project outlined in this paper is using a holistic approach to real-time application design issues, It is set up in layers starting with a predictably behaving computer hardware architecture, followed b y an appropriate programming language and, finally, a tool for automated application development. Each of these layers is providing a sound basis for the next higher one.
Although the domain of hard real-time systems has been thoroughly elaborated in the academic sphe... more Although the domain of hard real-time systems has been thoroughly elaborated in the academic sphere, embedded computer control systems –- being an important component in mechatronic designs –- are seldom dealt with consistently. Often, off-the-shelf computer systems are used, with no guarantee that they will be able to meet the requirements specified. In this paper, a design for embedded control systems is presented. Particularly, the paper deals with the hardware architecture and design details, the operating system, and high-level real-time language support. It is shown how estimates of process run-times necessary for schedulability analysis can be acquired on the basis of deterministic behavior of the hardware platform.
Towards Standard-Based Specification and Design of Embedded Real-Time Systems
Real-time Systems and embedded systems in particular have, until recently, been built as works of... more Real-time Systems and embedded systems in particular have, until recently, been built as works of art. Standard hardware components only are now being used and scalable standardized operating systems are being built. There have been many attempts to simplify the design of these systems through the use of standard mechanisms and components, but many have failed due to the specific
To ensure temporally predictable execution behaviour of an embedded hard realtime computer contro... more To ensure temporally predictable execution behaviour of an embedded hard realtime computer control system, layer-by-layer predictability of the system must be provided. Based on a simple structured programming language, a programming environment for hard real-time applications is under construction designed to function temporally predictably, and to support an experimental hardware platform as well as a corresponding operating system. A compiler with an integrated analyser for execution-time analysis of tasks is used to determine usable, realistic and not too pessimistic run-time estimates.
The goal of this paper is to find the most efficient architecture for distributed and adaptive sy... more The goal of this paper is to find the most efficient architecture for distributed and adaptive systems that could provide services, which have to be executed within a given time frame. A real-time client/server architecture is proposed. This paper focuses on the server part of the architecture, the real-time server object (RTSO). Within this architecture, a client communicates with a local proxy object, which acts as a representative of one remote RTSO. The software architecture for a RTSO is based upon a reflective architecture. A metaobject controls the application and one object provides the services issued from the client request, which include some real-time constraints. The hardware architecture for a RTSO is a multiprocessor architecture in which processors are dedicated to the metaobject and the object respectively. Within the same server site, a metaobject (function and data members) is mapped onto dedicated processors named kernel processors; the methods (function members) are mapped onto task processors. Depending on their use, the attributes (data members) are mapped onto task, kernel processors or onto a real-time shared memory. Finally, the real time temporal performance of such a complex architecture is evaluated
Although the domain of hard real-time systems has been thoroughly elaborated in the academic sphe... more Although the domain of hard real-time systems has been thoroughly elaborated in the academic sphere, embedded computer control systems — being an important component in mechatronic designs — are seldom dealt with consistently. Often, off-the-shelf computer systems are used, with no guarantee that they will be able to meet the requirements specified. In this paper, a design for embedded control systems is presented. Particularly, the paper deals with the hardware architecture and design details, the operating system, and high-level real-time language support. It is shown how estimates of process run-times necessary for schedulability analysis can be acquired on the basis of deterministic behavior of the hardware platform.
Journal of Computing and Information Technology, 2000
In the paper some experiences of joining two methodologies, which were originally independently d... more In the paper some experiences of joining two methodologies, which were originally independently developed in different institutions, with the goal to overcome the possible discrepancies due to the separate design of the hardware and the software part of an embedded real-time application are presented.
The paper describes the result of our research in automating the software developing processa CAS... more The paper describes the result of our research in automating the software developing processa CASE environment named RBT. The environment supports the rapid prototyping approach to software development. I t allows the analyst to describe both, the statical model and the dynamical model by means of the same conceptual toolmodified DFDs. Thus, no transformation is necessary to be performed at the proceeding from the description of statical model to dynamical model. This provides simple and fast management of the developing process although it contains a lot of iterations. The control algorithm is described implicitly by means of activation conditions of each system process. It is not necessary t o describe all system states and events or the whole control algorithm of a system. The similar computing principle to the data flow computing is used for the execution of the described system specificationan operational prototype of a system.
The CASE tool RPT supporting the rapid prototyping approach to software development
Results are presented of research in automating the software development process by means of a ra... more Results are presented of research in automating the software development process by means of a rapid prototyping approach supported by a RPT (rapid prototyping tool) environment that is being built. The tool allows the analyst to describe both the static model and the dynamic model by means of the same graphical and textural techniques. The control algorithm is described implicitly by means of activating conditions of each system process
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