255 research outputs found
Simulation of Mixed Critical In-vehicular Networks
Future automotive applications ranging from advanced driver assistance to
autonomous driving will largely increase demands on in-vehicular networks. Data
flows of high bandwidth or low latency requirements, but in particular many
additional communication relations will introduce a new level of complexity to
the in-car communication system. It is expected that future communication
backbones which interconnect sensors and actuators with ECU in cars will be
built on Ethernet technologies. However, signalling from different application
domains demands for network services of tailored attributes, including
real-time transmission protocols as defined in the TSN Ethernet extensions.
These QoS constraints will increase network complexity even further.
Event-based simulation is a key technology to master the challenges of an
in-car network design. This chapter introduces the domain-specific aspects and
simulation models for in-vehicular networks and presents an overview of the
car-centric network design process. Starting from a domain specific description
language, we cover the corresponding simulation models with their workflows and
apply our approach to a related case study for an in-car network of a premium
car
Wireless industrial monitoring and control networks: the journey so far and the road ahead
While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks
Using FTT-CAN to the Flexible Control of Bus Redundancy and Bandwidth Usage
DETIController Area Network (CAN) is a popular and very well-known bus system, both in
academia and in industry, initially targeted to automotive applications as a single
digital bus to replace the wiring that were growing complexity, weight and cost with
the advent of new automotive appliances. However, requirements have evolved and
CAN’s dependability and bandwidth limitations led to the emergence of alternative
networks such as FlexRay and TTP/C. Nevertheless, we believe that it is possible to
improve CAN so it could fulfill contemporary requirements. This paper proposes the
use of Flexible Time-Triggered CAN (FTT-CAN) to increase the available bandwidth
while providing fault tolerance in CAN based systems with multiple buses. The
architecture and flexibility of FTT based systems enables a tight yet flexible control of
redundancy and bandwidth usage without increasing the complexity of the nodes. In
this novel solution, a FTT-CAN Master controls the dispatching of messages among a
set of independent buses. The Master can react online to bus failures switching the
transmission of critical messages to a non-faulty bus, always keeping a predetermined
redundancy level
Worst-case response time of aperiodc message in WorldFIP and its improvement in real-time capability
An Approach to remote process monitoring and control
The purpose of this thesis is to present an approach to remote monitoring and operation of distributed real time process control systems. Conventional monitoring of process control systems currently requires a great deal of close supervision from trained personnel located on-site. In many cases, researchers, developers or maintenance personnel cannot be at every location where such a system is installed. Currently, a standardized architecture for remote access to such systems is not available. In addition, most of these systems are very expensive and under-utilized. Researchers would benefit by having access to different parts of a system concurrently The benefits of a layered architecture for remote process monitoring and control will be analyzed through the use of a demonstration system that was realized to examine the real time performance of the interconnection mechanisms between the process controller(s) and the system monitoring interfaces. Low level, real-time process control is achieved by using specialized networking schemes called fieldbusses to interconnect all control devices. In this system, fieldbus controllers will also assume the role of servers connected to the Internet, in order to make device information available to any local or remote clients. In the proposed architecture, remote clients are user interfaces, implemented as JAVA applets, which can be accessed with a web browser. The proposed system architecture allows for client interfaces to gain remote access to various types of fieldbusses transparently
An application of an ethernet based protocol for communication and control in automated manufacturing
The exchange of information in the industrial environment is essential in order to achieve complete integration and control of manufacturing processes. At present the majority of devices present in the shop floor environment are still used as stand alone machines. They do not take advantage of the possibilities offered by a communication link to improve the manufacturing process. The subject of this research has been centered on the development of a simple, flexible and inexpensive support system for communication and control of manufacturing processes. As a result, a system with these features has been proposed and implemented on a simulated workcell. The area footwear manufacturing was chosen for modelling the workcell. The components of the manufacturing support system were developed using an object oriented approach which allowed modularity and software reuse. In order to achieve communication between the components, a communication protocol was developed following the process defined in the rapid protocol implementation framework. Ethernet was selected for implementing the lower levels of the protocol. Java, a new object oriented programming language used for the implementation of the system, showed that it could became a promising language for the implementation of manufacturing applications. In particular the platform independence feature of the language allows the immediate porting of applications to systems with different features. The manufacturing cell simulation had shown that the times associated with the manufacturing support system operations are compatible for its use in applications where the response times are in the order of one second
FTT-Ethernet: A Flexible Real-Time Communication Protocol that Supports Dynamic QoS Management on Ethernet-based Systems
Ethernet was not originally developed to meet the
requirements of real-time industrial automation systems and
it was commonly considered unsuited for applications at the
field level. Hence, several techniques were developed to make
this protocol exhibit real-time behavior, some of them requiring
specialized hardware, others providing soft-real-time guarantees
only, or others achieving hard real-time guarantees with
different levels of bandwidth efficiency. More recently, there has
been an effort to support quality-of-service (QoS) negotiation
and enforcement but there is not yet an Ethernet-based data
link protocol capable of providing dynamic QoS management
to further exploit the variable requirements of dynamic applications.
This paper presents the FTT-Ethernet protocol, which
efficiently supports hard-real-time operation in a flexible way,
seamlessly over shared or switched Ethernet. The FTT-Ethernet
protocol employs an efficient master/multislave transmission
control technique and combines online scheduling with online
admission control, to guarantee continued real-time operation
under dynamic communication requirements, together with data
structures and mechanisms that are tailored to support dynamic
QoS management. The paper includes a sample application,
aiming at the management of video streams, which highlights
the protocol’s ability to support dynamic QoS management with
real-time guarantees
Enhancing real-time CAN communications by the prioritization of urgent messages at the outgoing queue
To ensure the correct behaviour of a Networked Control System, the communication network mustprovide a reliable and timely communication service. The two components with the highest impact on thecommunication delays are the Medium Access Control (MAC) protocol and the local communication stack,therefore, the usage of an adequate communication stack is of utmost importance to guarantee the timingcorrectness of a feedback control application.In this paper, we propose the use of state-of-the-art scheduling algorithms to manage the outgoing queue of alocal communication stack. We demonstrate that it is possible to improve the responsiveness of applicationssupported by the CAN communication protocol, by using just a light scheduling middleware to adequatelyschedule the outgoing queue. We also show that implementing such middleware even on top of COTScommunication hardware, opens the possibility to enhance the communication process by minimizing thenumber of deadline misses for highly loaded network scenarios
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