Ethernet-based Network Research Articles

Time-Sensitive Networking (TSN) for Industrial Automation: Current Advances and Future Directions

With the introduction of Cyber-Physical Systems (CPS) and Internet of Things (IoT) technologies, the automation industry is undergoing significant changes, particularly in improving production efficiency and reducing maintenance costs. Industrial automation applications often need to transmit time- and safety-critical data to closely monitor and control industrial processes. Several Ethernet-based fieldbus solutions, such as PROFINET IRT, EtherNet/IP, and EtherCAT, are widely used to ensure real-time communications in industrial automation systems. These solutions, however, commonly incorporate additional mechanisms to provide latency guarantees, making their interoperability a grand challenge. The IEEE 802.1 Time-Sensitive Networking (TSN) task group was formed to enhance and optimize IEEE 802.1 network standards, particularly for Ethernet-based networks. These solutions can be evolved and adapted for cross-industry scenarios, such as large-scale distributed industrial plants requiring multiple industrial entities to work collaboratively. This paper provides a comprehensive review of current advances in TSN standards for industrial automation. It presents the state-of-the-art IEEE TSN standards and discusses the opportunities and challenges of integrating TSN into the automation industry. Some promising research directions are also highlighted for applying TSN technologies to industrial automation applications.

Time-triggered scheduling of mixed-critical flows at end-system in asynchronous AFDX avionic network

Avionics Full-DupleX (AFDX) is a switched Ethernet-based network used in modern commercial airplanes for the transmission of command and control avionics flows. These critical flows require deterministic guarantees leading to a lightly loaded network. Aircraft manufacturers envision to carry additional non avionics flows (i.e. video, audio, service) to take advantage of the spare bandwidth. However, it is then compulsory to preserve the real-time guarantees of avionics flows in terms of bounded jitter at the transmitter output and of bounded end-to-end latency. Depending on the type of additional traffic, Quality of Service (QoS) end-to-end guarantees may be offered to the additional flows of lower criticality in terms of reduced delay or bounded jitter for instance. These guarantees can be ensured by scheduling policies at transmitter and switch level. However, an important safety-related constraint is the asynchronous design of avionics distributed systems that prohibits the use of a network-wide synchronization of end systems and switches. Thus, time-triggered networking such as emerging Time-Triggered Ethernet (TTEthernet) or Time-Sensitive Networking (TSN) cannot be leveraged. This paper underlines the benefits of only scheduling flows at the transmitter, which is compatible with the asynchronous safety constraint of avionics systems. We show that it is possible to build a table schedule that carries both critical avionics flows and additional video flows that meet their timing and bandwidth allocation constraints. Therefore, we design scheduling strategies for efficient distribution of flows in the table scheduling whose performance is compared to the optimal schedule minimizing the emission lag of additional flows. Proposed heuristics are constructed such as to favor the network responsiveness for avionics flows thanks to slot over-provisioning. Extensive results on an A350 AFDX industrial configuration show that for a transmitter load of up to 70% of the available bandwidth, the uniform allocation heuristic provides a performance close to optimal in terms of minimum emission lag for additional flows, so offering a practical configuration heuristic to industry.

Digital Substations and IEC 61850: A Primer

Modern electrical substations are managed by intelligent electronic devices communicating through Ethernet-based networks. Because of the highly critical roles of substations, which include safety and protection, electronic devices need to be configured automatically through highly reliable and low-latency networks. This gives substation networks some requirements not addressed by previous industrial network standards. To address these unique challenges, IEC 61850 provides a collection of protocols and a model for the automatic configuration of digital substations. This article briefly overviews this standard and the security efforts to protect substations from attacks.

A novel approach for FPGA-to-server data transmission over an Ethernet-based network using the eXpress Data Path technology

In the context of the upgrade of the Large Hadron Collider at CERN for high-luminosity operation, the particle detectors have to cope with much higher data rates and therefore need to upgrade their data acquisition systems. This upgrade is taken as an opportunity to exchange the currently used highly customized hardware by commercial solutions. Nevertheless, some part of the data processing still needs to be done within Field Programmable Gate Arrays (FPGA), requiring the transfer of data between the FPGAs and the commercial servers. This paper reports on a study of direct data transmission from FPGAs to servers via a commercial network. Large data buffers as required for reliable data-transmission protocols are avoided by using an emerging technique named eXpress Data Path (XDP). Based on XDP, the transmission of 5.2 PB (i.e. 2.92 × 1012 packets) was achieved within 168 h without a single missing packet.

Multi-Objective Optimization for Safety-Related Available E/E Architectures Scoping Highly Automated Driving Vehicles

Megatrends such as Highly Automated Driving (HAD) (SAE ≥ Level 3), electrification, and connectivity are reshaping the automotive industry. Together with the new technologies, the business models will also evolve, opening up new possibilities and new fields of competition. To cope with the ongoing advances, new Electric/Electronic (E/E) architecture patterns are emerging in the sector, distributing the vehicle functions across several processing devices and enhancing the connectivity between them via Ethernet-based networks. Upcoming systems will demand Safety-Related Availability (SaRA) requirements in mixed-critical E/E architectures that challenge the concept of freedom from interference defined in ISO 26262. This work explores the concepts of SaRA system development according to ISO 26262, building a framework based on model-based systems engineering to evaluate feasible next-generation automotive E/E architecture designs with a multi-objective analysis. Additionally, we propose a pattern template for SaRA systems to automate the architecture synthesis. To illustrate the framework created, we evaluate a set of automotive E/E architectures synthesized to support mixed-critical vehicle features, including SaRA SAE Level-3 functions, considering the communication networks’ performance as well as hardware and safety-related development costs. This work presents a methodology for original equipment manufacturers and Tier-1 suppliers that enables them to make the trade-offs arising in the design of E/E architectures based on quantified information.

A Perspective on Ethernet in Automotive Communications—Current Status and Future Trends

Automated driving requires correct perception of the surrounding environment in any driving condition. To achieve this result, not only are many more sensors than in current Advanced Driver Assistant Systems (ADAS) needed, but such sensors are also of different types, such as radars, ultrasonic sensors, LiDARs, and video cameras. Given the high number of sensors and the bandwidth requirements of some of them, high-bandwidth automotive-grade networks are required. Ethernet technology is a suitable candidate, as it offers a broad selection of automotive-grade Ethernet physical layers, with transmission speeds ranging from 10 Mbps to 10 Gbps. In addition, the Time-Sensitive Networking (TSN) family of standards offers several features for Ethernet-based networks that are suitable for automotive communications, such as high reliability, bounded delays, support for scheduled traffic, etc. In this context, this paper provides an overview of Ethernet-based in-car networking and discusses novel trends and future developments in automotive communications.

Utilization of SDN Technology for Flexible EtherCAT Networks Applications

At the beginning of the current century, Ethernet-based communication networks began to be implemented in industrial applications. Some previously used protocols were migrated to Ethernet networks, while many others were strictly developed for this communication medium. Numerous industrial Ethernet protocols do not deliver all the capabilities provided by the Ethernet. For example, limitations may arise associated with wireless communication, use of dedicated switching devices, or operation solely for certain topologies. On the other hand, new technologies are now available, such as software defined networks (SDN), that add new features to Ethernet-based communication systems. In this paper, an EtherCAT network in combination with SDN is analyzed. EtherCAT network may only consist of devices with an implemented EtherCAT protocol stack. Therefore, regular Ethernet switches cannot typically be used in this network and, hence, special network infrastructure may be required to create topologies other than standard line topology. It is shown, however, that this limitation can be overcome by the application of SDN. In addition, a definition of datagram forwarding rules (called SDN flows here) is given, and we demonstrate that EtherCAT datagrams can be sent through routes that are required for proper EtherCAT network operation.

Signal Processing Platform for Long-Range Multi-Spectral Electro-Optical Systems.

In this paper, we present a hardware and software platform for signal processing (SPP) in long-range, multi-spectral, electro-optical systems (MSEOS). Such systems integrate various cameras such as lowlight color, medium or long-wave-infrared thermal and short-wave-infrared cameras together with other sensors such as laser range finders, radars, GPS receivers, etc. on rotational pan-tilt positioner platforms. An SPP is designed with the main goal to control all components of an MSEOS and execute complex signal processing algorithms such as video stabilization, artificial intelligence-based target detection, target tracking, video enhancement, target illumination, multi-sensory image fusion, etc. Such algorithms might be very computationally demanding, so an SPP enables them to run by splitting processing tasks between a field-programmable gate array (FPGA) unit, a multicore microprocessor (MCuP) and a graphic processing unit (GPU). Additionally, multiple SPPs can be linked together via an internal Gbps Ethernet-based network to balance the processing load. A detailed description of the SPP system and experimental results of workloads for typical algorithms on demonstrational MSEOS are given. Finally, we give remarks regarding upgrading SPPs as novel FPGAs, MCuPs and GPUs become available.

Synchronization of Electrical Drives via EtherCAT Fieldbus Communication Modules

Synchronization between devices (in particular drive systems) is paramount for multi-axis motion control systems used in Computerized Numerical Control (CNC) machines, robots, and specialized technology machines used in many areas of the manufacturing industry. EtherCAT is an Ethernet-based network that is one of the most popular industrial networks for multi-axis motion control systems. EtherCAT is standardized in the IEC 61158 and IEC 61784 standards. In the article, an EtherCAT communication network for electrical drives is presented. The article focuses on the synchronization in the EtherCAT network consisting of one master device and slave servo drive devices. Special attention is given to synchronization mechanisms in EtherCAT, such as distributed clocks in slave servo drives devices. For this purpose, a laboratory stand was built consisting of two prototype servo drive devices with BLDC motors equipped with EtherCAT communication modules. A description of the working developed EtherCAT communication modules is given. Authors in communication modules ware used an EtherCAT Slave Controller (ESC) chip (AX58100) to implement lower EtherCAT layers. EtherCAT application layer was implemented in software form on a 32-bit microcontroller, based on CANopen over EtherCAT (CoE) CAN in Automation 402 (CiA402) profile. This research’s main contribution was to show the time dependencies regarding synchronization in terms of data flow in the EtherCAT communication stack in slave servo drive devices. The research results showed that the synchronous operation of drives is mainly influenced not by the mechanism of distributed clocks that ensures synchronization in the EtherCAT network but the implementation of the highest layer of the communication stack in slave servo drive devices. Experimental results are presented that prove the modules’ adequacy for use in high-performance motion control systems.

Transcarotid access for remote robotic endovascular neurointerventions: a cadaveric proof-of-concept study.

The purpose of this proof-of-concept study was to demonstrate the setup and feasibility of transcarotid access for remote robotic neurointerventions in a cadaveric model. The interventional procedures were performed in a fresh-frozen cadaveric model using an endovascular robotic system and a robotic angiography imaging system. A prototype remote, robotic-drive system with an ethernet-based network connectivity and audio-video communication system was used to drive the robotic system remotely. After surgical exposure of the common carotid artery in a cadaveric model, an 8-Fr arterial was inserted and anchored. A telescopic guiding sheath and catheter/microcatheter combination was modified to account for the "workable" length with the CorPath GRX robotic system using transcarotid access. To simulate a carotid stenting procedure, a 0.014-inch wire was advanced robotically to the extracranial internal carotid artery. After confirming the wire position and anatomy by angiography, a self-expandable rapid exchange nitinol stent was loaded into the robotic cassette, advanced, and then deployed robotically across the carotid bifurcation. To simulate an endovascular stroke recanalization procedure, a 0.014-inch wire was advanced into the proximal middle cerebral artery with robotic assistance. A modified 2.95-Fr delivery microcatheter (Velocity, Penumbra Inc.) was loaded into the robotic cassette and positioned. After robotic retraction of the wire, it was switched manually to a mechanical thrombectomy device (Solitaire X, Medtronic). The stentriever was then advanced robotically into the end of the microcatheter. After robotic unfolding and short microcatheter retraction, the microcatheter was manually removed and the stent retriever was extracted using robotic assistance. During intravascular navigation, the device position was guided by 2D angiography and confirmed by 3D cone-beam CT angiography. In this proof-of-concept cadaver study, the authors demonstrated the setup and technical feasibility of transcarotid access for remote robot-assisted neurointerventions such as carotid artery stenting and mechanical thrombectomy. Using transcarotid access, catheter length modifications were necessary to achieve "working length" compatibility with the current-generation CorPath GRX robotic system. While further improvements in dedicated robotic solutions for neurointerventions and next-generation thrombectomy devices are necessary, the transcarotid approach provides a direct, relatively rapid access route to the brain for delivering remote stroke treatment.

Achieving safety and performance with reconfiguration protocol for ethernet TSN in automotive systems

Application of Ethernet-based networks in the autonomous and automated vehicles requires safe and efficient resource management policy. The network components must not only handle high volume of sensor data but also safely accommodate dynamics in system behavior, e.g. detect permanent failures, switch between different driving modes (city/highway), incorporate car-2-x communication etc. This is currently manageable only by using static network configuration, due to the safety concerns, leading to resource overprovisioning under almost all conditions or unfulfilled design requirements. In this work we present an alternative solution which, through protocol-based synchronization and fine-grained re-configuration, allows traffic isolation, fault recovery and controlled adjustments of network performance. This enables cost saving, multi-mode network functionality at low overhead as well as new system functions and improved user experience by dynamic over-the-air network operation. We offer a detailed evaluation of our approach in a demonstrator setup as well as a simulation and comparison with state-of-the-art approaches.

The novel transmission scheme with CAT Ethernet cable and SFP for White Rabbit

White Rabbit (WR) is a deterministic Ethernet-based network for general-purpose data transfer and sub-nanosecond time synchronization in large distributed systems. WR has been used in Large Hadron Collider and Large High-Altitude Air Shower Observatory for physics experiment. WR mainly uses the optical fiber for data transmission between WR devices. Commercial off-the-shelf Direct Attach Cable is not suitable for WR network at 100 m level distance. Considering the lower cost of Category (CAT) Ethernet cable compared to optical fiber and the demand of remote power supply in distributed system at 100 m level length, we developed a novel transmission scheme with CAT Ethernet cable for WR. The novel transmission scheme uses the CAT Ethernet cable and small form-factor pluggable connector which is compatible with the optical links. This scheme only uses two pairs of twisted lines in the CAT Ethernet cable for data uplink and downlink. The other two pairs of twisted lines are used for remote power supply. The novel transmission scheme could use the CAT Ethernet cable to complete remote power supply and time synchronization with expected time offset of less than 100 ps and standard deviation of less than 20 ps in the WR distributed system. The distance of distributed nodes could be 80 m with one CAT 7 Ethernet cable or 150 m with relay transceiver connecting two CAT 7 Ethernet cables. In the short-distance scenarios, the novel transmission scheme has lower cost than the optical fiber and additional power supply function.

Convolutional neural network-based intrusion detection system for AVTP streams in automotive Ethernet-based networks

Connected and autonomous vehicles (CAVs) are an innovative form of traditional vehicles. Automotive Ethernet replaces the controller area network and FlexRay to support the large throughput required by high-definition applications. As CAVs have numerous functions, they exhibit a large attack surface and an increased vulnerability to attacks. However, no previous studies have focused on intrusion detection in automotive Ethernet-based networks. In this paper, we present an intrusion detection method for detecting audio-video transport protocol (AVTP) stream injection attacks in automotive Ethernet-based networks. To the best of our knowledge, this is the first such method developed for automotive Ethernet. The proposed intrusion detection model is based on feature generation and a convolutional neural network (CNN). To evaluate our intrusion detection system, we built a physical BroadR-Reach-based testbed and captured real AVTP packets. The experimental results show that the model exhibits outstanding performance: the F1-score and recall are greater than 0.9704 and 0.9949, respectively. In terms of the inference time per input and the generation intervals of AVTP traffic, our CNN model can readily be employed for real-time detection.

Toward a Substation Automation System Based on IEC 61850

With the global trend to digitalize substation automation systems, International Electro technical Commission 61850, a communication protocol defined by the International Electrotechnical Commission, has been given much attention to ensure consistent communication and integration of substation high-voltage primary plant assets such as instrument transformers, circuit breakers and power transformers with various intelligent electronic devices into a hierarchical level. Along with this transition, equipment of primary plants in the switchyard, such as non-conventional instrument transformers, and a secondary system including merging units are expected to play critical roles due to their fast-transient response over a wide bandwidth. While a non-conventional instrument transformer has advantages when compared with the conventional one, extensive and detailed performance investigation and feasibility studies are still required for its full implementation at a large scale within utilities, industries, smart grids and digital substations. This paper is taking one step forward with respect to this aim by employing an optimized network engineering tool to evaluate the performance of an Ethernet-based network and to validate the overall process bus design requirement of a high-voltage non-conventional instrument transformer. Furthermore, the impact of communication delay on the substation automation system during peak traffic is investigated through a detailed simulation analysis.

Virtualization of Industrial Real-Time Networks for Containerized Controllers.

The virtualization technology has a great potential to improve the manageability and scalability of industrial control systems, as it can host and consolidate computing resources very efficiently. There accordingly have been efforts to utilize the virtualization technology for industrial control systems, but the research for virtualization of traditional industrial real-time networks, such as Controller Area Network (CAN), has been done in a very limited scope. Those traditional fieldbuses have distinguished characteristics from well-studied Ethernet-based networks; thus, it is necessary to study how to support their inherent functions transparently and how to guarantee Quality-of-Service (QoS) in virtualized environments. In this paper, we suggest a lightweight CAN virtualization technology for virtual controllers to tackle both functionality and QoS issues. We particularly target the virtual controllers that are containerized with an operating-system(OS)-based virtualization technology. In the functionality aspect, our virtualization technology provides virtual CAN interfaces and virtual CAN buses at the device driver level. In the QoS perspective, we provide a hierarchical real-time scheduler and a simulator, which enable the adjustment of phase offsets of virtual controllers and tasks. The experiment results show that our CAN virtualization has lower overheads than an existing approach up to 20%. Moreover, we show that the worst-case end-to-end delay could be reduced up to 78.7% by adjusting the phase offsets of virtual controllers and tasks.

Hardware Support to Minimize the End-to-End Delay in Ethernet-Based Ring Networks

Ethernet is a popular networking technology in factory automation and industrial embedded systems, frequently using a ring topology for improved fault-tolerance. As many applications demand ever shorter cycle times and a higher number of nodes, the popular ring endure to remain as a valid topology. In this work, we discuss the factors that determine the ring network delay and show how they affect the network cycle time. Since increasing the link capacity has limited reach, we explore a time-triggered protocol that brings the nodes forwarding delay near to the physical layer delay. Additionally, we propose hardware accelerators based on FPGA technology that minimise the packet reception delay from physical reception to delivery to an application handler, preserving Ethernet layers and being compatible with its standard. This paper explains the accelerators concept and implementation, presents measurements using standard Media Access Control implementations, and shows the solution effectiveness with experimental results. We achieved a delay, from physical reception to the triggering of a user-level handler, of 1.1 µs independent of the packet length.

Ethernet-based Network Architectures for Future Real-time Systems in the Car

Ethernet-based Network Architectures for Future Real-time Systems in the Car

A Perspective on IEEE Time-Sensitive Networking for Industrial Communication and Automation Systems

Networks are a core element of many industrial and automation systems at present. Often these networks transport time- and safety-critical messages that control physical processes. Thus, timely and guaranteed delivery is an essential property of networks for such critical systems. Over the past decade, a variety of network solutions have evolved to satisfy said properties. However, these solutions are largely incompatible with each other and many system architects are forced to deploy different solutions in parallel due to their different capabilities. IEEE 802.1 Time-Sensitive Networking (TSN) is a standardization group that enhances IEEE networking standards, most prominently Ethernet-based networks, with said properties and has the unique potential to evolve as a cross-industry mainstream networking technology. In this survey paper, we give an overview of TSN in industrial communication and automation systems and discuss specific TSN standards and projects in detail as well as their applicability to various industries.

Impact of time-triggered transmission window placement on rate-constrained traffic in TTEthernet networks

Safety-critical Ethernet-based networks are receiving significant attention in avionics, automotive and industrial domains. Time-Triggered Ethernet (TTEthernet AS6802) provides safety-critical transmission guarantees via a high priority, time-triggered (TT) traffic class and a lower priority, rate-constrained (RC) traffic class. TT traffic is transmitted between synchronized nodes of a TTEthernet network in offline scheduled TT transmission windows. In this work, we analyze the impact of different placement strategies for these TT transmission windows on end-to-end delay and jitter of RC messages on the same path segment. We show that, depending on the placement of TT transmission windows in a schedule, the end-to-end delay and jitter of RC messages can vary significantly. We further introduce link-based offsets, a new placement strategy for TT transmission windows which allows to reduce the impact of TT transmission windows on RC traffic. In this strategy offsets are applied to all TT transmission windows in a physical link schedule to reduce the amount of time that an RC message on the same physical link is delayed by TT traffic. The link-based offsets strategy can be implemented in the TTEthernet scheduler and does not require hardware modifications. We show that the link-based offset strategy can reduce the end-to-end delay and jitter of RC traffic, and evaluate our claims using an OMNET++ simulation.

On the Utilization of System-on-Chip Platforms to Achieve Nanosecond Synchronization Accuracies in Substation Automation Systems

A synchronized common sense of time is a key factor for many smart grid applications, such as the sample value process bus operation. The precision time protocol (PTP), as defined in IEEE 1588-2008 standard, is highly recommended for substation communication networks, because it enables synchronization accuracies in the nanoseconds range through conventional Ethernet-based networks. This paper explores the implementation of PTP functionalities on new Xilinx Zynq-7000 all programmable system-on-chip (SoC) device. Different PTP master and slave implementations have been analyzed taking benefit from the flexibility of the SoC all programmable devices. The explored features go from simple only-software versions aided by PTP support of Gigabit Media Access Controllers (GMACs)embedded in the processor section to high-accuracy solutions that include custom PTP hardware in the logic section of the device. For each configuration approach, two different experimental setups based on two Zynq commercial low-cost boards has been built, and the protocol performance has been evaluated by measuring time offset between the pulse per second output signals of the master and the synchronized slave. The results obtained from this analysis show excellent accuracy results, with time offsets in the range of 40 ns and standard deviations of less than 10 ns.