Digital Control Research Articles

A 64 × 128 3D-Stacked SPAD Image Sensor for Low-Light Imaging.

Low-light imaging capabilities are in urgent demand in many fields, such as security surveillance, night-time autonomous driving, wilderness rescue, and environmental monitoring. The excellent performance of SPAD devices gives them significant potential for applications in low-light imaging. This article presents a 64 (rows) × 128 (columns) SPAD image sensor designed for low-light imaging. The chip utilizes a three-dimensional stacking architecture and microlens technology, combined with compact gated pixel circuits designed with thick-gate MOS transistors, which further enhance the SPAD's photosensitivity. The configurable digital control circuit allows for the adjustment of exposure time, enabling the sensor to adapt to different lighting conditions. The chip exhibits very low dark noise levels, with an average DCR of 41.5 cps at 2.4 V excess bias voltage. Additionally, it employs a denoising algorithm specifically developed for the SPAD image sensor, achieving two-dimensional grayscale imaging under 6 × 10-4 lux illumination conditions, demonstrating excellent low-light imaging capabilities. The chip designed in this paper fully leverages the performance advantages of SPAD image sensors and holds promise for applications in various fields requiring low-light imaging capabilities.

Study on the quality of reproduction of graphical linear micro-images using electrophotographic printing

Today’s market of visual graphic communication includes many various advertising, publishing and packaging products printed on different materials. Many products are printed using conventional printing technologies such as offset printing or flexography, in addition to digital ones like Electrophotography and Ink Jet. The graphic images on prints often contain extremely fine graphic details, such as micro-lines or micro-text elements, which are part of various identification, security markings, codes, etc. It is a very important task to optimally model these micro-images on printed graphic communication products at the design stage, in order to ensure their brightness, legibility and geometric dimensions meet the requirements, not only immediately after printing, but also, for example, after a certain period during the life cycle of the printed product after exposure to the sunlight spectrum, or to other mechanical or environmental effects. This paper presents a methodology and results for the assessment of the quality of the reproduction of fine image details, i.e. the micro-lines of different widths arranged on the print in different directions. A specially developed original digital press quality control wedge with monochromatic micro-lines, microtext and screen dots bars of CMYK colours was applied to assess the accuracy of micro-image reproduction. In this part of the study, the wedge fields with positive micro-lines arranged in different directions individually and in groups were analysed. The width of the micro-lines was measured under the microscope to assess the accuracy of the dimensional reproduction and the deviations from the nominal value. To assess the influence of different parameters of the system “printing press-paper-inks” on the reproduction of image microelements, the prints for this part of the study were printed using electrophotographic printing techniques on different dry-toner printing presses on different types of paper. The width and deviations of the micro-lines on the print were measured along the print direction, perpendicular and at 45˚ to the print direction. Measurements of the reproduction accuracy of monochrome micro-line images, printed on dry-toner electrophotographic presses, showed that the accuracy of micro-line reproduction depends not only on the printing system, its resolution and the characteristics of the paper, but also on the direction of the positioning of the micro-lines on the printed sheet. The obtained results allow us to compare the capability of digital printing systems to reproduce linear micro-images on visual graphic communication products of any size and geometric orientation, to select optimal systems for printing specific products, and to model the layout of micro-images on products at the design stage, by assessing the orientation of the micro-images on the printed sheet.

Adaptive Fault-Tolerant Tracking Control for Discrete-Time Nonstrict-Feedback Nonlinear Systems With Stochastic Noises

This paper discusses the problem of fault-tolerant tracking control for discrete-time nonstrict-feedback nonlinear systems in the presence of stochastic noises and actuator faults. The system is characterized by a discrete-time nonstrict-feedback structure and multiplicative stochastic noise related to the states, which poses a challenge for the design and analysis of the fault-tolerant controller. Moreover, the considered actuator faults include multiplicative and additive faults without prior information. By integrating the properties of the backstepping framework and neural networks, and by introducing an adaptive fault compensation term, a novel fault-tolerant tracking control strategy is proposed. The effects of faults are compensated and the difficulties caused by the system structure are overcome, avoiding the algebraic loop problem and overcoming the causal contradiction. Given specific parameters, the designed fault-tolerant controller can ensure that the tracking error converges to an adjustable region regarding the origin and that all system signals are uniformly bounded concerning the mean-square sense. The simulation examples illustrate the effectiveness of the designed fault-tolerant control method. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —As system complexity has been increasing, practical systems are often affected by faults when performing tracking control. Fault-tolerant control can provide acceptable robustness and improve system safety. On the one hand, many practical systems are nonlinear, difficult to model mathematically and accurately, and affected by stochastic noises. On the other hand, with digital control, the object is a discrete-time system. In practical applications, the upper bounds of the faults and the noises are often unknown. In this paper, a novel adaptive fault-tolerant control method is proposed for the more general uncertain discrete-time nonlinear systems, i.e., nonstrict-feedback nonlinear systems, with stochastic noises and actuator faults. Neural networks and an adaptive fault compensation term are integrated into the fault-tolerant controller. By adjusting the controller parameters properly, it is ensured that the tracking error converges to a small neighborhood of zero in the event of a fault occurring. In future research, sensor faults, input constraints, optimal control design, and applications in multi-agent systems will be considered.

CRITERIA FOR THE OPTIMAL MODE OF NON-DESTRUCTIVE TESTING BY DIGITAL RADIOGRAPHY

Theoretically justified and experimentally confirmed criteria for the selection of modes and parameters of digital radiography control. The analysis of the digital image quality showed its dependence on the parameters and control modes, on the value of the signal-to-noise ratio. Analytical information was obtained a relationship linking the size of the defect in the plane perpendicular to the axis of the radiation beam, the size of the focal spot of the radiation source, the parameters of the control circuit and the pixel size of the detector system. The validity of the analytical expression has been confirmed experimentally.

Self-guided digital behavioural therapy versus active control for fibromyalgia (PROSPER-FM): a phase 3, multicentre, randomised controlled trial

International guidelines have recommended cognitive behavioural therapy, including acceptance and commitment therapy (ACT), as it offers validated benefits for managing fibromyalgia; however, it is inaccessible to most patients. We aimed to evaluate the effect of a 12-week, self-guided, smartphone-delivered digital ACT programme on fibromyalgia management. In the PROSPER-FM randomised clinical trial conducted at 25 US community sites, adult participants aged 22-75 years with fibromyalgia were recruited and randomly assigned (1:1) to the digital ACT group or an active control group that offered daily symptom tracking and monitoring and access to health-related and fibromyalgia-related educational materials. Randomisation was done with a web-based system in permuted blocks of four at the site level. We used a blind-to-hypothesis approach in which participants were informed they would be randomly assigned to one of two potentially effective therapies under evaluation. Research staff were not masked to group allocation, with the exception of a masked statistics group while preparing statistical programming for the interim analysis. The primary endpoint was patient global impression of change (PGIC) response rate at week 12. Analyses were by intention to treat. The trial was registered with ClinicalTrials.gov, NCT05243511 (now fully closed). Between Feb 8, 2022, and Feb 2, 2023, 590 individuals were screened, of whom 275 (257 women and 18 men) were randomly assigned to the digital ACT group (n=140) and the active control group (n=135). At 12 weeks, 99 (71%) of 140 ACT participants reported improvement on PGIC versus 30 (22%) of 135 active control participants, corresponding to a difference in proportions of 48·4% (95% CI 37·9-58·9; p<0·0001). No device-related safety events were reported. Digital ACT was safe and efficacious compared with digital symptom tracking in managing fibromyalgia in adult patients. Swing Therapeutics.

Robust digital voltage mode control of buck converter with enhanced tracking performance

The digital voltage controller of power converters is used because it has many advantages over its analog counterparts. Thus, in this paper, a controller of digital voltage mode is designed and analyzed for a non-isolated DC-DC buck converter in continuous conduction mode (CCM). First, an analog controller is designed using a Bode plot to achieve the desired stability margins in the frequency domain. Next, the analog controller is discretized using bilinear transformation with the pre-warping method. The characteristics of the discretized compensator can be maintained close to the corresponding analog compensator as long as a proper sampling time is selected. The digital control scheme is simulated with a nonlinear DC-DC buck converter model in MATLAB/Simulink to investigate the controller performance. The simulation results demonstrated the validation of the proposed digital voltage-mode control design approach. The developed digital controller eliminates DC error by tracking the reference voltage, achieving a fast transient response, maintaining specified stability margins, and effectively rejecting large disturbances.

Design and Implementation of Silicon-Doped Ferrogate Stacking JL-VTFET in MIC Sepic Convertor

This paper introduces a Ferro technique in the junctionless vertical tunnel field effect transistor in which the ferroelectric property in the [Formula: see text] is developed with the help of Silicon doping in it. The incorporation of the ferroelectric oxide stacking with [Formula: see text] results in low sub-threshold slope and high trans-conductance which is highly suitable for sensing of small voltage and converting it into strong drain current. The introduction of the high k-dielectric material with [Formula: see text] also leads to small lattice mismatch so that the losses can be reduced. The device shows ON current in the order of (2.62 × 10[Formula: see text]A/[Formula: see text]m) and the ratio of the ON to OFF drain current is noted as (of 2.031 × 10[Formula: see text]). Moreover, the device exhibits sub-threshold slope 35mV/dec and the ratio of trans-conductance to drain current (gm/[Formula: see text]) in the range of 150–350 V[Formula: see text]. Then the design structure is used to develop the circuit of multiple input converters (MIC) because the device shows high conversion rate (trans-conductance). For the converter, State-space analysis is used for the modeling of converter which was further followed with the design of converters’ energy storing apparatus with its voltage gain formulation. Interaction analysis is used to create a decentralized controller. The controllers’ robustness is tested using parametric uncertainty. A 175-watt experimental archetype with 36 volt and 24-volt sources is developed in the lab. The digital controller was implemented using the processor. The efficacy of controllers for regulating sources and loads has been verified. The controller’s strength is ensured by the satisfactory correlation between simulation and investigational results. For the result outcome one can validate Silicon Doped Ferro Gate Stacking JL-VTFET results for low power applications.

Simplified 1.5 μm Distributed Feedback Semiconductor Laser (DFB-LD) Frequency Stabilization System Based on Gas Absorption Chamber

The classical 1.5 μm band frequency-stabilized laser using acetylene gas saturated absorption can achieve high frequency stability and reproducibility, but its system design is complex and bulky. For some practical applications, a simple, compact system containing anti-interference abilities is preferred. In this study, a low-cost and simple-structured 1.5 μm frequency-stabilized laser is constructed using digital control methods, wavelength modulation technology, and acetylene gas absorption. The fiber input and output optical devices of the system significantly simplify the optical path and reduce the volume of the system. The error signal is obtained by the first-order differential method, and a combination of the high-speed comparator circuit and the microcontroller unit (MCU) is used to detect the error signal. Through the feedback control method of coarse temperature adjustment and fine current adjustment, the second-level frequency stability of the laser is stabilized within 100 kHz, that is, the frequency stability reaches 10​−10. The designed system achieved continuous and stable operation for more than 6 h, and the long-term frequency stability reached 10​−9.

A compensator design and stability margin monitor for digitally controlled DC-DC converters

ABSTRACT In this paper, an automatic direct digital design approach for compensators is presented to achieve a lookup table proportional – integral – derivative controller. Additionally, a correlation-based stability margin monitor with adaptive sliding window smoothing is proposed to increase the identifiable range for bandwidth detection. The proposed automatic compensator design approach meets the expected phase margin and crossover frequency and considers limit-cycle oscillation conditions throughout the design process. The digital controller with the direct digital design was implemented on a field programmable gate array to validate the approach and alternative design capabilities. Experimental results show that the direct digital design yields a higher crossover frequency than digital redesign. The best transient response performance can be obtained if a proper integral gain is designed. The digital controller with ASWS was fabricated using the TSMC 1P6M 0.18-μm standard CMOS process. Further experimental results show that the proposed ASWS provides a significantly more accurate identified frequency response by using narrow windows at low frequencies and expansive windows at high frequencies.

Development and Integration of a Digital Twin Model for a Real Hydroelectric Power Plant.

In this study, a digital twin model of a hydroelectric power plant has been created. Models of the entire power plant have been created and malfunction situations of a sensor located after the inlet valve of the plant have been analyzed using a programmable logic controller (PLC). As a feature of the digital twin (DT), the error prediction and prevention function has been studied specifically for the pressure sensor. The accuracy and reliability of the data obtained from the sensor are compared with the data obtained from the DT model. The comparison results are evaluated and erroneous data are identified. In this way, it is determined whether the malfunction occurring in the system is a real malfunction or a malfunction caused by measurement or connection errors. In the case of sensor failure or measurement-related malfunction, this situation is determined through the digital twin-based control mechanism. In the case of actual failure, the system is stopped, but in the case of measurement or connection errors, since the data are calculated by the DT model, the value in the specified region is known and thus there is no need to stop the system. This prevents production loss in the hydroelectric power plant by ensuring the continuity of the system in case of errors.

The Design and the Control Principle of a Direct Low-Speed PMSM Servo-Drive Operating under a Sign-Changing Load on the Shaft

The paper relates to the development of an algorithm applicable for maintaining the rotational speed of low-speed drives using PMSM motors and operating under a sign-changing load. The moment of inertia of rotating parts does not play the role of a mechanical stabilizer for the speeds discussed in the article. Simulation studies are presented with the aim of developing a rotational speed control algorithm that utilizes only positional feedback and the previously assumed sign-changing load on the shaft. For the purposes of this research, a mathematical model was developed to calculate transient processes in a PMSM machine operating in the conditions of a sign-changing load on the shaft. This model assumes a deterministic control principle adapted to the known nature of the load change. In this model, the mutual influence occurring between the phase fluxes, the electromagnetic torque, the electric currents and the rotor position angle are established on the basis of FEM analysis of a two-dimensional magnetic field using a quasi-stationary approximation. Principles applicable for controlling a direct low-speed servo drive based on a PMSM machine operating with a known variable shaft load using only positional feedback and a predetermined shaft load change law are defined. The proposed regulation method is verified in an experimental manner. For this purpose, an experimental setup was built, which includes a PMSM with a load imitator on a variable sign shaft, an inverter providing sine-shaped power supply to the machine and a digital dual-processor control system. The discussed rotational speed stabilization algorithm was implemented in the form of a program for a microcontroller, which forms a part of the control system. The results of experimental tests confirm the adequacy of mathematical modeling and the effectiveness of the proposed rotational speed stabilization algorithm.

Technical solution for purifying emissions of climate-active gases

The rising demand for food products and subsequent increase in agricultural production leads to heightened quantities of waste and by-products, particularly within the livestock industry. Traditional methods of livestock by-product disposal encompass intensive processing, including biodestruction processes. However, these processes tend to generate significant emissions of climate-active gases such as carbon dioxide, methane, nitrous oxide, and ammonia. To mitigate environmental impacts, it is proposed to integrate an advanced gas-air emission purification system into the existing livestock by-product processing lines. (Research purpose) The objective is to develop a system for purifying emissions of climate-active gases, particularly ammonia, produced during the intensive biotechnological processing of livestock by-products. (Materials and methods) Based on the properties of the primary pollutants, possible methods for their removal from emissions were determined. Such methods include dry, wet, condensation, and biological treatment. The biopurification method was selected for its efficacy and optimal performance. (Results and discussion) As a technical solution, a sequential gas-air emission purification process was developed using biofilters equipped with a polymer carrier and organic substrates as fillers. The system is equipped with digital sensors for monitoring and controlling the operational workflow. A special feature of the proposed system design is the use of replaceable filter cartridges and an active irrigation system. (Conclusions) The research helped to identify main types, parameters and methods for purifying emissions of climate-active gases with a focus on ammonia. Emission purification with a digital workflow control system is carried out sequentially in a shell-and-tube condenser and a biofilter. The specific cooling surface is 1.09∙10–3 square meters per 1 cubic meter, the specifi c refrigerant consumption is 0.7 liters per 1 cubic meter. Optimal biofilter performance was attained at the temperature of 30 degrees Celsius, with 45-55 percent humidity, active acidity of 8-8.4 units, and residence time of 15-30 seconds in the filter layer. These conditions ensure a high degree of ammonia purification and long-term biofilter operation.

Social impact of decarbonization objectives through smart homes: Survey and analysis

The technological development and economic growth of renewable energy are the key solution for almost full decarbonization of the energy systems. The sustainability and energy efficiency, artificial intelligence and connectivity will be the determining elements towards reaching this ambitious goal. Household appliances and tools for controlling energy consumption, temperature, lighting, etc. In the smart home will play a key role to increase awareness of families' energy consumption. IoT (Internet of Things) devices for the smart home allow us to monitor consumption and pay attention to efficiently energy use. However, savings are not the only important element of the smart home. Together with the digital control of the home these are elements that include a fundamental dimension: decarbonization, which is the cornerstone of the energy transition, which must involve an epochal change of mentality to our society where digitalization and people's well-being meet. The paper deals with social analysis of large cities population perception on integrating renewable energy sources and necessary devices to transform existing houses in smart homes towards economic wellbeing and decarbonization of the energy sector. Different classes of respondents were interviewed – owned and rented fome, rural and urban inhabitants, different segments of age, various number of inhabitants in urban areas and the capital, women and men, high-income and low-income, different levels of education – to support or disregard smart home technological development and reveal the different perception towards further usage of smart devices for daily benefits.

An Experimental Investigation on VSI-fed Induction Motor using Xilinx ZYNQ-7000 SoC Controller

In medium voltage and high-power drive applications, pulse width modulation (PWM) techniques are widely used to achieve effective speed control of AC motors. In real-time, an industrial drive system requires reduced hardware complexity and low computation time. The reliability of the AC drive can be improved with the FPGA (field programmable gate array) hardware equipped with digital controllers. To improve the performance of AC drives, a new FPGA-based Wavect real-time prototype controller (Xilinx ZYNQ-7000 SoC) is used to verify the effectiveness of the controller. These advanced controllers are capable of reducing computation time and enhancing the drive performance in real-time applications. The comparative performance analysis is carried out for the most commonly used voltage source inverter (VSI)-based PWM techniques such as sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) for three-phase, two-level inverters. The comparative study shows the SVPWM technique utilizes DC bus voltage more effectively and produces less harmonic distortion in terms of higher output voltage, flexible control of output frequency, and reduced harmonic distortion at output voltage for motor control applications. The simulation and hardware results are verified and validated by using MATLAB/Simulink software and FPGA-based Wavect real-time controller respectively.

Impedance Analysis of Digital Control Based DC–DC Converter for Both Single and Dual Control Loop

Impedance Analysis of Digital Control Based DC–DC Converter for Both Single and Dual Control Loop

Robust adaptive predictive digital controller with integral action for set-point regulation of saturated uncertain systems

A robust adaptive digital controller is systematically investigated on set-point regulation in uncertain systems under input saturation. So, an optimization strategy will be derived to solve the reference regulation robustly in the discrete-time systems. To this purpose, a discrete-time integral controller is considered through a fixed state-feedback structure. Then, its coefficients would be numerically quantified at each sample time by means of a minimization. The formulation and merit of the addressed predictive control method are theoretically proved in the paper. Then the control technique is simulated in a discrete-time equation. Additionally, some numerical results are executed to declare the remarkability and vigor of the recommended algorithm against uncertainties, actuator saturation, and disturbance in contrast to the existing control ways.

Temperature Controller of Infant Incubator using Arduino

The factors affect the child within incubator are mainly the temperature, humidity. The organization of temperatures one of the basic criteria for building a stable environment for the child. This digital temperature controller uses an Arduino board as its primary controller. It can regulate any heating device's temperature within predetermined ranges and shows the device's status, including on and off, as well as its current temperature. A temperature controller is an instrument that regulates temperature, as the name suggests. The temperature controller receives data from a temperature sensor and outputs data to a control element, like a fan or heater. In order to regulate process temperature precisely and with minimal operator intervention, a temperature control system uses a controller that receives input from a temperature sensor (such as a thermocouple, RTD, or DHT22). After comparing the actual temperature to the set-point—the desired control temperature—it outputs the result to a control element.

Promoting sleep health during pregnancy for enhancing women’s health: a longitudinal randomized controlled trial combining biological, physiological and psychological measures, Maternal Outcome after THERapy for Sleep (MOTHERS)

BackgroundSleep is vital for maintaining individuals’ physical and mental health and is particularly challenged during pregnancy. More than 70% of women during the gestational period report insomnia symptoms. Sleep dysfunction in the peripartum increases the risk for a cascade of negative health outcomes during late pregnancy, birth, and postpartum. While psychological interventions are considered the first line treatment for sleep difficulties, they are still scarcely offered during pregnancy and there is a lack of longitudinal research combining psychological and physiological indices.MethodsThe present protocol outlines a randomized controlled trial aimed at testing the long-term effectiveness of an automatized digitalized psychoeducational intervention for insomnia for expectant mothers complaining insomnia symptoms without comorbidity. Outcomes include physiological, hormonal, and subjective indices of maternal psychopathology, stress, and emotional processes, and sleep and wellbeing of the family system.The trial is part of a longitudinal study evaluating expectant mothers from early pregnancy (within the 15th gestational week) to 6-months postpartum through 6 observational phases: baseline (BSL), 6- and 12-weeks from BSL (FU1-FU2), 2-to-4 weeks after delivery (FU3), and 3- and 6-months after delivery (FU4-5). We plan to recruit 38 women without sleep difficulties (Group A) and 76 women with sleep difficulties (Group B). Group B will be randomly assigned to digital psychological control intervention (B1) or experimental psychoeducational intervention targeting insomnia (B2). At 3 time points, an ecological-momentary-assessment (EMA) design will be used to collect data on sleep and emotions (diaries), sleep-wake parameters (actigraphy) and stress reactivity (salivary cortisol). We will also test the DNA methylation of genes involved in the stress response as biomarkers of prenatal poor sleep. Information on partner’s insomnia symptoms and new-borns’ sleep will be collected at each stage.DiscussionThe proposed protocol aims at testing an easily accessible evidence-based psychoeducational intervention for expectant mothers to help them improving sleep, health, and wellbeing in the peripartum. The results could improve the understanding and management of sleep difficulties and peripartum depression.Trial registrationThe study protocol has been registered on 22 April 2024 with ClinicalTrials.gov Protocol Registration and Results System (PRS), ID: NCT06379074. Protocol version: April 23, 2024.

Multiphase LLC DC-Link Converter with Current Equalization Based on CM Voltage-Controlled Capacitor

In this study, a current-equalization technology utilizing a variable-capacitance technique for a multiphase inductor–inductor–capacitor (LLC) converter is studied. Accordingly, the proposed method involves adjusting the resonant capacitance of the LLC resonant converter to balance the currents between phases. This is achieved primarily by biasing ferroelectric multilayer ceramic capacitors (MLCCs) through a step-down circuit and a common-mode bias structure. These ferroelectric MLCCs serve as the resonant elements, allowing for variable capacitance by leveraging capacitance sensitivity to their trans voltages. This approach provides additional control flexibility to the resonant circuit. Furthermore, since each phase operates independently, the circuit can be scaled to accommodate any number of phases. Moreover, all switches in the circuit have zero-voltage switching (ZVS) turn-on, minimizing switching losses. This study initially analyzes and evaluates the proposed common-mode bias variable capacitance technique and the corresponding operational principles. Subsequently, a two-phase LLC experimental circuit based on a field-programmable gate array (FPGA) digital controller is utilized to assess current equalization and efficiency. That is to say, this experimentation aims to validate the effectiveness of the current-equalization variable-capacitance technique in an LLC resonant converter.

Circuit design solution and algorithm of digital control of processes for a universal bidirectional transistor module of switching mode voltage converter

The problem of design a universal intelligent switching mode device based on SiC transistors with built-in digital control, capable of performing various types of electrical power conversion, is formulated. The results of a study of a computer model of this device are presented, confirming the correctness of the proposed solutions. Methods for implementing parallel operation of modules are considered.