Henning Trsek

Cloud computing for industrial automation systems — A comprehensive overview

Cloud computing has recently emerged as a new computing paradigm in many application areas comprising office and enterprise systems. It offers various solutions to provide a dynamic and flexible infrastructure to host computing resources and deliver them as a service on-demand. Since industrial automation systems of the future have to be adaptable and agile, cloud computing can be considered as a promising solution for this area. However, the requirements of industrial automation systems differ significantly from the office and enterprise world. This paper provides an overview of the latest concepts of cloud computing technology for industrial automation. Existing works are categorized based on the levels of automation systems and research gaps are discussed based on these findings. A general cloud model for automation is derived from existing proposals by refining them further. This cloud model will offer automation functions as services from a dynamic infrastructure.

Control-as-a-service from the cloud: A case study for using virtualized PLCs

Cloud computing has recently emerged as a new computing paradigm in many application areas comprising office and enterprise systems. It offers various solutions to provide a dynamic and flexible infrastructure to host computing resources and deliver them as a service on-demand. Since industrial automation systems of the future have to be adaptable and agile, cloud computing can be considered as a promising solution for this area. However, the requirements of industrial automation systems differ significantly from the office and enterprise world. In this paper we describe a case study that implements a concept of PLC as a service within a cloud based infrastructure and provides a performance evaluation with respect to legacy PLCs.

Using OPC-UA for the autoconfiguration of real-time Ethernet systems

In the future, production systems will consist of modular and flexible production components, being able to adapt to completely new manufacturing processes. This requirement arises from market turbulences caused by customer demands, i. e. highly customized goods in smaller production batches, or phenomenon like commercial crisis. In order to achieve adaptable production systems, one of the major challenges is to develop suitable autoconfiguration mechanisms for industrial automation systems. This paper presents a two-step architecture for the autoconfiguration of real-time Ethernet (RTE) systems. As a first step, an RTE-independent device discovery mechanism is introduced. Afterwards, it is shown how the parameters of an RTE can be configured automatically using Profinet IO as an exemplary RTE system. In contrast to the existing approaches, the proposed discovery mechanism is based on the OPC Unified Architecture (OPC-UA). In addition, a procedure to autoconfigure modular IO-Devices is introduced.

Towards autoconfiguration of industrial automation systems: A case study using Profinet IO

Nowadays the deployment and commissioning of complex production processes or Internet-enabled applications interacting with production systems requires a time consuming and error-prone manual system configuration process. This is due to the need to maintain a high level of determinism, safety, and security of the production process itself and avoiding both safety-critical failures and costly production interruptions. The project “IoT@Work - Internet of Things at Work” aims at delivering tools and runtime mechanisms to significantly simplify commissioning, operating, and maintaining complex production processes, thus enabling Plug-and-Produce for automation systems. This paper presents a novel approach for the autoconfiguration of real-time Ethernet systems, and all relevant mechanisms. A case study, based on Profinet IO, evaluates the approach and shows its feasibility.

An isochronous medium access for real-time wireless communications in industrial automation systems - A use case for wireless clock synchronization

Wireless technologies are increasingly deployed in factory automation systems, because they are able to provide several advantages, e. g., a higher level of mobility, more flexibility, and at the same time causing lower costs. However, the requirements of industrial applications in terms of real-time communication can not be satisfied by existing wireless technologies, such as IEEE 802.11Wireless Local Area Networks (WLANs). This is due to their unpredictable behaviour and the introduction of delays beyond acceptable bounds, mainly caused by a non-deterministic medium access. Hence, the proposed wireless communication system provides real-time communication services based on the IEEE 802.11 protocol family. In this paper we present a new isochronous medium access control mechanism, called IsoMAC. The paper addresses IsoMAC and shows how, in combination with a suitable wireless clock synchronization, IsoMAC is able to satisfy the typical constraints of soft real-time flows found on the factory floor. A simulation case study is provided that shows the achievable update times of the proposed combination.

Towards high accuracy in IEEE 802.11 based clock synchronization using PTP

The introduction of the precision time protocol has brought forth the possibility to have a standardised synchronization mechanism in networks, independent from the actual communication technology. However, it can be observed, for example in the annexes of the standard, that many implementations focus only on Ethernet based communication. The logical next step is to investigate how this protocol will fare when used for synchronizing clocks in a distributed manner over IEEE 802.11 based devices. The availability of features like roaming, the broadcast nature of the wireless medium and different hardware platform architectures require an investigation on how clock synchronization can be realized in wireless environments. This paper proposes an approach to import the precision time protocol to IEEE 802.11. Furthermore, standard nodes are enhanced with software timestamping, leading to a synchronization accuracy of a few microseconds.

Agile manufacturing: General challenges and an IoT@Work perspective

This paper describes the potential impact of the Internet of Things (IoT) technologies and architecture on factory automation. Whereas, IoT use cases range from intelligent infrastructure and smart cities to health care and shopping assistants, it is important to note that factory automation could benefit as well from an IoT approach. In this paper, we argue that there will not be one IoT but many IoTs that could differ in the type of infrastructure they are running or applications they support. In IoT@Work we focus on the potential of making manufacturing environments more agile and flexible. We explain how the IoT-centric architecture for manufacturing also needs a deep understanding of the manufacturing system and its state today. We, therefore, do a reverse engineering based on the requirements and the description of the agility expected in the automation system itself.

Performance investigation and optimization of IEEE802.15.4 for industrial wireless sensor networks

This paper evaluates the performance of IEEE 802.15.4 for industrial wireless sensor networks. The IEEE 802.15.4 protocol has got the ability to provide real time data transmission in wireless sensor networks using guaranteed time slots (GTS) as medium access control mechanism. According to the standard, a maximum of 7 GTSs can be allocated in one superframe. All GTSs are exclusively dedicated to a corresponding node. Hence, the GTS mechanism is rather limited regarding the number of nodes and the needed scalability is missing. In this paper we introduce a new scheduling algorithm called ldquoEarliest Due Date GTS Allocationrdquo which can be implemented at the medium access control layer. Using this scheduling scheme and an appropriate scheduler, the GTS mechanism is enhanced, in order to enable a deployment in large scale networks with real-time requirements.

System integration of an IEEE 802.11 based TDoA localization system

Network entities with synchronized clocks are an enabler for many interesting and innovative applications. Localization of mobile WLAN devices by means of propagation delay measurements and position calculation according to time difference of arrival (TDoA) method is one of the most interesting applications. Those localization techniques are favored over standard signal strength based methods when high accuracy positioning is desired. This paper presents a system that utilizes special synchronized receivers in conjunction with a central unit to locate WLAN devices. The system architecture is described in terms of the integration of all participating entities for both, hardware and software. 1

A field level architecture for reconfigurable real-time automation systems

Rapidly changing customer demands lead to a paradigm shift from mass production to mass customization within the manufacturing industry. However, todays production systems are of a very static nature. Changing the manufacturing process requires a high amount of expensive human resources and is quite error prone. Hence, reconfigurability will become a key factor in the manufacturing industry and industrial automation systems must provide suitable solutions to support this new paradigm. Service-oriented architectures (SOAs) are a potential technology which can provide the requested capability of automatic reconfiguration. Originating from the IT world, the adaptation of SOAs to industrial automation systems has to face several difficulties - especially real-time requirements must be met. This paper proposes an innovative solution approach for the integration of a SOA into real-time systems for industrial automation.