Slave Units Research Articles

The KM3NeT Broadcast optical system network

The optical data transport system of the KM3NeT neutrino telescope at the bottom of the Mediterranean Sea will serve more than 6000 optical modules in the detector arrays with a point-to-point optical connection to the control stations onshore. The ARCA and ORCA detectors of KM3NeT are being installed at a depth of about 3500 m and 2500 m, respectively and their distance to the control stations is about 100 km and 40 km. The two detectors are optimised for the detection of cosmic neutrinos with energies above about 1 TeV (ARCA) and of atmospheric neutrinos with energies in the range 1 GeV– 1 TeV (ORCA). The expected maximum data rate is 200 Mbps per optical module. The implemented optical data transport system matches the layouts of the networks of electro-optical cables and junction boxes in the deep sea. For efficient use of the fibres in the system the technology of Dense Wavelength Division Multiplexing is applied. To comply with the scientific goals of KM3NeT, a time calibration of 1 ns between the many optical modules in the detector arrays is essential for the reconstruction of the neutrino events. For the first time in a deep sea neutrino telescope the White Rabbit protocol over Ethernet is used for the clock distribution. Downstream slow control and base module signals are broadcasted to all optical modules in the detector array. Synchronisation is achieved by communication between a White Rabbit master onshore and a White Rabbit slave unit inside the optical modules. In this contribution the KM3NeT broadcast optical data transport system is presented.

SECOND ORDER SLIDING MODE CONTROL FOR ISLANDED AC MICROGRIDS WITH RENEWABLE POWER RESOURCES

Microgrids have attracted a lot of attention and are the future power systems. This paper proposes a new control scheme for islanded AC microgrid (MG) using master-slave technique. Stability and high performance are vital for islanded MG. Two second order sliding mode controls (SMCs) are designed in stationary reference frame for master and slave units to control the voltage and powers respectively. Both designed controls guarantee the convergence of considered outputs to their reference values. The proposed controls are robust, simple, chattering free and only need local measurements. The control method proposed in this paper can be easily extended to microgrids with any number of slave units and parallel connected inverters. The effectiveness of the proposed control scheme is verified through simulation results in SIMULINK/MATLAB environment and compared to feedback linearization control and a modified conventional SMC.

Adaptive walking control for quadruped robot by using oscillation patterns.

To improve the adaptability of quadruped robot in multiple scenarios, an adaptive locomotive system based on the double-layered central pattern generator (CPG) is proposed. The novel CPG network consists of double master units and subsets of slave units based on gyroscope signals including yaw and pitch angle. The response of master units provides the ability to control the 1st joins of quadruped robot, while slave units can generate the symmetry signals to control the 2nd and 3rd joints. The CPG network enables the seamless switching of locomotion gaits to stops and starts by using an ultrasonic sensor. Through adjusting the mutually dependent parameters, joints can generate the joint angles to achieve steering behavior. For adaptive movement on an irregular surface, stable ranges of the robot body yaw and pitch angles are proposed by using gyroscope signals. The experimental results verify that the quadruped robot with the proposed double-layered CPG network can perform stable trot pattern in a complex environment.

A Novel State-of-Charge-Based Droop Control for Battery Energy Storage Systems to Support Coordinated Operation of DC Microgrids

A modern dc microgrid often comprises renewable energy sources (RESs), such as photovoltaic (PV) generation units, battery energy storage systems (BESSs), and local load, and it is also connected to the utility grid through a point of common coupling (PCC). While most existing approaches have to rely on communication links to achieve the desired control performance, this article proposes a novel control strategy without resorting to the communication links. This is achieved by assigning BESSs as master units and regulating the dc bus voltage with a novel state-of-charge (SoC)-based droop control, where the BESSs coordinate the slave units (e.g., RES and utility grid) with the aid of the dc bus signaling (DBS) technique to avoid overcharging and overdischarging of these BESSs. In the proposed droop control, the reference voltage for these BESSs is designed for coordinated operation between BESSs and utility grid, and it is maintained constant in the normal SoC range, which can reduce dc voltage variation. Droop coefficients designed for SoC balance of BESSs are dynamically adjusted based on their own SoC values. Furthermore, the preset maximum deviation between the reference voltage and the dc bus voltage ensures the reliable coordinated operation. Real-time hardware-in-loop (HIL) tests considering three different scenarios are conducted to validate the effectiveness of the proposed method.

Analysis of Steady State Availability of a Series– Parallel Repairable System with Hot Standbys, Three Units and Vacation

Abstract: In this paper we analyze the steady state availability of a series-parallel repairable system. In this system, the first unit is master control unit and other two are slave units and one single repairman who operates single vacation. Under that assumption each unit has arbitrary repair time distribution & a constant failure rate. Also, it is noted that to calculate the availability of the system it is required to obtain the explicit expression and for obtaining steady-state probabilities it is necessary to use “the supplementary variable” method as well as “Markov process theory”.

Application of Improved Robot-assisted Laparoscopic Telesurgery with 5G Technology in Urology

The demand for telesurgery is rising rapidly, but robust evidence regarding the feasibility of its application in urology is still rare. From March to October 2021, a surgeon-controlled surgical robot in a tertiary hospital in Qingdao was used to remotely conduct robot-assisted laparoscopic radical nephrectomy (RN) in 29 patients located in eight primary hospitals. The median round-trip delay was 26 ms (interquartile range [IQR] 5) and the median distance between the primary hospital and the surgeon was 187 km (IQR 57). Both the master unit and the slave unit were guaranteed by network and mechanical engineers, and surgical assistants were well prepared on the patient side to prevent complications. The primary evaluation metric was the success rate, defined as the percentage of patients who underwent successful remote RN without conversion to other surgical procedures and no major intraoperative or postoperative complications. The results demonstrate that the combination of 5G technology and surgical robots is a novel potential telemedicine-based therapy choice for renal tumors. Patient summaryOur study shows that telesurgery using 5G technology is a safe and feasible treatment option for patients with kidney tumors. The total delay between the remote location and the operating rooms where surgery was being performed was just 200 ms. This approach could reduce health care costs and improve the quality of medical services accessed by patients.

Raspberry Pi based Smart Classroom Architecture with Local Network

Classrooms are important building blocks of a school campus. Therefore, a feasible architecture for building and running smart classrooms is essential. Today all online education system is based on the browser/server structure or client/server structure and for this system required the computer to every student. As the number of student increases cost of education also increases. In small schools and institutes could not able to afford a computer to every student. Instead, we aim to design an embedded device with only one master computer and number of slave units. Raspberry Pi has the capability of being configured as an access point and as a web server, so it can be used for creating applications reachable from mobile devices without needing an Internet connection. The proposal is based on the possibility for students to Answer questionnaires from their mobile devices. The teacher can observe answers in real time. This solution adds dynamism integrating the existing mobile devices in the classroom. It eliminates the use of computers or laptops to each student which reduces size and cost of the project. Programming language used in this project would be HTML alongwith Python, Operating System will be Raspbian and Questionnaire Software will be Node-Red. This paper explains the proposal features in terms of used hardware and software, as well as the functional tests performed and their implementation allowing replication.

Hybrid SiC-Si DC–AC Topology: SHEPWM Si-IGBT Master Unit Handling High Power Integrated With Partial-Power SiC-MOSFET Slave Unit Improving Performance

Based on partial power conversion concept, this article proposes a hybrid silicon carbide (SiC)-silicon (Si) dc–ac topology to improve performance in high power application. First, master unit (MU) uses Si-IGBT working in low frequency to handle main high power because of its high rated current capacity and high switching loss, whereas the low power quality of MU is induced by the low switching frequency. And SiC-MOSFET suffers from high cost and high conduction loss at high power level. To solve these problems, the partial-power slave unit (SU) based on SiC-MOSFET is connected with MU in series through line-frequency transformer, whereas SU works in high frequency to compensate the harmonic of MU and adjusts the total output voltage. In this new topology, the corresponding hybrid modulation strategy and multiple quasi-proportional-resonance control for single-phase system are introduced in detail to ensure the reliable operation. In the end, a 4.5-kW converter prototype was implemented and tested. Simulation and experiment results are given to verify the performance of the proposed hybrid dc–ac topology.

A Cfd Thermal Analysis and Optimization Design of a Bms Slave Unit for Application in Electric Vehicles

A Cfd Thermal Analysis and Optimization Design of a Bms Slave Unit for Application in Electric Vehicles

The Ariel Instrument Control Unit

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey mission (Tinetti 2019; Puig et al. 2018; Pascale et al. 2018), has been selected in March 2018 by ESA for the fourth medium-class mission (M4) launch opportunity of the Cosmic Vision Program, with an expected lift off in late 2028. It is the first mission dedicated to measuring the chemical composition and thermal structures of the atmospheres of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of our own Solar System. Its Payload (P/L) (Eccleston and Tinetti 2018; Eccleston et al. 2017; Middleton et al. 2019), has been designed to perform transit spectroscopy from space during primary and secondary planetary eclipses in order to achieve a large unbiased survey concerning the nature of exoplanets atmospheres and their interiors, to determine the key factors affecting the formation and evolution of planetary systems (Tinetti et al. 2017, 2018). Ariel will observe hundreds of warm and hot transiting gas giants, Neptunes and super-Earths around a wide range of host star types, targeting planets hotter than $\sim $ 600 K to take advantage of their well-mixed atmospheres. It will exploit primary and secondary transit spectroscopy in the 1.10 to 7.80 μm spectral range and broad-band photometry in the optical (0.50 - 0.80 μm) and Near IR (0.80 - 1.10 μm) . One of the two instruments of the Ariel Payload is the Fine Guidance System (FGS), including three photometric channels (two used for guiding as well as science) between 0.5-1.1 μm plus a low resolution NIR spectrometer for 1.1-1.95 μm range. Along with FGS an IR Spectrometer (AIRS) (Amiaux et al. 2017) is foreseen, providing low-resolution spectroscopy in two IR channels: Channel 0 (CH0) for the 1.95 − 3.90 μm band and Channel 1 (CH1) for the 3.90 − 7.80 μm range. Finally, an Active Cooler System (ACS) including a Ne Joule-Thomson cooler is adopted to provide active cooling capability to the AIRS detectors working at cryogenic temperatures. AIRS is located at the intermediate focal plane of the telescope and common optical system and it hosts two HgCdTe-based hybrid IR detectors and two cold front-end electronics (CFEE) for detectors control and readout. Each CFEE is driven by a Detector Control Unit (DCU) part of AIRS but hosted within and managed by the Instrument Control Unit (ICU) of the Payload (Focardi et al. 2018). ICU is a warm unit residing into the S/C Service Module (SVM) and it is based on a cold redundant configuration involving the Power Supply Unit (PSU) and the Commanding and Data Processing Unit (CDPU) boards; both DCUs are instead cross-strapped and can be managed by the nominal or the redundant (PSU+CDPU) chain. ICU is in charge of AIRS management, collecting scientific and housekeeping (HK) telemetries from the spectrometer and HK from the telescope (temperatures readings), the P/L Optical Bench (OB) and other Subsystems (SS), thanks to a warm slave unit (TCU, Telescope Control Unit) interfaced to the ICU. Science and HK telemetries are then forwarded to the S/C, for temporary storage, before sending them to Ground. Here we describe the status of the ICU design at the end of B1 Phase, prior to the Mission Adoption Review (MAR) by ESA, with some still open architectural choices to be addressed and finalised once selected the ICU industrial Prime contractor.

A Novel Hybrid-HHOPSO Algorithm Based Optimal Compensators of Four-Layer Cascaded Control for a New Structurally Modified AC Microgrid

This paper proposes a new modified architecture for AC microgrid consisting of multiple grid-supporting master units (MUs) and multiple grid-feeding slave units (SUs). In this study, a coordinated four-layer hierarchal control (HC) approach is applied to the proposed structure for allowing the MUs, SUs and loads to be easily integrated as a microgrid and operated in both grid-integrated and standalone operation mode. The proposed structure of the AC microgrid enhances the system redundancy to prevent the single point of failure of MU and has more stability, efficiency, flexibility and reliability than the conventional structures. Furthermore, optimal design guidelines, based on a new hybrid Harries hawks and particle swarm optimization algorithm (H-HHOPSO) with the cooperation of different types of proposed multi-objective functions, are presented to fulfill the study objectives. The optimization constraints/objectives are employed for optimal parameters selection of HC controllers to improve the power quality, enhance dynamic and steady-state performance and guarantee a seamless transition between operation modes. To accomplish this work, the newly modified structure is modeled, constructed in MATLAB/SIMULINK and tested under the variations of generations and loads. This structure is also examined when the fault occurs at any one of the MUs and during the connecting and disconnecting of utility grid. This testing is to verify its flexibility and reliability, and confirm the effectiveness and robustness of the proposed optimal controllers. Additionally, the experimental work is carried out using the hardware-in-the-loop real-time emulation to prove the optimal controllers' feasibility. Finally, the experimental and simulation results are compared.

Idleness as a micro ethico-political action

According to Deleuze and Guattari, the central project of capitalism consists in the articulation of economic production with the production of subjectivity. The first part of this paper expands on how capitalism manufactures a particular mode of existence corresponding to its economic flows. Herein, it is argued that the paradigmatic figure of our neoliberal and machinic times is a self-condemning subject, attached simultaneously to the assemblages of capitalism as slave units in the cybernetic sense. The second part revolves around the question of activating a new process of subjectivation towards a new mode of existence. It is argued that the latter requires a voyage to an immanent outside and returning to the present plane of existence with new perspectives to recombine its elements differently. This spiritual voyage presupposes a suspension of the general mobilisation decreed by capital. In this context, idleness – in the form of meditative life – is offered as a micro ethico-political action that may not only allow us to acknowledge our habitually reactive selves but also give access to the outside where hitherto unknown existential refrains and configurations could be discovered.

Multiple Synchronized Inertial Measurement Unit Sensor Boards Platform for Activity Monitoring

The synchronization between wireless sensor nodes is a big issue in all those low-cost systems in which each node performs measurements using its own sensors and stores the measured values locally. In the absence of synchronization, it is impossible to relate all the measurements coming from the different sub-systems on a single time scale for the extraction of complex features. The importance of this issue is even bigger when the sensors' sampling rate is high as for the Inertial Measurement Unit platforms. The paper addresses the issue of managing a large multi-sensor platform for off-line activities with a reduced sensor node complexity and guaranteeing the perfect synchronization for each acquired sample. The new simple and light algorithm proposed overcomes the limits of the commonly used protocols and it is suitable for this kind of applications. The entire system consists of an Android smartphone, a master unit and several slave units. Each board has a 9 Degrees of Freedom (DoF) Inertial Measurement Unit, a micro-SD for data storage and an ARM® Cortex ™-M4 CPU SoC supporting the protocols for both Bluetooth Low Energy (BLE) 5 and 2.4 GHz custom communications.

Robust control of a multi-bus DC microgrid based on adaptive Lyapunov function method

Due to the development of power electronic devices, the DC microgrids are competing AC microgrids, and even in some areas, such as efficiency, reliability, stability, DC microgrids are superior. In spite of mentioned advantages, the main technical challenge related to operation of the DC microgrids is to provide a fast and stable voltage regulation. In this paper, a robust control structure is proposed for multi-bus DC microgrids. Adopting master–slave control strategy, an adaptive voltage control scheme is proposed to robustly maintain the master unit voltage at the nominal value. In addition, an adaptive current controller is designed to robustly regulate the current of all the DG units in the grid-connected mode, as well as the slave units in the islanded mode of operation. All of the controllers are designed based on local measurements and are independent with respect to parameters, dynamic, and topology of the DCMG loads. The control scheme is shown to be stable and robust subject to parametric uncertainties and various types of disturbances. The consistent and effectiveness of the proposed control scheme is demonstrated through simulation studies in MATLAB® software environment.

Master Slave Topology for Parallel Operation of Renewable Energy based Distributed Generator

This paper presents an effective control methodology to integrate multiple photovoltaic (PV) based distributed generator (DG) in microgrid. In general, the multiple PV based DG will operate in parallel and the rating of each PV unit is defined by the rating of the corresponding DC-DC converter. Each PV units operates independently with respective to the controller of the dc-dc converter and feeds power to the common bus. In this paper, a master slave control methodology is proposed to integrate multiple PV units with a single maximum power point tracking (MPPT) controller. In the proposed master slave approach, one PV unit is considered as master unit which is controlled through MPPT algorithm and voltage control method. Other PV units are considered as slave units and operate with current control without MPPT control. Compared with the traditional methods available in the literature, the proposed methodology reduces the complexity and controller cost of the parallel operation of multiple PV based DG system. Simulation and experimental results verify its feasibility.

Battery management system implementation with the passive control method using MOSFET as a load

In this study, a battery management system was implemented using the passive charge balancing method. The battery system was created with lithium ion battery cells commonly used in electric vehicles. Two main microprocessors were used as a master and slave for the management system. An STM32f103C8 microcontroller was used as a master, and a PIC18f4520 microcontroller was used as slave control units in the battery management system. Charge control of a battery pack consisting of four cells was performed. The information received from the current and voltage sensors was collected from each cell using a slave controller and sent smoothly to the master controller system. These experimental results indicated that the passive balancing method was implemented and the battery cells were charged successfully. The proposed method was applied to battery pack consisting of a four-cell LiFePO4 battery with a capacity of 40 Ah. This work incorporated original situation that have not been realized before. A digital to analog converter circuit was created using a buck converter topology. Thus, the MOSFET was used as an adjustable resistance. Also, it was one of the first studies in which the MOSFET was used as a regulated resistor in battery management systems.

Intelligent Control of Microgrid With Virtual Inertia Using Recurrent Probabilistic Wavelet Fuzzy Neural Network

A microgrid with virtual inertia using master-slave control is proposed in this article to overcome the drawbacks of traditional inverter-based distributed generators for lack of inertia and without grid-forming capability. The microgrid using master-slave control is composed of a storage system, a photovoltaic (PV) system and a varying resistive three-phase load. The storage system and PV system are regarded as the master unit and the slave unit, respectively, in the microgrid. Moreover, in order to improve the reactive power control in grid-connected mode and the transient response of microgrid during the switching between the grid-connected mode and islanding mode, an online trained recurrent probabilistic wavelet fuzzy neural network (RPWFNN) is proposed to replace the conventional proportional-integral (PI) controller in the storage system. Furthermore, when the microgrid is operated in islanding mode, the load variation will have serious influence on the voltage control of the microgrid. Thus, the RPWFNN control is also proposed to improve the transient and steady-state responses of voltage control in the microgrid. Finally, according to some experimental results, excellent control performance of the microgrid with virtual inertia using the proposed intelligent controller can be achieved.

A selective harmonic compensation and power control approach exploiting distributed electronic converters in microgrids

This paper proposes an approach to obtain harmonic compensation and power control by exploiting the electronic power converters deployed in low-voltage microgrids. By the proposed approach, distributed harmonic current compensation is achieved without interfering with the converter’s power exchange involved in interfacing the local energy resources (e.g., renewable sources, storage devices) with the grid. The control framework refers to a master/slave microgrid architecture where distributed power converters play as slave units, coordinated by a centralized controller; the data exchange among agents occurs periodically, concerns current magnitudes only, and can be fulfilled by communication means of limited performance. The paper shows the achievable results in terms of power quality improvements and discusses the challenges related with the aimed objective. The proposed methodology is evaluated by means of simulation and experimental tests on a single-phase low-voltage microgrid prototype comprising nonlinear loads and two converters. Different cases of generation limits, load variations, voltage levels, voltage distortions, and line parameters are considered in the tests reported. In addition, the robustness of the proposed method to non-ideal and faulty communication links is discussed and shown by means of experimental results.

Frequency superimposed robust coordinated control in a hybrid microgrid

The paper presents a frequency superimposed robust coordinated control technique for the precise power bifurcation among the multiple energy storage elements. In the proposed control principle, a dynamically computed low voltage virtual frequency is injected into the dc control network. According to the total power demand, and the energy density of the battery units, the virtual frequency is computed in the master controller units. Further, with respect to the measured virtual frequency and their specified drooping gain, the slave units interact. In consequence of the conditional drooping factors, the slave units can locally decide their spell of execution. Thus, the proposed scheme ensures a precise power management among the multiple energy storage elements without introducing any virtual resistance in the dc network. In an addition, accounting the system stability, the proposed scheme controls the amount of ac grid interference into the dc microgrid. Considering two numbers of battery as master controllers and a compressed air storage as a slave unit, the performance and the stability are evaluated and found to be satisfactory.

Accurate GPS-based timestamp facility for Gran Sasso National Laboratory

A new system to assign accurate timestamps to events recorded by experiments running underground has been designed, installed and tested at INFN Gran Sasso National Laboratory, Italy. This facility is based on a Master unit installed on surface and receiving time information from a GPS receiver, and Slave units placed underground which get data packet from the Master via optical fiber and assign the timestamps. The system is able to provide a time accuracy of 15 ns (1σ) and precise reference frequencies to the experiments. It is now part of the infrastructure of the Laboratory for all the experimental activities which need accurate timestamps.