Switching Control Research Articles

Stable Levitation of Single-point Levitation Systems for Maglev Trains by Improved Cascade Control

The stable levitation of single-point levitation systems for electromagnetic suspension (EMS) maglev trains, which belongs to the control task of nonlinear and unstable systems, is investigated in this paper. Considering the simplicity and convenience of the control application, we dedicate ourselves to combining and applying common control methods to achieve the stable levitation rather than designing complex controls or using advanced control methods. For this goal, the single-point levitation system is divided into an electromagnetic system and a motion system first. On this basis, we design the Lyapunov controller and sliding mode controller as Controller I, while another Lyapunov controller and the standard Proportional Integral Derivative (PID) controller are designed as Controller II, which are used to control the electromagnetic system and motion system respectively and constitute the improved cascade control to achieve the stable levitation. Furthermore, the switching controller consisting of the standard PID controller and the designed Lyapunov controller is used as Controller II for the improvement of both stability and robustness.

Laser-induced CdS/TiO2/graphene dual photoanodes for ratiometric self-powered photoelectrochemical sensor: an innovative approach for aflatoxin B1 detection.

A ratiometric self-powered photoelectrochemical sensor based on laser direct writing technology was constructed to address the problem that the conventional single-signal detection mode was susceptible to the influence of instrumentation and environmental factors, which interfered with the detection results. Laser-induced CdS/TiO2/Graphene was prepared as dual photoanodes (PA1 and PA2), which were controlled by multiplexed switches to form a photocatalytic fuel cell with Pt cathode. By modifying the aptamer of aflatoxin B1 (AFB1) on the photoanode surface, the target was specifically captured to the electrode surface to form a biological complex, which increased the steric hindrance and affected the electron transfer, thus reducing the output signal of the sensor. Targets with different concentrations were incubated on the surface of PA1, and targets with fixed concentrations were incubated on the surface of PA2. Under the control of the multiplex switch, the output signals of the two photoanodes were recorded, and the ratio of these two signals was used as the basis for the quantitative detection of AFB1. The sensor output was linearly increasing with the logarithm of AFB1 concentration from 1.0 to 150ngmL-1 and the detection limit was 0.0974ngmL-1. Additionally, this method had good stability, fast response, and good selectivity to real samples, providing an effective method for food safety monitoring.

Spectral period doubling and encoding of dissipative optical solitons via gain control

Period-doubling bifurcation, as an intermediate state between order and chaos, is ubiquitous in all disciplines of nonlinear science. However, previous experimental observations of period doubling in ultrafast fiber lasers are mainly restricted to self-sustained steady state, controllable manipulation and dynamic switching between period doubling and other intriguing dynamical states are still largely unexplored. Here, we propose to expand the vision of dissipative soliton periodic doubling, which we illustrate experimentally by reporting original spontaneous, collisional, and controllable spectral period doubling in a polarization-maintaining ultrafast fiber laser. Specifically, the spontaneous period doubling can be observed in both single- and double-pulses. The mechanism of the switchable state and periodic doubling was revealed by numerical simulation. Moreover, state transformation of individual solitons can be resolved during the collision of triple solitons involving stationary, oscillating, and period doubling. Further, controllable deterministic switching between period doubling and other dynamical states, as well as exemplifying the application of period-doubling-based digital encoding, is achieved under programmable pump modulation. Our results open a new window for unveiling complex Hopf bifurcation in dissipative systems and bring useful insights into nonlinear science and applications.

Adaptive switching control of full state constrained nonlinear systems with unknown control directions

AbstractIn this article, an adaptive switching controller is designed for the stabilization control and the tracking control of nonlinear systems suffering from full state constraints, unknown control directions, and system uncertainties. Featured with changing signs and unbounded increasing magnitudes, a switching control structure is proposed to deal with the unknown control direction problem. In order to explore and finally fix the correct control direction, an adaptive switching rule, a switching function, and a reference function are constructed. An integral Lyapunov function is adopted for the design of the control law, which ensures that full state constraints will not be violated. Using this method, the nonlinear system can be properly controlled without extra estimations or approximations. The boundedness of all the states and the stability of the system are analyzed and guaranteed. Finally, simulations are conducted to validate the proposed method, and the results illustrate its effectiveness.

Phytic acid-based super antifreeze multifunctional conductive hydrogel for human motion monitoring and energy harvesting devices

Conductive hydrogels have broad application prospects in the field of self-powered sensors and energy harvesting devices due to their good electrical conductivity and flexibility. However, at low temperatures, conductive hydrogels are usually frozen, resulting in problems such as poor electrical conductivity and flexibility, which seriously hinder the application of these fields. To address these challenges, phytic acid (PA) was employed as the crosslinker and antifreezing agent in this study. Polyvinyl alcohol (PVA), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), chitosan (CS), and PA were used as raw materials to successfully synthesize PVA/AMPS/CS/PA (PACP) multifunctional conductive hydrogels with outstanding antifreeze and water retention properties (freezing point below −80 °C, 30-day water loss rate of 3.5%). In addition, PACP hydrogels exhibit exceptional electrical conductivity of up to 9.4 S/m, along with antibacterial and biocompatible properties, enabling their utilization as wearable sensors on human skin tissue. Notably, the PACP hydrogel-based triboelectric nanogenerator (PACP-TENG) excels in accurately monitoring human motion and powering small electronic devices, facilitating remote control of small light switches. The resulting open circuit voltage is as high as 314 V at 25 °C and about 110 V at low temperature. Therefore, PACP hydrogels with excellent properties are expected to expand their applications in these fields.

A coordination control between energy storage based DVR and wind turbine for continuous fault ride‐through

AbstractContinuous fault ride‐through (CFRT) issues often arise in wind power systems. CFRT results in continuous voltage fluctuations which is characterized by “initially decreasing and then increasing” and can significantly disrupt the normal operation of wind power systems. To mitigate CFRT related problems, one approach is the utilization of energy storage (ES) based dynamic voltage restorers (DVRs). Nevertheless, the prohibitive costs and substantial ES requirements hamper practical implementation. In this article, a control scheme incorporating adaptive mode switching and coordinated control is proposed. First, the adaptive mode switching control leverages the advantages of two DVR compensation methods to reduce the injected voltage amplitude. The mode switching is activated by the DC link voltage and utilizes the PQR transformation to unlock the phase‐locked loop (PLL). Subsequently, an adaptive coordination coefficient is introduced, which considers the margin of ES regulation power and rotor inertia, to maintain power balance during CFRT. This proposed control strategy not only enables wind turbines to seamlessly ride through continuous faults without disconnecting from the grid but also leads to a reduction in the ES compensation requirement. To validate the effectiveness of the proposed approach, simulations based on Simulink and hardware‐in‐loop (HIL) experiments are conducted.

Controller switching with the anti-bump adapter

Switching on a new or retuned controller while keeping the control loop engaged tends to generate transient “bumps” in the commands and plant outputs. For a linear time-invariant (LTI) controller in state–space form, these bumps can be mitigated or even suppressed by resetting the controller state to an appropriate non-zero value adapted to the pre-switching trajectories of the feedback loop signals. This paper proposes a simple way to compute this adapted controller state by minimizing the difference between the commands actually applied immediately before switching and the virtual command trajectory which the new controller would have generated if it had been activated in parallel. This adapted state can be recursively computed as the output of an LTI system in standard state–space form, the anti-bump adapter. Computing the anti-bump adapter involves only standard matrix algebra and control concepts (e.g., observability and controllability matrices/Gramians). Calculations are very simple and can be translated into compact computer code. This bump suppression procedure is applicable to any discrete-time or continuous-time LTI SISO or MIMO controller, without any assumption on or knowledge of either the previously active controller or the plant. Illustrative applications to continuous-time and discrete-time switching problems and a Matlab® code for computing the anti-bump adapter are presented.

Bumpless transfer control for switched time-delay systems with application to aero-engine control

For switched time-delay systems, the bumpless transfer control issue is investigated by utilizing the multiple piecewise Lyapunov–Krasovskii function approach. First, a time-delay-dependent bumpless transfer concept is put forward to depict the transient performance of switched time-delay systems, which restricts the bumps in the amplitude of the present state and the time-delay state, simultaneously. Second, a state-dependent switching signal with a prescribed time is designed to avoid switching frequently. A time-varying switching controller is developed to decrease control bumps. Third, under the premise of achieving asymptotic stability, a solvability condition ensuring a satisfactory bumpless transfer performance is derived through relaxing the traditional bumpless transfer condition. Finally, an instance of the aero-engine control system is used for exhibiting the validity of the presented method.

Concomitant Observer-Based Multi-Level Fault-Tolerant Control for Near-Space Vehicles with New Type Dissimilar Redundant Actuation System

This paper presents a concomitant observer-based multi-level fault-tolerant control (FTC) for near-space vehicles (NSVs) with a new type dissimilar redundant actuation system (NT-DRAS). When NSV flight control system faults occur in NT-DRAS and attitude-corresponding sensors, the NSV hybrid output states, including the concomitant observer usable states and the real system states, are applied to solve the FTC gain by using the linear quadratic regulator (LQR) technique. Furthermore, since NT-DRAS is used in NSVs, a multi-level (actuation system level and flight control level) FTC strategy integrating NT-DRAS channel switching and flight control LQR is proposed for complex and worsening fault cases. The most important finding is that though the proposed strategy is applicable for worsening fault cases in NSVs, systematic and accurate criteria for the process being performed are necessary and can improve the FTC efficiency with minimal FTC resources. Additionally, such criteria can improve the NSV’s responsiveness to comprehensive faults, provided that the real-time performance of the fault detection and diagnosis (FDD) scheme can be further optimized. The concomitant observer convergence and the multi-level FTC strategy have been verified by numerical simulations based on the Matlab/Simulink platform.

Visual Target Interaction Modeling with Multichannel Data Fusion

Facing the demand for accurate, fast, and natural human–computer interaction in the multi-screen control environment, the traditional exchange method of frequent switching control of multi-screen through mouse, keyboard, and other manual methods has problems of low efficiency, weak flexibility, and poor experience. In this paper, we research multi-screen precision control technology based on eye movement to break through the difficulties of precise recognition of human vision under complex environments and poor stability of vision estimation under frequent switching control of multi-screen. This study explores the technology for controlling multiple screens with high precision by tracking eye movements. It overcomes the challenges associated with reliably discerning human visual focus in intricate settings and the instability of visual assessments during rapid transitions between multiple screens. The experimental results of 1143 eye-movement capture tasks are studied, including the accurate recognition technology of human head posture and pupil gaze direction under complex backgrounds, illumination, and different visual field environments, and the theoretical modeling method of multi-screen precise target interaction based on eye-movement is explored. The expression data will be processed using convolutional neural networks, and the dataset will be trained through Python programming and tested on test samples collected by simulated flight crews in the laboratory with an accuracy rate of more than 85%.

Fine inductive VAR control with high power quality using thyristor controlled reactors and discontinuous phase control switching in power systems

The thyristor-controlled reactors (TCR) are widely employed to regulate the power system voltage and improve stability. However, TCR injects higher-order harmonics in the line current. For instance, in conventional TCR configurations, the total harmonic distortion (THD) is 78.5% at 10% of the fundamental current, and even it is 10% at 80% of the fundamental current. A previously reported control approach uses two reactors with a half-wave control design, which was only effective for the upper half of the control range. This paper proposes four new circuit configurations for reactive power regulation using discontinuous phase control (DPC). The new reactor design is also proposed for high-density magnetic flux perform well with double windings and three-inductor setups under the proposed approach. The proposed configuration of a multistage reactor with varying magnitudes provides extremely low total harmonic distortion (THD) across a near-complete control range. Even, the proposed design has achieved virtually zero THD for the reactor current. For THD to be less than 10%, a specific reactor pair is switched such that the control is only in the top half of the control range. The following configuration is based on reactors with the same magnitude. Like integral cycle control, the on-off control is employed for coarse action, whereas phase control is applied for fine control. All the proposed configurations are practically realized, and the performance is experimentally verified satisfactorily.

Analysis of Indoor Air Quality and Fresh Air Energy Consumption Based on Students’ Learning Efficiency under Different Ventilation Methods by Modelica

This paper aimed to explore a suitable ventilation method at a lower cost of energy to pursue a high learning efficiency based on the characteristics of a Chinese student group and campus building. Firstly, the model was established by Modelica and a good agreement between the numerical simulation and the results by CONTAM 3.4.0.3 was obtained. Secondly, the effects of the fixed window-opening ratio method (FWM), switch control window-opening ratio method (SCM), and automatic control window-opening ratio method (ACM) on CO2 concentration, indoor air temperature, and the heating capacity of air conditioning were investigated. The results showed that, when the FWM with 0% opening or 20% opening was adopted, the indoor CO2 concentration (ICC) was higher than the limit value of the classroom air quality standard, which was 1000 ppm. When the fixed window-opening ratio was greater than 40%, the indoor air temperature could not be controlled at the set value of 18 °C, which presented bad indoor thermal comfort. Meanwhile, when the ACM was adopted, the duration to meet good indoor thermal comfort was 57.17% higher than that of the SCM. However, both of them could maintain the average ICC below the set value in the class. Lastly, the fresh air energy consumption under different ventilation methods was compared. When the design temperature was 13.5 °C, it could be revealed that the fresh air energy consumption under the ACM, SCM, and FWM with 40% opening was 46.58%, 48.38%, and 51.26% lower than those at 18 °C. In summary, it was recommended to set the design temperature of the classroom at 13.5 °C, and the ACM was suggested as a suitable ventilation method to provide fresh air for the classroom.

NIR-II light-activated and Cu nanocatalyst-enabled bioorthogonal reaction in living systems for efficient tumor therapy

Bioorthogonal reaction refers to chemical reactions that occur within a biological system without interfering the normal biochemical process, offering the unprecedented versatility in engineering chemical reactions within cells. However, the precise regulation of bioorthogonal reaction in living systems is mired by the complexity of the physiological environment and the toxicity of catalysts. Herein, considering the deeper tissue penetration and reduced phototoxicity compared to visible light and ultraviolet, a second near infrared (NIR-II) light-activated Cu-based bioorthogonal reaction is developed to achieve precise spatiotemporal control and effective switching for Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) mediated chemical transformations in tumor, reducing the off-target effects. The catalytic activity of Cu catalyst through valence state interconversion between Cu(II) and Cu(I) can be precisely regulated in a reversible manner under NIR-II light irradiation-induced photoelectron transfer, which controls the extent of desired drug synthesis in bioorthogonal reaction. Meanwhile, the adverse effects of Cu(I) can be substantially mitigated within normal tissues due to their oxygen-rich condition. By utilizing NIR-II light and oxygen level, the Cu bioorthogonal catalyst achieves a balance between catalytic activity and biocompatibility. The ability to achieve precise spatiotemporal control and reversible catalysis makes this NIR-II light-mediated CuAAC platform an efficient and adaptable tool for bioorthogonal chemistry in living systems.

DBT is a metabolic switch for maintenance of proteostasis under proteasomal impairment

Proteotoxic stress impairs cellular homeostasis and underlies the pathogenesis of many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). The proteasomal and autophagic degradation of proteins are two major pathways for protein quality control in the cell. Here, we report a genome-wide CRISPR screen uncovering a major regulator of cytotoxicity resulting from the inhibition of the proteasome. Dihydrolipoamide branched chain transacylase E2 (DBT) was found to be a robust suppressor, the loss of which protects against proteasome inhibition-associated cell death through promoting clearance of ubiquitinated proteins. Loss of DBT altered the metabolic and energetic status of the cell and resulted in activation of autophagy in an AMP-activated protein kinase (AMPK)-dependent mechanism in the presence of proteasomal inhibition. Loss of DBT protected against proteotoxicity induced by ALS-linked mutant TDP-43 in Drosophila and mammalian neurons. DBT is upregulated in the tissues of ALS patients. These results demonstrate that DBT is a master switch in the metabolic control of protein quality control with implications in neurodegenerative diseases.

DBT is a metabolic switch for maintenance of proteostasis under proteasomal impairment.

Proteotoxic stress impairs cellular homeostasis and underlies the pathogenesis of many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). The proteasomal and autophagic degradation of proteins are two major pathways for protein quality control in the cell. Here, we report a genome-wide CRISPR screen uncovering a major regulator of cytotoxicity resulting from the inhibition of the proteasome. Dihydrolipoamide branched chain transacylase E2 (DBT) was found to be a robust suppressor, the loss of which protects against proteasome inhibition-associated cell death through promoting clearance of ubiquitinated proteins. Loss of DBT altered the metabolic and energetic status of the cell and resulted in activation of autophagy in an AMP-activated protein kinase (AMPK)-dependent mechanism in the presence of proteasomal inhibition. Loss of DBT protected against proteotoxicity induced by ALS-linked mutant TDP-43 in Drosophila and mammalian neurons. DBT is upregulated in the tissues of ALS patients. These results demonstrate that DBT is a master switch in the metabolic control of protein quality control with implications in neurodegenerative diseases.

Intrinsically safe DAB converter for reliable power supply in harsh environment via extended phase shift pulse train control

AbstractIn this article, an extended‐phase‐shift‐based pulse train control (EPS‐PT) for an intrinsically safe dual active bridge (DAB) converter is proposed to satisfy the safe and reliable power supply in harsh environments such as gas stations, chemical plants, and mining tunnels in complex power systems. A discrete pulse switching control method is introduced, and the input voltage and output current are sampled to calculate the primary target phase shift angle of the DAB converter, followed by the inner phase shift angle, while the secondary phase shift angle is rapidly adjusted by the voltage feedback. In order to meet the requirements of effective control and safe power supply in harsh environments, the system parameters are designed by comprehensively considering the control performance and intrinsically safe requirements. The simulation and experimental results demonstrate that the proposed DAB converter exhibits rapid dynamic response and intrinsic operation safety.

A Zero‐Voltage Switching Three‐Level Nonisolated Bidirectional DC/DC Converter With a Lossless Passive Component Auxiliary Circuit and Design‐Oriented Analysis

ABSTRACTA three‐level bidirectional buck/boost converter (TLBBBC) is suitable for power electronic systems with a high‐voltage DC link for its switches with half voltage. In order to achieve higher efficiency, a novel zero‐voltage switching (ZVS) TLBBBC is proposed in this paper to enable operation with higher switching frequencies. In the proposed ZVS TLBBBC, two identical ZVS cells, each composed of a resonant inductor, two snubber capacitors, and two resonant capacitors, are integrated with the conventional three‐level (TL) topology to enable soft switching in all four switches in both buck and boost modes. Here, one advantage is that soft‐switching conditions are ensured under conventional control methods without using the auxiliary switch or complex control methods. In addition, the soft‐switching region is derived, clearly illustrating the relationship between the duty cycle ratio and the power inductor current that ensures the soft‐switching condition. Hence, the soft‐switching region is beneficial for assisting in ZVS cell design and guiding the converter in running in ZVS. Then, the operation and design considerations of the proposed topology are analyzed in detail. Finally, the experimental results of an 800‐W prototype for both the boost and buck modes are presented to confirm the theoretical analysis.

Innovative Geotechnical Solutions for Sustainable Infrastructure Development

Aim: To examine innovative geotechnical solutions for sustainable infrastructure development. Problem Statement: The advancement in the world urbanization together with high rise in global population has alarmed the need for new infrastructures with additional innovative research to be conducted with already existing assets. Thus, It is important that geotechnical engineering should include basic practices targeting resource-efficient and environment-friendly techniques in order to add to sustainable development. Significance of Study: This technical review critically examines the innovative geotechnical solutions for sustainable infrastructure development. The content presented in this manuscript will be beneficial to professionals in the area of geotechnical engineering. Methodology: Recent relevant published articles in the area of innovative geotechnical solutions for sustainable infrastructure development were consulted. These include journal articles, conference papers, Asian Development Bank articles and unpublished doctoral documents. Discussion: The six main environmental objectives of the Taxonomy Regulation to ensure the contours of an environmentally sustainable infrastructure were stated to include: (1) sustainable protection and use of marine and water resources (2) pollution control and prevention (3) switch to a circular economy (4) mitigation of climate change (5) restoration and protection of ecosystems and biodiversity and (6) adaptation of climate change. The three phase methods for sustainability infrastructure development in geotechnics were critically discussed. An imaginary excavation site in the municipality of Rozzano was referenced as a case study to reveal the application of the proposed methodology to the soil treatment systems. It was noticed that the adoption of an LCA introduces additional deep knowledge and the required quantitative analysis for sizing the assessment. Conclusion: The examined innovative geotechnical solutions were contributory to sustainable infrastructure development.

Variable Structure Controller for Energy Savings in an Underwater Sensor Platform.

This paper introduces a new variable structure controller designed for depth control of an autonomous underwater sensor platform equipped with a variable buoyancy module. To that end, the prototype linear model is presented, and a finite element-based method is used to estimate one of its parameters, the hull deformation due to pressure. To manage potential internal disturbances like hull deformation or external disturbances like weight changes, a disturbance observer is developed. An analysis of the observer steady-state estimation error in relation to input disturbances and system parameter uncertainties is developed. The locations of the observer poles according to its parameters are also identified. The variable structure controller is developed, keeping energy savings in mind. The proposed controller engages when system dynamics are unfavorable, causing the vehicle to deviate from the desired reference, and disengages when dynamics are favorable, guiding the vehicle toward the target reference. A detailed analysis determines the necessary switching control actions to ensure the system reaches the desired reference. Finally, simulations are run to compare the proposed controller's performance with that of PID-based controllers recently developed in the literature, assessing dynamic response and energy consumption under various operating conditions. Both the VBM- and propeller-actuated vehicles were evaluated. The results demonstrate that the proposed controller achieves an average energy consumption reduction of 22% compared to the next most efficient PID-based controller for the VBM-actuated vehicle, though with some impact on control performance.

The value of error-correcting responses for cognitive assessment in games

Traditional conflict-based cognitive assessment tools are highly behaviorally restrictive, which prevents them from capturing the dynamic nature of human cognition, such as the tendency to make error-correcting responses. The cognitive game Tunnel Runner measures interference control, response inhibition, and response-rule switching in a less restrictive manner than traditional cognitive assessment tools by giving players movement control after an initial response and encouraging error-correcting responses. Nevertheless, error-correcting responses remain unused due to a limited understanding of what they measure and how to use them. To facilitate the use of error-correcting responses to measure and understand human cognition, we developed theoretically-grounded measures of error-correcting responses in Tunnel Runner and assessed whether they reflected the same cognitive functions measured via initial responses. Furthermore, we evaluated the measurement potential of error-correcting responses. We found that initial and error-correcting responses similarly reflected players’ response inhibition and interference control, but not their response-rule switching. Furthermore, combining the two response types increased the reliability of interference control and response inhibition measurements. Lastly, error-correcting responses showed the potential to measure response inhibition on their own. Our results pave the way toward understanding and using post-decision change of mind data for cognitive measurement and other research and application contexts.