Federico Tramarin | Università degli studi di Modena e Reggio Emilia (original) (raw)

Papers by Federico Tramarin

2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2020

The Industrial IoT scenario represents an interesting opportunity for distributed measurements sy... more The Industrial IoT scenario represents an interesting opportunity for distributed measurements systems, that are typically based on efficient and reliable communication systems, as well as the widespread availability of data from measurement instruments and/or sensors. The Open Platform Communications (OPC) Unified Architecture (UA) protocol is designed to ensure interoperability between heterogeneous sensors and acquisition systems, given its object–oriented structure allowing a complete contextualization of the information. Stemming from the intrinsic complexity of OPC UA, we designed an experimental measurement setup to carry out a meaningful performance assessment of its main open source implementations. The aim is to characterize the impact of the adoption of this protocol stack in a DMS in terms of both latency and power consumption, and to provide a general yet accurate and reproducible measurement setup.

IEEE Transactions on Industrial Informatics, 2020

In this article, we investigate an innovative solution, to implement high sampling frequency indu... more In this article, we investigate an innovative solution, to implement high sampling frequency industrial control by means of networked embedded systems connected via WiFi. The basic idea relies on a co-design approach for the control application, which is then able to adapt its sampling period, as well as to tune the Wi-Fi parameters, according to the feedback coming from the network. To this end, we implemented a cross-layer architecture acting at both application and data-link layers, which features a robust frame-delay state estimator, a time-efficient communication policy, and a specific tuning of the critical protocol parameters. Suitable hardware-in-the-loop experiments have been carried out exploiting two different embedded systems available off-the-shelf. The preliminary results, obtained from an extensive experimental campaign, are encouraging since they show that the proposed architecture enables industrial control applications requiring a sampling rate up to 1000 Hz, even in presence of communication impairments.

2019 18th European Control Conference (ECC), 2019

Wireless communication is a very appealing technology for industrial automation and networked con... more Wireless communication is a very appealing technology for industrial automation and networked control systems but much more unreliable as compared to wired solutions. Existing wireless standards for industrial automation such as ISA100 and WirelessHart address such unreliability but are limited to low control rates not exceeding 20 Hz, which are suitable for supervisory tasks, but not for high-bandwidth applications. In this work, we propose to use Wi-Fi, which thanks to its high data rates (> 300 Mbit/s), seems to be eligible for high performance applications requiring control rates greater than 1 kHz. Preliminary works mostly rely on emulation approaches, in which no change in the control design is needed, but the communication protocols have to be modified to enforce determinism (e.g. via TDMA-like protocols) at the price of longer delays. Conversely, this work follows a different paradigm, where the unreliability of the communication, due to random packet losses and delays, is coped by a robust model-based controller, which is capable of dealing with the stochastic nature of the communication channel while guaranteeing high control rates. The proposed approach has been tested on a hardware-in-the-loop laboratory setup involving conventional off-the-shelf Wi-Fi network interface cards, which showed how control rates in the order of 1 kHz are well within the possibility of Wi-Fi, even in the presence of substantial communication channel noise.

2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC)

The continuous evolution of additive manufacturing allows to produce innovative objects that are ... more The continuous evolution of additive manufacturing allows to produce innovative objects that are adopted in several diverse fields of applications. This trend can be further enhanced by the spreading of the Industrial Internet of Things (IIoT) paradigm which ensures effective interconnection among distributed, possibly heterogeneous, components and allows remote access by means of commercial devices such as PCs, tablets and smartphones. In this paper, we address a large additive manufacturing project which effectively exploits an IIoT architecture by embedding sensors (temperature, humidity, light, etc.) within the produced artifacts, so that they can make available diverse measurement data collected during both the production process (in real–time) and the subsequent lifetime of the artifacts, enabling further off–line analyses. This clearly represents an innovative and challenging feature that needs to be adequately investigated. To this regard, after describing the automation system of the project, we focus on the wireless system that implements the collection of measurements by the sensors within the artifacts. The design process led to the selection of a Low Power Wide Area Network, namely LoRaWAN, as a suitable communication solution. In this respect, we present here the tests performed to assess the actual feasibility and performance of such network in this specific application context. The obtained results are encouraging, since the sensors within the artifacts revealed able to exchange the required measurement data with the automation system in an effective way.

2020 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)

Wireless technologies play a key role in the Industrial Internet of Things (IIoT) scenario, for t... more Wireless technologies play a key role in the Industrial Internet of Things (IIoT) scenario, for the development of increasingly flexible and interconnected factory systems. Wi-Fi remains particularly attracting due to its pervasiveness and high achievable data rates. Furthermore, its Rate Adaptation (RA) capabilities make it suitable to the harsh industrial environments, provided that specifically designed RA algorithms are deployed. To this aim, this paper proposes to exploit Reinforcement Learning (RL) techniques to design an industry-specific RA algorithm. The RL is spreading in many fields since it allows to design intelligent systems by means of a stochastic discrete–time system based approach. In this work we propose to enhance the Robust Rate Adaptation Algorithm (RRAA) by means of a RL approach. The preliminary assessment of the designed RA algorithm is carried out through meaningful OMNeT++ simulations, that allow to recognize the beneficial impact of the introduction of RL with respect to several industry-specific performance indicators.

2020 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)

Modern industrial manufacturing plants, especially those using coordinated electrical drives with... more Modern industrial manufacturing plants, especially those using coordinated electrical drives with strict timing requirements, make extensive use of real-time communication networks. These systems, typically, are based on various topologies, include diverse protocols, and connect devices from different manufacturers, which may make them difficult to study, plan and optimize. As a solution, the adoption of digital twins allows to simulate such systems under various operating conditions in a low-cost and zero-risk environment. In this paper we address the digital twin of a networked electrical drive system, focusing on the real-time communication network used to connect the drives. In particular, we describe the simulation model of Profinet IO RT Class 1, implemented as an extension of the INET library of OMNeT++. Moreover, we present the outcomes of the tests carried out on a prototype simulated network and compare them with those of the equivalent real one.

2019 Design, Automation & Test in Europe Conference & Exhibition (DATE)

People affected by the Parkinson's disease are often subject to episodes of Freezing of Gait (FoG... more People affected by the Parkinson's disease are often subject to episodes of Freezing of Gait (FoG) near specific areas within their environment. In order to prevent such episodes, this paper presents a low-cost indoor localization system specifically designed to identify these critical areas. The final aim is to exploit the output of this system within a wearable device, to generate a rhythmic stimuli able to prevent the FoG when the person enters a risky area. The proposed localization system is based on a classification engine, which uses a fingerprinting phase for the initial training. It is then dynamically adjusted by exploiting a probabilistic graph model of the environment.

Ethernet POWERLINK (EPL) represents a prominent example of real-time Ethernet (RTE) communication... more Ethernet POWERLINK (EPL) represents a prominent example of real-time Ethernet (RTE) communication networks. It belongs to the IEC 61784 International Standard [1], where it is referred to as the Communication Pro\ua9le (CP) #1 within the CP Family #13

2017 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2017

In this work we aim at providing an initial analysis of the IEEE802.11s amendment that introduced... more In this work we aim at providing an initial analysis of the IEEE802.11s amendment that introduced support for mesh networking to Wireless LAN specifications. Indeed, there has been an increasing interest in the adoption of IEEE 802.11-based wireless systems also in the field of Distributed Measurement Systems (DMSs). Nonetheless, in such a scenario it is necessary to investigate the obtainable performance, in terms of latency, reliability and throughput. Toward this goal, we firstly considered the public available ns-3 IEEE 802.11s model, highlighting some details of the implemented design and also showing some of the unsupported features and open issues. Subsequently, we also leveraged on the mac80211 network emulation features embedded within the Linux kernel to test the mesh extensions included in Linux systems. Finally, using low-cost COTS hardware, exploiting the same mesh stack, we developed a real-world test bench allowing an experimental performance assessment. Results obtained from the presented setups are thus compared, and some open issues are finally discussed.

2020 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2020

In this paper we consider an Industrial Internet of Things (IIoT) system, based on the production... more In this paper we consider an Industrial Internet of Things (IIoT) system, based on the production of 3D–printed artifacts that are equipped with embedded sensors to monitor some environmental variables such as temperature, humidity, etc. These sensors allow to gather information during the production phase of the artifacts, as well as while they are deployed in their final locations, so that diverse operations (e.g. tuning of the production parameters, predictive maintenance, environmental monitoring) can be undertaken. Monitoring is implemented via LoRaWAN, a Low Power Wide Area Network (LPWAN) that allows to acquire data from the sensors embedded in the artifacts. After a description of the IIoT system, we provide the description of some experimental tests we carried out in this challenging context, aimed at investigating both the reliability of the transmission and the battery life time. The outcomes of such experiments indicate the actual feasibility of the proposed technique.

2019 IEEE 17th International Conference on Industrial Informatics (INDIN), 2019

Networked embedded systems for industrial control based on wireless support provide several advan... more Networked embedded systems for industrial control based on wireless support provide several advantages over wired counterparts, but often reveal unsuitable for the most demanding industrial control applications, such as advanced manufacturing and cooperative robotics. Data exchange over IEEE 802.11 networks may theoretically represent an appropriate solution for time–critical applications, provided that unreliability and non– determinism issues are properly handled. In this respect, this paper hence proposes an original solution, based on a cross– layer approach, to allow the realization of high–speed industrial control–over–Wi-Fi networked embedded systems. The proposal implements a novel robust frame–delay state estimator, a time efficient communication policy, and a specific tuning of critical protocol parameters. Suitable hardware–in–the–loop experiments have been carried out implemented exploiting two different embedded systems. Preliminary results show that the proposed architecture enables industrial control applications requiring a sampling rate of up to 1 kHz, even in presence of non negligible communication errors.

2019 24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2019

With the rise of Industry 4.0 and of the Industrial Internet, the computing and communication inf... more With the rise of Industry 4.0 and of the Industrial Internet, the computing and communication infrastructures achieved an essential role within process and factory automation, and cyberphysical systems in general. In this scenario, the OPC UA standard is currently becoming a widespread opportunity to enable interoperability among heterogeneous industrial systems. Nonetheless, OPC UA is characterized by a complex protocol architecture, that may impair the scalability of applications and may represent a bottleneck for its effective implementation in resource–constrained devices, such as low–cost industrial embedded systems. Several different OPC UA implementations are available, which in some significant cases are released under an open source license. In this context, the aim of this paper is to provide an assessment of the performance provided by some of these different OPC UA implementations, focusing specifically on potential development and resource bottlenecks. The analysis is carried out through an extensive experimental campaign explicitly targeting general purpose low–cost embedded systems. The final goal is to provide a comprehensive performance comparisons to allow devising some useful practical guidelines.

IEEE Transactions on Instrumentation and Measurement, 2021

The industrial Internet of Things (IIoT) paradigm represents an attractive opportunity for new ge... more The industrial Internet of Things (IIoT) paradigm represents an attractive opportunity for new generation measurement applications, which are increasingly based on efficient and reliable communication systems to allow the extensive availability of continuous data from instruments and/or sensors, thus enabling real-time measurement analysis. Nevertheless, different communication systems and heterogeneous sensors and acquisition systems may be found in an IIoT-enabled measurement application, so that solutions need to be defined to tackle the issue of seamless, effective, and low-latency interoperability. A significant and appropriate solution is the open platform communications (OPCs) unified architecture (UA) protocol, thanks to its object-oriented structure that allows a complete contextualization of the information. The intrinsic complexity of OPC UA, however, imposes meaningful performance assessment to evaluate its suitability in the aforementioned context. To this aim, this article presents the design of a general yet accurate and reproducible measurement setup that will be exploited to assess the performance of the main open-source implementations of OPC UA. The final goal of this work is to provide a characterization of the impact of this protocol stack in an IIoT-enabled measurement system, in particular, in terms of both the latency introduced in the measurement process and the power consumption.

2019 24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2019

Wireless networks are ever more deployed in industrial automation systems in various types of app... more Wireless networks are ever more deployed in industrial automation systems in various types of applications. A significant example in this context is represented by the transmission of safety data that, traditionally, was accomplished by wired systems. In this paper we propose an implementation of the Fail Safe over EtherCAT (FSoE) protocol on the top of IEEE 802.11 WLAN. The paper, after a general introduction of FSoE, focuses on the implementation of such protocol on commercial devices running UDP at the transport layer and connected via the IEEE 802.11 Wireless LAN. Then the paper presents some experimental setups and the tests that have been carried out on them. The obtained results are encouraging, since they show that good safety performance can be achieved even in the presence of wireless transmission media.

Con il presente lavoro si intende presentare un sistema per effettuare misure di emissione irradi... more Con il presente lavoro si intende presentare un sistema per effettuare misure di emissione irradiata ad alta frequenza (banda 2 \u2013 8 GHz) in precompliance, ovvero senza le restrizioni normative sul sito di prova. Questo sistema presenta delle caratteristiche molto interessanti di ripetibilit\ue0 della misura. Lo scopo del sistema proposto \ue8 di permettere al progettista che abbia gi\ue0 individuato le criticit\ue0 del proprio circuito in termini di emissioni irradiate, di effettuare in modo rapido ed economico delle misure di emissione per valutare l\u2019efficacia delle soluzioni adottate per la riduzione dei disturbi

2013 IEEE International Workshop on Applied Measurements for Power Systems (AMPS), 2013

ABSTRACT Measurement in power systems and, particularly, in smart grids and smart microgrids is o... more ABSTRACT Measurement in power systems and, particularly, in smart grids and smart microgrids is often concerned with harmonic analysis of voltage and current waveforms, which can be obtained by Fourier-based algorithms (e.g., phasor measurements, power quality analysis). Any such measurement algorithm is characterized by a fundamental time-frequency resolution tradeoff that relates the sampling frequency and the signal acquisition time. These well-known conditions determine basic limits of measuring equipment, for instance, when transient response times are considered. Phasor measurement reporting latency is also affected since, for any DFT-based algorithm, this time cannot be shorter than half the observation interval. This paper presents the application of an algorithm, based on the principles of compressive sensing (CS), that enhances frequency resolution by jointly processing multiple sets of DFT coefficients, computed from time-shifted acquisitions of the same waveform. By suitably merging such information, the CS algorithm can achieve an order-of-magnitude resolution improvement without significantly extending the total observation interval, since successive acquisitions can have a very large overlap. For harmonic analysis in power systems, this means accurate results can be obtained using shorter observation intervals, which allow to effectively track changes and reduce the effect of transients on measurements.

IEEE Transactions on Instrumentation and Measurement, 2014

Measurement in power systems and, particularly, in smart grids and smart microgrids is often conc... more Measurement in power systems and, particularly, in smart grids and smart microgrids is often concerned with harmonic analysis of voltage and current waveforms. The use of Fourier-based algorithms is widespread, and the limits following from the fundamental time-versus-frequency tradeoff that relates observation time to frequency resolution are well understood. This paper presents the application of an algorithm based on the principles of compressive sensing that can achieve an order-of-magnitude resolution improvement without significantly extending total observation time. For harmonic analysis in power systems, this means that accurate results can be obtained using shorter observation intervals, which allow to effectively track changes and reduce the effect of transients on measurements. The application of the algorithm to harmonics and interharmonics, as well as to phasor measurement, is considered and analyzed.

Wireless communication systems for industrial applications should cope with the demanding perform... more Wireless communication systems for industrial applications should cope with the demanding performance figures of real-time wired networks, providing high reliability and satisfying tight timeliness constraints. The implementation of a scheduling framework may represent a relevant method to deploy real-time behavior in distributed measurement, process control and supervision networks. A schedulability analysis, based on task parameters, determines if the network will be able to provide the guarantees required by the specified application. Nonetheless, this strategy and the related error recovery mechanism are often implemented at a high level protocol layer, without carefully considering the behavior of physical/data-link layers of the network. An effective characterization of the service time for packet delivery, as seen by the data link-layer, is instead required for a fine tuning of the scheduling algorithms. We analyzed the case of an IEEE 802.11g based network, where a central scheduler manages the traffic. We derived a model for the transmission times, in particular accounting for retransmissions due to channel impairment and interference. An improved model for the service time is then proposed, based on a cross-layer analysis. This allows to reshape the statistical knowledge of the metric, hence improving the network performance and admission test outcomes. The provided case-study enables the reader to understand the effectiveness of the proposed method, which provide a reliable soft real-time data acquisition system.

ABSTRACT The development of smart microgrids requires the adoption of distributed algorithms for ... more ABSTRACT The development of smart microgrids requires the adoption of distributed algorithms for energy management and control. In a microgrid, smart meters should also provide measuring functions similar to a PMU with comparable accuracy yet, being connected to a low-voltage distribution grid, they will have to cope with different electrical disturbances. This paper provides an accuracy analysis of known estimation techniques based on interpolated DFT (IpDFT) methods, under the impaired conditions of a low-voltage distribution grid. A brief discussion of expected impairments is provided first, then IpDFT is applied for the estimation of voltage phasors in the neighborhood of abrupt voltage amplitude variations. Results of experiments, run with the aid of an emulated power network, suitable data acquisition devices and signal processing, are presented and figures of merit concerning accuracy performance are discussed.

2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2020

The Industrial IoT scenario represents an interesting opportunity for distributed measurements sy... more The Industrial IoT scenario represents an interesting opportunity for distributed measurements systems, that are typically based on efficient and reliable communication systems, as well as the widespread availability of data from measurement instruments and/or sensors. The Open Platform Communications (OPC) Unified Architecture (UA) protocol is designed to ensure interoperability between heterogeneous sensors and acquisition systems, given its object–oriented structure allowing a complete contextualization of the information. Stemming from the intrinsic complexity of OPC UA, we designed an experimental measurement setup to carry out a meaningful performance assessment of its main open source implementations. The aim is to characterize the impact of the adoption of this protocol stack in a DMS in terms of both latency and power consumption, and to provide a general yet accurate and reproducible measurement setup.

IEEE Transactions on Industrial Informatics, 2020

In this article, we investigate an innovative solution, to implement high sampling frequency indu... more In this article, we investigate an innovative solution, to implement high sampling frequency industrial control by means of networked embedded systems connected via WiFi. The basic idea relies on a co-design approach for the control application, which is then able to adapt its sampling period, as well as to tune the Wi-Fi parameters, according to the feedback coming from the network. To this end, we implemented a cross-layer architecture acting at both application and data-link layers, which features a robust frame-delay state estimator, a time-efficient communication policy, and a specific tuning of the critical protocol parameters. Suitable hardware-in-the-loop experiments have been carried out exploiting two different embedded systems available off-the-shelf. The preliminary results, obtained from an extensive experimental campaign, are encouraging since they show that the proposed architecture enables industrial control applications requiring a sampling rate up to 1000 Hz, even in presence of communication impairments.

2019 18th European Control Conference (ECC), 2019

Wireless communication is a very appealing technology for industrial automation and networked con... more Wireless communication is a very appealing technology for industrial automation and networked control systems but much more unreliable as compared to wired solutions. Existing wireless standards for industrial automation such as ISA100 and WirelessHart address such unreliability but are limited to low control rates not exceeding 20 Hz, which are suitable for supervisory tasks, but not for high-bandwidth applications. In this work, we propose to use Wi-Fi, which thanks to its high data rates (> 300 Mbit/s), seems to be eligible for high performance applications requiring control rates greater than 1 kHz. Preliminary works mostly rely on emulation approaches, in which no change in the control design is needed, but the communication protocols have to be modified to enforce determinism (e.g. via TDMA-like protocols) at the price of longer delays. Conversely, this work follows a different paradigm, where the unreliability of the communication, due to random packet losses and delays, is coped by a robust model-based controller, which is capable of dealing with the stochastic nature of the communication channel while guaranteeing high control rates. The proposed approach has been tested on a hardware-in-the-loop laboratory setup involving conventional off-the-shelf Wi-Fi network interface cards, which showed how control rates in the order of 1 kHz are well within the possibility of Wi-Fi, even in the presence of substantial communication channel noise.

2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC)

The continuous evolution of additive manufacturing allows to produce innovative objects that are ... more The continuous evolution of additive manufacturing allows to produce innovative objects that are adopted in several diverse fields of applications. This trend can be further enhanced by the spreading of the Industrial Internet of Things (IIoT) paradigm which ensures effective interconnection among distributed, possibly heterogeneous, components and allows remote access by means of commercial devices such as PCs, tablets and smartphones. In this paper, we address a large additive manufacturing project which effectively exploits an IIoT architecture by embedding sensors (temperature, humidity, light, etc.) within the produced artifacts, so that they can make available diverse measurement data collected during both the production process (in real–time) and the subsequent lifetime of the artifacts, enabling further off–line analyses. This clearly represents an innovative and challenging feature that needs to be adequately investigated. To this regard, after describing the automation system of the project, we focus on the wireless system that implements the collection of measurements by the sensors within the artifacts. The design process led to the selection of a Low Power Wide Area Network, namely LoRaWAN, as a suitable communication solution. In this respect, we present here the tests performed to assess the actual feasibility and performance of such network in this specific application context. The obtained results are encouraging, since the sensors within the artifacts revealed able to exchange the required measurement data with the automation system in an effective way.

2020 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)

Wireless technologies play a key role in the Industrial Internet of Things (IIoT) scenario, for t... more Wireless technologies play a key role in the Industrial Internet of Things (IIoT) scenario, for the development of increasingly flexible and interconnected factory systems. Wi-Fi remains particularly attracting due to its pervasiveness and high achievable data rates. Furthermore, its Rate Adaptation (RA) capabilities make it suitable to the harsh industrial environments, provided that specifically designed RA algorithms are deployed. To this aim, this paper proposes to exploit Reinforcement Learning (RL) techniques to design an industry-specific RA algorithm. The RL is spreading in many fields since it allows to design intelligent systems by means of a stochastic discrete–time system based approach. In this work we propose to enhance the Robust Rate Adaptation Algorithm (RRAA) by means of a RL approach. The preliminary assessment of the designed RA algorithm is carried out through meaningful OMNeT++ simulations, that allow to recognize the beneficial impact of the introduction of RL with respect to several industry-specific performance indicators.

2020 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)

Modern industrial manufacturing plants, especially those using coordinated electrical drives with... more Modern industrial manufacturing plants, especially those using coordinated electrical drives with strict timing requirements, make extensive use of real-time communication networks. These systems, typically, are based on various topologies, include diverse protocols, and connect devices from different manufacturers, which may make them difficult to study, plan and optimize. As a solution, the adoption of digital twins allows to simulate such systems under various operating conditions in a low-cost and zero-risk environment. In this paper we address the digital twin of a networked electrical drive system, focusing on the real-time communication network used to connect the drives. In particular, we describe the simulation model of Profinet IO RT Class 1, implemented as an extension of the INET library of OMNeT++. Moreover, we present the outcomes of the tests carried out on a prototype simulated network and compare them with those of the equivalent real one.

2019 Design, Automation & Test in Europe Conference & Exhibition (DATE)

People affected by the Parkinson's disease are often subject to episodes of Freezing of Gait (FoG... more People affected by the Parkinson's disease are often subject to episodes of Freezing of Gait (FoG) near specific areas within their environment. In order to prevent such episodes, this paper presents a low-cost indoor localization system specifically designed to identify these critical areas. The final aim is to exploit the output of this system within a wearable device, to generate a rhythmic stimuli able to prevent the FoG when the person enters a risky area. The proposed localization system is based on a classification engine, which uses a fingerprinting phase for the initial training. It is then dynamically adjusted by exploiting a probabilistic graph model of the environment.

Ethernet POWERLINK (EPL) represents a prominent example of real-time Ethernet (RTE) communication... more Ethernet POWERLINK (EPL) represents a prominent example of real-time Ethernet (RTE) communication networks. It belongs to the IEC 61784 International Standard [1], where it is referred to as the Communication Pro\ua9le (CP) #1 within the CP Family #13

2017 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2017

In this work we aim at providing an initial analysis of the IEEE802.11s amendment that introduced... more In this work we aim at providing an initial analysis of the IEEE802.11s amendment that introduced support for mesh networking to Wireless LAN specifications. Indeed, there has been an increasing interest in the adoption of IEEE 802.11-based wireless systems also in the field of Distributed Measurement Systems (DMSs). Nonetheless, in such a scenario it is necessary to investigate the obtainable performance, in terms of latency, reliability and throughput. Toward this goal, we firstly considered the public available ns-3 IEEE 802.11s model, highlighting some details of the implemented design and also showing some of the unsupported features and open issues. Subsequently, we also leveraged on the mac80211 network emulation features embedded within the Linux kernel to test the mesh extensions included in Linux systems. Finally, using low-cost COTS hardware, exploiting the same mesh stack, we developed a real-world test bench allowing an experimental performance assessment. Results obtained from the presented setups are thus compared, and some open issues are finally discussed.

2020 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2020

In this paper we consider an Industrial Internet of Things (IIoT) system, based on the production... more In this paper we consider an Industrial Internet of Things (IIoT) system, based on the production of 3D–printed artifacts that are equipped with embedded sensors to monitor some environmental variables such as temperature, humidity, etc. These sensors allow to gather information during the production phase of the artifacts, as well as while they are deployed in their final locations, so that diverse operations (e.g. tuning of the production parameters, predictive maintenance, environmental monitoring) can be undertaken. Monitoring is implemented via LoRaWAN, a Low Power Wide Area Network (LPWAN) that allows to acquire data from the sensors embedded in the artifacts. After a description of the IIoT system, we provide the description of some experimental tests we carried out in this challenging context, aimed at investigating both the reliability of the transmission and the battery life time. The outcomes of such experiments indicate the actual feasibility of the proposed technique.

2019 IEEE 17th International Conference on Industrial Informatics (INDIN), 2019

Networked embedded systems for industrial control based on wireless support provide several advan... more Networked embedded systems for industrial control based on wireless support provide several advantages over wired counterparts, but often reveal unsuitable for the most demanding industrial control applications, such as advanced manufacturing and cooperative robotics. Data exchange over IEEE 802.11 networks may theoretically represent an appropriate solution for time–critical applications, provided that unreliability and non– determinism issues are properly handled. In this respect, this paper hence proposes an original solution, based on a cross– layer approach, to allow the realization of high–speed industrial control–over–Wi-Fi networked embedded systems. The proposal implements a novel robust frame–delay state estimator, a time efficient communication policy, and a specific tuning of critical protocol parameters. Suitable hardware–in–the–loop experiments have been carried out implemented exploiting two different embedded systems. Preliminary results show that the proposed architecture enables industrial control applications requiring a sampling rate of up to 1 kHz, even in presence of non negligible communication errors.

2019 24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2019

With the rise of Industry 4.0 and of the Industrial Internet, the computing and communication inf... more With the rise of Industry 4.0 and of the Industrial Internet, the computing and communication infrastructures achieved an essential role within process and factory automation, and cyberphysical systems in general. In this scenario, the OPC UA standard is currently becoming a widespread opportunity to enable interoperability among heterogeneous industrial systems. Nonetheless, OPC UA is characterized by a complex protocol architecture, that may impair the scalability of applications and may represent a bottleneck for its effective implementation in resource–constrained devices, such as low–cost industrial embedded systems. Several different OPC UA implementations are available, which in some significant cases are released under an open source license. In this context, the aim of this paper is to provide an assessment of the performance provided by some of these different OPC UA implementations, focusing specifically on potential development and resource bottlenecks. The analysis is carried out through an extensive experimental campaign explicitly targeting general purpose low–cost embedded systems. The final goal is to provide a comprehensive performance comparisons to allow devising some useful practical guidelines.

IEEE Transactions on Instrumentation and Measurement, 2021

The industrial Internet of Things (IIoT) paradigm represents an attractive opportunity for new ge... more The industrial Internet of Things (IIoT) paradigm represents an attractive opportunity for new generation measurement applications, which are increasingly based on efficient and reliable communication systems to allow the extensive availability of continuous data from instruments and/or sensors, thus enabling real-time measurement analysis. Nevertheless, different communication systems and heterogeneous sensors and acquisition systems may be found in an IIoT-enabled measurement application, so that solutions need to be defined to tackle the issue of seamless, effective, and low-latency interoperability. A significant and appropriate solution is the open platform communications (OPCs) unified architecture (UA) protocol, thanks to its object-oriented structure that allows a complete contextualization of the information. The intrinsic complexity of OPC UA, however, imposes meaningful performance assessment to evaluate its suitability in the aforementioned context. To this aim, this article presents the design of a general yet accurate and reproducible measurement setup that will be exploited to assess the performance of the main open-source implementations of OPC UA. The final goal of this work is to provide a characterization of the impact of this protocol stack in an IIoT-enabled measurement system, in particular, in terms of both the latency introduced in the measurement process and the power consumption.

2019 24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2019

Wireless networks are ever more deployed in industrial automation systems in various types of app... more Wireless networks are ever more deployed in industrial automation systems in various types of applications. A significant example in this context is represented by the transmission of safety data that, traditionally, was accomplished by wired systems. In this paper we propose an implementation of the Fail Safe over EtherCAT (FSoE) protocol on the top of IEEE 802.11 WLAN. The paper, after a general introduction of FSoE, focuses on the implementation of such protocol on commercial devices running UDP at the transport layer and connected via the IEEE 802.11 Wireless LAN. Then the paper presents some experimental setups and the tests that have been carried out on them. The obtained results are encouraging, since they show that good safety performance can be achieved even in the presence of wireless transmission media.

Con il presente lavoro si intende presentare un sistema per effettuare misure di emissione irradi... more Con il presente lavoro si intende presentare un sistema per effettuare misure di emissione irradiata ad alta frequenza (banda 2 \u2013 8 GHz) in precompliance, ovvero senza le restrizioni normative sul sito di prova. Questo sistema presenta delle caratteristiche molto interessanti di ripetibilit\ue0 della misura. Lo scopo del sistema proposto \ue8 di permettere al progettista che abbia gi\ue0 individuato le criticit\ue0 del proprio circuito in termini di emissioni irradiate, di effettuare in modo rapido ed economico delle misure di emissione per valutare l\u2019efficacia delle soluzioni adottate per la riduzione dei disturbi

2013 IEEE International Workshop on Applied Measurements for Power Systems (AMPS), 2013

ABSTRACT Measurement in power systems and, particularly, in smart grids and smart microgrids is o... more ABSTRACT Measurement in power systems and, particularly, in smart grids and smart microgrids is often concerned with harmonic analysis of voltage and current waveforms, which can be obtained by Fourier-based algorithms (e.g., phasor measurements, power quality analysis). Any such measurement algorithm is characterized by a fundamental time-frequency resolution tradeoff that relates the sampling frequency and the signal acquisition time. These well-known conditions determine basic limits of measuring equipment, for instance, when transient response times are considered. Phasor measurement reporting latency is also affected since, for any DFT-based algorithm, this time cannot be shorter than half the observation interval. This paper presents the application of an algorithm, based on the principles of compressive sensing (CS), that enhances frequency resolution by jointly processing multiple sets of DFT coefficients, computed from time-shifted acquisitions of the same waveform. By suitably merging such information, the CS algorithm can achieve an order-of-magnitude resolution improvement without significantly extending the total observation interval, since successive acquisitions can have a very large overlap. For harmonic analysis in power systems, this means accurate results can be obtained using shorter observation intervals, which allow to effectively track changes and reduce the effect of transients on measurements.

IEEE Transactions on Instrumentation and Measurement, 2014

Measurement in power systems and, particularly, in smart grids and smart microgrids is often conc... more Measurement in power systems and, particularly, in smart grids and smart microgrids is often concerned with harmonic analysis of voltage and current waveforms. The use of Fourier-based algorithms is widespread, and the limits following from the fundamental time-versus-frequency tradeoff that relates observation time to frequency resolution are well understood. This paper presents the application of an algorithm based on the principles of compressive sensing that can achieve an order-of-magnitude resolution improvement without significantly extending total observation time. For harmonic analysis in power systems, this means that accurate results can be obtained using shorter observation intervals, which allow to effectively track changes and reduce the effect of transients on measurements. The application of the algorithm to harmonics and interharmonics, as well as to phasor measurement, is considered and analyzed.

Wireless communication systems for industrial applications should cope with the demanding perform... more Wireless communication systems for industrial applications should cope with the demanding performance figures of real-time wired networks, providing high reliability and satisfying tight timeliness constraints. The implementation of a scheduling framework may represent a relevant method to deploy real-time behavior in distributed measurement, process control and supervision networks. A schedulability analysis, based on task parameters, determines if the network will be able to provide the guarantees required by the specified application. Nonetheless, this strategy and the related error recovery mechanism are often implemented at a high level protocol layer, without carefully considering the behavior of physical/data-link layers of the network. An effective characterization of the service time for packet delivery, as seen by the data link-layer, is instead required for a fine tuning of the scheduling algorithms. We analyzed the case of an IEEE 802.11g based network, where a central scheduler manages the traffic. We derived a model for the transmission times, in particular accounting for retransmissions due to channel impairment and interference. An improved model for the service time is then proposed, based on a cross-layer analysis. This allows to reshape the statistical knowledge of the metric, hence improving the network performance and admission test outcomes. The provided case-study enables the reader to understand the effectiveness of the proposed method, which provide a reliable soft real-time data acquisition system.

ABSTRACT The development of smart microgrids requires the adoption of distributed algorithms for ... more ABSTRACT The development of smart microgrids requires the adoption of distributed algorithms for energy management and control. In a microgrid, smart meters should also provide measuring functions similar to a PMU with comparable accuracy yet, being connected to a low-voltage distribution grid, they will have to cope with different electrical disturbances. This paper provides an accuracy analysis of known estimation techniques based on interpolated DFT (IpDFT) methods, under the impaired conditions of a low-voltage distribution grid. A brief discussion of expected impairments is provided first, then IpDFT is applied for the estimation of voltage phasors in the neighborhood of abrupt voltage amplitude variations. Results of experiments, run with the aid of an emulated power network, suitable data acquisition devices and signal processing, are presented and figures of merit concerning accuracy performance are discussed.