Multifunctional Control Research Articles

Multifunctional Control Strategy for a Hybrid Solid-State Transformer Applied to Modern Distribution Electric Grids

This paper presents the control and hardware design for a Hybrid Solid-State Transformer (HSST) applied to modern distribution systems. The HSST combines the advantages of conventional transformers, such as high efficiency and low cost, with those of Solid-State Transformers (SST), such as multifunctionality and fast dynamic response. Real-time simulation using a Typhoon HIL404 device is performed to validate the proposed multifunctional control strategy. The corresponding results validate the HSST’s capability to provide, while only processing partial system power, a regulated output voltage with grid voltage harmonic suppression and, at the same time, current load reactive and harmonic compensation to ensure a high-power factor and improved power quality to the grid.

Unravelling Influence Factors in Pattern Recognition Myoelectric Control Systems: The Impact of Limb Positions and Electrode Shifts.

Pattern recognition (PR)-based myoelectric control systems can naturally provide multifunctional and intuitive control of upper limb prostheses and restore lost limb function, but understanding their robustness remains an open scientific question. This study investigates how limb positions and electrode shifts-two factors that have been suggested to cause classification deterioration-affect classifiers' performance by quantifying changes in the class distribution using each factor as a class and computing the repeatability and modified separability indices. Ten intact-limb participants took part in the study. Linear discriminant analysis (LDA) was used as the classifier. The results confirmed previous studies that limb positions and electrode shifts deteriorate classification performance (14-21% decrease) with no difference between factors (p > 0.05). When considering limb positions and electrode shifts as classes, we could classify them with an accuracy of 96.13 ± 1.44% and 65.40 ± 8.23% for single and all motions, respectively. Testing on five amputees corroborated the above findings. We have demonstrated that each factor introduces changes in the feature space that are statistically new class instances. Thus, the feature space contains two statistically classifiable clusters when the same motion is collected in two different limb positions or electrode shifts. Our results are a step forward in understanding PR schemes' challenges for myoelectric control of prostheses and further validation needs be conducted on more amputee-related datasets.

Performance analysis of a new multifunctional aircraft environmental control system under variable operating conditions

Performance analysis of a new multifunctional aircraft environmental control system under variable operating conditions

Molecularization of Metasurfaces for Multifunctional Ultrafast All‐Optical Terahertz Waves

Hybrid metasurfaces incorporated by active materials hold great promise for state‐of‐the‐art terahertz functional devices. However, it is still a major challenge to achieve ultrafast, dynamic, and multifunctional effective control of THz waves via hybrid metasurfaces. Herein, a modulator consisting of split rings and cut‐wires is first demonstrated, with an amplitude of −35.6 dB at 0.524 THz. By embedding semiconductor silicon into specified locations to form a hybrid metasurface, the ultrastrong connectivity of the silicon bridges leads to rapid optical molecularization. Under photoexcitation, the frequency tuning range is 26.7%, the phase shifting reaches 357.5°, and the maximal modulation depth is 94.54%. Taking advantage of the rapid relaxation of photocarriers in the silicon bridges, the ultrafast frequency switching is within 1400 ps. More interestingly, by changing the positions of the silicon bridges, the frequency tuning range is further promoted to 60%, the phase shifting is 353.5°, the modulation depth of 100% is achieved, and the full recovery time is 1600 ps. Furthermore, the underlying mechanism of the ultrafast tuning process is elucidated. This work demonstrates the feasibility of all‐optical‐controlled hybrid metasurface to achieve multifunctional dynamic modulation of THz waves, which has tremendous potential for applications in optical switching, signal processing, and frequency conversion.

An Adaptive Multi-Functional Control Strategy for Power Management and Voltage-Frequency Regulation of PV, BESS, and Hybrid Units in a Microgrid

An Adaptive Multi-Functional Control Strategy for Power Management and Voltage-Frequency Regulation of PV, BESS, and Hybrid Units in a Microgrid

Switchable dual-functional optical vortex manipulation via cylindrical phase-change metagratings

Subwavelength artificial engineering microstructures, such as metasurfaces and metagratings, can realize superior optical properties that many natural materials cannot finish. However, most functionalities achieved are mostly single and fixed. The appearance of phase-change materials makes it possible to extend the functions of metagratings. Here, we propose and demonstrate a structural design of cylindrical phase-change metagratings based on VO2, which can achieve switchable dual-functional optical vortex manipulation in the terahertz range. Specifically, by excitation of the temperature-sensitive metallic and insulating states of VO2, the simple two-dimensional cylindrical gear-like structure can achieve dual-functionality for vortex waves with orbital angular momentum, namely efficient retroreflection and near-perfect absorption. In addition, we also discussed the influence of the gear-like structure dimensions on the transmissivity and absorptivity of dual-function vortex wave manipulation. This work provides a simple and effective approach for the tunable and multifunctional control of vortex waves in subwavelength artificial devices, with potential applications in automated device design and terahertz (THz) communications.

Swing-phase detection of locomotive mode transitions for smooth multi-functional robotic lower-limb prosthesis control.

Robotic lower-limb prostheses, with their actively powered joints, may significantly improve amputee users' mobility and enable them to obtain healthy-like gait in various modes of locomotion in daily life. However, timely recognition of the amputee users' locomotive mode and mode transition still remains a major challenge in robotic lower-limb prosthesis control. In the paper, the authors present a new multi-dimensional dynamic time warping (mDTW)-based intent recognizer to provide high-accuracy recognition of the locomotion mode/mode transition sufficiently early in the swing phase, such that the prosthesis' joint-level motion controller can operate in the correct locomotive mode and assist the user to complete the desired (and often power-demanding) motion in the stance phase. To support the intent recognizer development, the authors conducted a multi-modal gait data collection study to obtain the related sensor signal data in various modes of locomotion. The collected data were then segmented into individual cycles, generating the templates used in the mDTW classifier. Considering the large number of sensor signals available, we conducted feature selection to identify the most useful sensor signals as the input to the mDTW classifier. We also augmented the standard mDTW algorithm with a voting mechanism to make full use of the data generated from the multiple subjects. To validate the proposed intent recognizer, we characterized its performance using the data cumulated at different percentages of progression into the gait cycle (starting from the beginning of the swing phase). It was shown that the mDTW classifier was able to recognize three locomotive mode/mode transitions (walking, walking to stair climbing, and walking to stair descending) with 99.08% accuracy at 30% progression into the gait cycle, well before the stance phase starts. With its high performance, low computational load, and easy personalization (through individual template generation), the proposed mDTW intent recognizer may become a highly useful building block of a prosthesis control system to facilitate the robotic prostheses' real-world use among lower-limb amputees.

Multifunction Controlled 3D Printed Hand Prosthesis with the Myo Arm-Band by Hand Amputees

Upper limb amputations are highly impairing injuries that can substantially limit the quality of life of a person. The most advanced dexterous prosthetic hands have remarkable mechanical features. However, in most cases, the control systems are a simple extension of basic control protocols, making the use of the prosthesis not intuitive and sometimes complex. Furthermore, the cost of dexterous prosthetic hands is often prohibitive, especially for the pediatric population and developing countries. 3D-printed hand prostheses can represent an opportunity for the future. Open 3D models are increasingly being released, even for dexterous prostheses that are capable of moving each finger individually and actively rotating the thumb. However, the usage and testing of such devices by hand amputees (using electromyography and classification methods) is not well explored. This article aims to investigate the usage of a cost-effective system composed of a 3D-printed hand prosthesis and a low-cost myo electric armband. Two subjects with trans-radial amputation were asked to wear a custom-made socket supporting the Hand and the Thalmic Labs Myo armband. Afterward, the subjects were asked to control and use the prosthetic and to grasp several objects by attempting to perform a set of different hand gestures. Both the Hand and the Myo armband performed well during the test, which is encouraging considering that the Hand was developed as a research platform. The results are promising and show the feasibility of the multifunction control of dexterous 3D- printed hand prostheses based on low-cost setups. Factors such as the level of the amputation, neuromuscular fatigue, and mechanical limitations of the 3D-printed hand prosthesis can influence the performance of the setup. Practical aspects such as usability and robustness will need to be addressed for successful application in daily life.

A tunable terahertz metasurface with function of polarization conversion and circular dichroism

A tunable and multifunctional electromagnetic control metasurface is proposed. The metasurface comprises the graphene sheet and gold open ring, enabling multiband cross-polarization conversion (CPC) and line-to-circular polarization conversion (LTCPC). Simultaneously, it can achieve circular dichroism (CD) with amplitude of 0.99 at 2.28 THz, along with the capability for near-field imaging. The physical mechanism of operation is studied by analyzing surface current distribution and electric field. In addition, because the metasurface exhibits chiral characteristics, appropriate rotation can induce a phase gradient, facilitating a phase coverage of 0–360°. Based on the tunable phase gradient of metasurface, anomalous reflection and vortex beams can be realized.

Artificial intelligence motivated flexible single-electrode mode multilayer triboelectric sensor for smart mobility systems

Triboelectric tactile sensing technique is increasingly coming into people’s lives to bring convenience, so that there is an urgent necessity for this technique to be applied to smart mobility to increase safety and enhance the mobility experience. Herein, a single-electrode mode multilayer triboelectric sensor (MTS) motivated by artificial intelligence (AI) is proposed, which consists of styrene-butadiene-styrene (SBS)/ poly (vinylida-ene fluoride-trifluoroethylene) (PVDF-TrFE) nanofibers (NFs) film as the friction layer and substrate, laser-induced graphene (LIG)/molybdenum disulfide (MoS2) as the charge trapping layer, and Ag as the electrode. The MTS exhibits remarkable sensing performance, such as a wide response range of 5–100 N, 0.4–2 Hz multi-frequency response capability, and non-contact sensing, as well as distinguished self-powered performance. To demonstrate the practical significance of the proposed MTS, two applications are explored specifically after equipping with AI, including: (i) a smart in-vehicle system is constructed, which consists of unlocking section and multifunctional control with early warning section. (ii) a smart car control system is implemented, which can carry out special tasks instead of humans. These applications provide reliable ways to promote the development of human-machine interaction and smart mobility, as well as help to make lifestyles and mobility smarter, safer and more convenient.

Tailoring Sub‐Doppler Spectra of Thermal Atoms with a Dielectric Optical Metasurface Chip

AbstractCompact and robust structures to precisely control and acquire atomic spectra are increasingly important for the pursuit of widespread applications. Sub‐Doppler responses of thermal atoms are critical in constructing high‐precision devices and systems. In this study, a nanograting metasurface specifically is designed for atomic rubidium vapor and integrated it into a miniature vapor cell. Using the metasurface with built‐in multifunctional controls for light, pump‐probe atomic spectroscopy is established and sub‐Doppler responses are experimentally observed at low incident power. Moreover, the sub‐Doppler lineshape can be tailored by varying the incident polarization state. The spectrum transformation from absorption to transparency is observed. Using one of the sharp responses, laser stabilization with a stability of at 2 s can be achieved. This work reveals the effective control of atomic spectra with optical metasurface chips, which may have great potential for future developments in fundamental optics and novel optical applications.

Enhancing grid-connected inverter performance under non-ideal grid conditions: a multi-functional multiplexing control strategy

Compared to the traditional thermal power generation, new energy sources, such as wind and photovoltaic systems, are more vulnerable to the effects of non-ideal power grids due to their limited capacity. This susceptibility can jeopardize the safe operation of power equipment, degrade power output quality, and lead to non-compliance with grid-connected specifications. The LCL-type grid-connected inverter is a typical nonlinear system that weakens the controllability of the grid-connected energy. To address these challenges, this study employs feedback linearization theory to transform the inverter into a standard linear system. Subsequently, it utilizes linear system methodologies to develop robust control laws, ultimately introducing a multi-functional multiplexing control strategy for grid-connected inverters based on feedback linearization and Hamilton-Jacobi-Issacs inequality. Simulation results demonstrate that this multi-functional strategy outperforms traditional grid-connected inverter control schemes, effectively mitigating issues related to low short-circuit ratios, voltage fluctuations, imbalances, harmonics, and other non-ideal grid conditions. Furthermore, it significantly expands the system’s adaptability to varying weak grid impedances.

Miura origami based reconfigurable polarization converter for multifunctional control of electromagnetic waves

Polarization is one of the basic characteristics of electromagnetic (EM) waves, and its flexible control is very important in many practical applications. At present, most of the multifunction polarization metasurfaces are electrically tunable based on PIN and varactor diodes, which are easy to operate and have strong real-time performance. However, there are still some problems in them, such as few degrees of freedom of planar structure control, complex circuit, bulky sample, and high cost. In view of these shortcomings, this paper proposes a Miura origami based reconfigurable polarization conversion metasurface for multifunctional control of EM waves. The interaction between the electric dipoles is changed by adjusting the folding angle θ, thereby tuning the operating frequency of the polarization conversion and the polarization state of the reflected wave. This mechanical control method brings more degrees of freedom to manipulate EM waves. And the processed sample is with lightweight and low cost. To verify the performance of the proposed origami polarization converter, a Miura origami structure loaded with metal split rings is designed and fabricated. The operating frequency of the structure can be tuned in different folding states. In addition, by controlling the folding angle θ, linear-to-linear and linear-to-circular polarization converters can be realized at different folding states. The proposed Miura origami polarization conversion metasurface provides a new idea for reconfigurable linear polarization conversion and multifunctional devices.

Experimental Study on the Influence of Real-Time Temperature Cycling on Physical and Mechanical Properties of Granite

In this paper, a self-developed multi-functional high-temperature rock triaxial servo control testing machine was used to carry out uniaxial compression tests on the granite after the cooling and heating cycles under real-time temperature. The physical and mechanical properties of two types of granite damaged by hot and cold cycling under real-time temperature were discussed, and the changes in apparent color, longitudinal wave velocity, elastic modulus, uniaxial compressive strength, and damage characteristics of the specimen were revealed. The research results show the following: (1) With the increase in temperature or the increase in number of cycles, the uniaxial compressive strength, longitudinal wave velocity, and elastic modulus of the samples under the two cooling methods all show a decreasing trend, but the decrease in the range is different. The change range of the sample with temperature is greater than that with the number of cycles. (2) Under the dual action of real-time temperature and cold heat cycle damage, the failure form of granite is very random, but it is mainly shear failure, longitudinal splitting failure, and conical failure, and it is accompanied by a high temperature with the increase in the number of cycles, and the degree of crushing of the test piece gradually increases. For example, the sample under 600 °C water cooling for 25 cycles is crushed and destroyed. (3) As the temperature and the number of cycles increase, the surface of the water-cooled sample becomes rougher with the increase in the temperature and the number of cycles and the higher temperature, along with more cracks and debris; the increase in the temperature cycle, no obvious cracks appeared on the surface. The test results in this paper can provide relevant theoretical guidance for the stability and safety of rock in geothermal mining.

Magnetorheological fluid in prostheses: A state-of-the-art review

Magnetorheological fluids (MRF) are intelligent materials that can vary their yield stress in response to an applied magnetic field. This characteristic, combined with active and multifunctional control, allows the development of actuators with fast response time, low energy consumption, long service life, and reduced dimensions and weights. Various studies have been conducted to improve MR dampers in prosthetic applications, including knees, ankle-foot, hands, and sockets. Here, we present a critical review of the progress of MRFs in the prosthetic field. In addition, research in prostheses’ design, optimization, and control of magnetorheological actuators is investigated, along with MRF modeling, mode of operation, type of MR actuator, classification, and working principle of MRF-based devices. Although MRFs are considered promising materials for designing novel prosthetic devices, this review shows that applications have been predominantly focused on lower limb prostheses. We conclude by discussing possible future applications and challenges that must be faced to enable and improve commercial applications based on MRF technology.

Functioning algorithm of the electronic on-board distributed system for automation control of a city electric bus

The issue of automation control for peripheral devices of a city electric bus is considered. A functioning algorithm for an electronic on-board distributed system for automation control, which allows constant monitoring of the vehicle operation, is made. A hardware implementation of this algorithm by using multifunctional controllers is proposed. The developed automation system makes it possible to increase the electrical equipment control efficiency of public electric transport. Keywords electric bus, automation, algorithm, block diagram, on-board system, dashboard, programmable controller

PoroFluidics: deterministic fluid control in porous microfluidics.

Microfluidic devices with open lattice structures, equivalent to a type of porous media, allow for the manipulation of fluid transport processes while having distinct structural, mechanical, and thermal properties. However, a fundamental understanding of the design principles for the solid structure in order to achieve consistent and desired flow patterns remains a challenge, preventing its further development and wider applications. Here, through quantitative and mechanistic analyses of the behavior of multi-phase phenomena that involve gas-liquid-solid interfaces, we present a design framework for microfluidic devices containing porous architectures (referred to as poroFluidics) for deterministic control of multi-phase fluid transport processes. We show that the essential properties of the fluids and solid, including viscosity, interfacial tension, wettability, as well as solid manufacture resolution, can be incorporated into the design to achieve consistent flow in porous media, where the desired spatial and temporal fluid invasion sequence can be realized. Experiments and numerical simulations reveal that different preferential flow pathways can be controlled by solid geometry, flow conditions, or fluid/solid properties. Our design framework enables precise, multifunctional, and dynamic control of multi-phase transport within engineered porous media.

Centralized Multifunctional Control of Integrated Electricity–Gas Network in District Energy System Considering Resilience

District energy systems (DESs) and integrated electricity-gas systems (IEGSs) are closely related. The performance of these systems under critical situations, such as faults and equipment outages, has not been adequately investigated. The operation of DESs may also be significantly affected by installing central generating systems for gas or electricity sectors. These central generating units may deal with outages and faults. In the literature, there is not a comprehensive model that considers renewables in IEGS, uncertainties of generating systems, mutual connection between electricity and gas sub-grids, ability of exchanging power with upstream grid, centralized storage device for electrical sector, and centralized power supply for gas sector. All these points are considered and modeled in the proposed model. This paper presents several multi-purpose control strategies for DES that are designed and implemented on an IEGS. Electricity and thermal loads are used to model the DES energy needs. In the electricity subsystem, by using several local renewable energy sources (RESs) and a central battery, not only the electric loads are supplied, but also the DES can be connected to the upstream grid and trade the scheduled power in accordance with the electricity market contract in all normal and critical conditions. On the other hand, the gas subsystem is powered by a central fuel cell. Gas and electricity subsystems in the DES region are designed to assist each other during outages and events in order to increase the resilience. All RESs, central battery, and fuel cell are equipped with individual controllers to achieve the above objectives. A centralized control framework is used to manage all these controllers under a variety of operating conditions. Numerical simulations in MATLAB software verify the model ability to control DES and IEGS properly.

Multifunctional metasurface for Terahertz wavefront manipulation based on the combination of vanadium dioxide and graphene

In this paper, we propose a multifunctional wavefront control metasurface based on vanadium dioxide (VO2) and graphene. The unit cell structure contains a VO2 substrate, three rectangular metal strips as the bottom layer, orthogonal graphene strips as the top layer, and an intermediate layer consisting of a split ring resonator and circular metal patches. The desired performances can be achieved by changing the parameters of the split ring resonator in the middle layer, as well as controlling the phase transition state of VO2 and the Fermi level of graphene. When VO2 is in the insulating phase and the Fermi level of graphene is 1 eV, a transmissive metasurface is established, which realizes cross-polarization conversion, anomalous refraction, focusing lens, and orbital angular momentum generation at the frequency of 0.63 THz by changing the geometric sizes of the unit cell. When VO2 is in the metal phase and the Fermi level of graphene is 0.01 eV, a reflective metasurface can be achieved, which realizes terahertz beam splitting, radar cross section, and anomalous reflection of a single beam at the frequency of 0.63 THz. This multifunctional wavefront control metasurface treating the combination of VO2 and graphene exhibits significant application prospects in terahertz transmission, imaging, and communication.

Advanced Compensation Methods for Isolated Unsymmetrical Three-Phase Multiple Microgrids Employing Energy Storage System (ESS)

The integration of unbalanced loads into three-phase microgrids (MGs) will be the emphasis of this study. The power quality difficulties that arise when the point of common coupling (PCC) is reached, will be the primary concern of this investigation. A few of these issues include unbalanced power flow, voltage, and the sharing of reactive power in an unbalanced manner. An energy storage system (ESS) that makes use of innovative control algorithms is used to correct the imbalances that occur in island multi-microgrids (MMGs). The reactive power generated by the MMG is balanced by the ESS’s two types of control approaches, modified reverse droop control and multifunction control. The active and reactive power references needed by the ESS are likewise produced by these control methods. The proposed control algorithms ensure that PV inverters of varying ratings have optimal load power distribution, hence minimizing power imbalances and PCC voltage in the MMG. The MATLAB/SIMULINK application may be used to do an analysis on the outcomes of the simulation.