Dynamic Control Research Articles

Control of a nonlinear wave equation with a dynamic boundary condition

Existence, uniqueness, energy decay, and approximate numerical solution for the nonlinear wave equation with dynamic control at the boundary is being studied in this work. The theoretical analysis of the problem will be conducted using the Faedo-Galerkin method and compactness results. To obtain the approximate numerical solution, a combined approach of the finite element method and a finite difference method will be employed, known as the linearized Crank-Nicolson Galerkin method. This method optimizes the calculations and preserves the quadratic order of convergence in time. Finally, numerical experiments are performed, and tables and graphs are presented to illustrate the theoretical convergence rates and demonstrate the consistency between theoretical and numerical results.

Intermittent polarity inversion of stainless-steel paired electrodes for efficient and durable water electrolysis

Designing robust and cost-effective catalysts through straightforward and replicable techniques is crucial for advancing water electrolysis. In this study, we introduce a dynamic polarization control method for the continuous activation of stainless steel (SS) substrates to achieve high water-splitting performance and durability. By applying periodic inverted current density during high-current–density operation (0.5 or 1 A cm−2) on bare SS adopted as both cathode and anode substrates, a NiFe-based oxide structure favorable for the hydrogen evolution reaction is formed at the cathode, while a Fe-incorporated NiOOH structure with high efficacy for the oxygen evolution reaction develops at the anode. Implemented in an anion exchange membrane water electrolysis system, this inverted polarization approach applied for the SS paired electrolyzer system successfully maintains a cell voltage of approximately 1.9 V for 500 h at a current density of 1 A cm−2 using bare SS for both electrodes.

Adaptive practical prescribed-time control for uncertain nonlinear systems with time-varying parameters

In this paper, adaptive practical prescribed-time (PPT) control is proposed for a class of uncertain nonlinear systems with time-varying parameters and unmodeled dynamics. By constructing a novel time-varying scaling function and utilizing nonlinear mapping, the PPT control is successfully resolved. The dynamical uncertainties resulting from unmodeled dynamics are estimated by employing an auxiliary available signal, and the unknown continuous terms are handled by the aid of radial basis function neural networks (RBFNNs). A novel adaptive control method is developed by introducing the compensating signals and dynamic surface control as well as practical prescribed-time control. All the signals involved are proved to be semi-globally uniformly ultimately bounded, and the tracking error could enter the pre-specified convergence region within a pre-specified time. The robotic manipulator system is used to demonstrate the effectiveness of the proposed control approach.

A new optimal space vector modulation with DTC switching strategy for induction motor control

Efforts to achieve swift and precise dynamic torque control have been central in AC drive research. Recent advancements in embedded computer systems have highlighted direct torque control (DTC) and field-oriented control (FOC) as key methods for enhancing torque dynamics, both utilizing space vector modulation (SVM) to optimize voltage source inverter positioning. This study introduces a novel synthesis by integrating DTC with SVM to address limitations in conventional DTC, which suffers from limited voltage vector availability, leading to undesirable torque behavior and significant current fluctuations. The primary goal is to develop an optimal switching modulator for the fastest torque response through the combined application of DTC and SVM. The proposed strategy optimizes DC bus usage, reduces torque fluctuations, minimizes total harmonic distortion in AC motor current, decreases switching losses, and ensures seamless digital system integration. Simulations using MATLAB/SIMULINK demonstrate significant torque, current, and flux linkage ripple reductions, validating the approach's effectiveness. This integration overcomes established limitations, extending the capabilities of motor control methodologies and offering enhanced performance and operational integrity in induction motor drive systems.

Gaming-Based Tele-Exercise Program to Improve Physical Function in Frail Older Adults: Feasibility Randomized Controlled Trial.

Frailty leads to reduced physical activity can cause increased fall risk. This contributes to accelerated aging processes, leading to adverse health outcomes and reduced quality of life. We have developed and piloted the design, usability, safety, and feasibility of a gaming-based cognitive-motor (CogXergaming) tele-exercise protocol in prefrail older adults. This pilot randomized control trial tested preliminary feasibility and effectiveness of the CogXergaming telehealth protocol for improving physical function. Community-dwelling, prefrail older adults were randomly assigned to CogXergaming (n=13) or a control group (n=14). The CogXergaming group received supervised tele-exercises in a gaming format for 6 weeks (3 sessions per week) comprising 18 sessions lasting 90 minutes each. Control group participants participated in a Matter of Balance (MOB), an 8-week, once-a-week structured 90-minute tele-session that has been shown to reduce the fear of falling and increase physical activity. Feasibility of training was obtained by computing the median duration of training sessions for the CogXergaming group. Effectiveness was assessed using dynamic balance control (Four Square Step Test), subjective self-efficacy (Activities-Specific Balance Confidence scale), gait function (Tinetti Performance Oriented Mobility Assessment), muscle strength (30-second chair stand test), and endurance (2-minute step in-place test). Of the 45 participants enrolled in the study, 4 participants from CogXergaming group and 5 from MOB group lost contact after signing the consent form and did not receive their respective intervention. Eighteen participants were randomized to each group. In the CogXergaming group, 15 (83%) completed the intervention, with 3 (16%) dropping out in the first week. In the MOB group, 16 (88%) completed the program, with 2 (11%) withdrawing during the first week. In addition, there was a significant time group interaction for Four Square Step Test (F1,21=5.55, P=.03), Tinetti Performance Oriented Mobility Assessment (F1,25=4.16, P=.05), and 30-second chair stand test (F1,21=5.06, P=.03), with a significant improvement in these measures for the CogXergaming group post training, compared with no change observed in the MOB group. These pilot findings indicate that CogXergaming is feasible and applicable in prefrail older adults. Such game-based protocols can be beneficial in improving physical function among community-dwelling, prefrail older adults, however, the efficacy of such training requires further investigation. ClinicalTrials.gov NCT04534686; https://clinicaltrials.gov/study/NCT04534686.

Hybrid Plasmonic‐GeTe Active Metasurfaces with High Tunability

A novel hybrid plasmonic‐germanium telluride (GeTe) metasurface design, which demonstrates single‐peak on/off tunability across a spectral range of 2.5–7.5 μm is developed. Unlike previous metasurface designs utilizing GeTe layers as spacers, this study integrates GeTe as part of the meta‐atoms with gold (Au), significantly reducing the amount of GeTe required while achieving substantial on/off contrast. By varying the sizes of the meta‐atoms, different resonant wavelengths are achieved. This work represents a significant advancement in chalcogenide‐based active metasurfaces, providing precise and dynamic control over thermal emission properties.

Advanced Dynamic Vibration Control Algorithms of Materials Terfenol-D Si3N4 and SUS304 Plates/Cylindrical Shells with Velocity Feedback Control Law

A numerical, generalized differential quadrature (GDQ) method is presented on applied heat vibration for a thick-thickness magnetostrictive functionally graded material (FGM) plate coupled with a cylindrical shell. A nonlinear c1 term in the z axis direction of a third-order shear deformation theory (TSDT) displacement model is applied into an advanced shear factor and equation of motions, respectively. The equilibrium partial differential equation used for the thick-thickness magnetostrictive FGM layer plate coupled with the cylindrical shell under thermal and magnetostrictive loads can be implemented into the dynamic GDQ discrete equations. Parametric effects including nonlinear term coefficient of TSDT displacement field, advanced nonlinear varied shear coefficient, environment temperature, index of FGM power law and control gain on displacement, and stress of the thick magnetostrictive FGM plate coupled with cylindrical shell are studied. The vibrations of displacement and stress can be controlled by the control gain algorithms in velocity feedback control law.

Adaptive event-triggered dynamic output feedback control for networked autonomous vehicles affected by signal quantization and actuator failures

In this paper, an event-triggered sliding-mode output feedback control (SMOFC) strategy with adaptive fault-tolerance is proposed to achieve path tracking for networked autonomous vehicles, considering the challenges posed by network communication and electric steering systems. Initially, signal quantization, external disturbances, and actuator faults are incorporated into the vehicle model. This incorporation enhances the designed controller’s robustness against a broader and more demanding range of driving scenarios. Subsequently, in situations where only output feedback is available, a dynamic output compensator is designed to reconstruct the unmeasurable vehicle state. Utilizing the reconstructed vehicle state, an event-triggered strategy is devised to alleviate the network burden and determine the minimum time between triggering events to prevent Zeno behavior. Furthermore, an adaptive mechanism is employed to estimate the actuator fault boundaries. The performance of the designed controller is evaluated through simulation instances.

A Dynamic Control Model of Basic Oxygen Furnace Last Blowing Stage Based on Improved Conditional Generative Adversarial Network

A Dynamic Control Model of Basic Oxygen Furnace Last Blowing Stage Based on Improved Conditional Generative Adversarial Network

Adaptive prescribed‐time control for nonlinear systems with uncertain time‐varying parameters and control gains

AbstractThis article investigates the adaptive prescribed‐time dynamic surface control (PTDSC) problem for a class of nonlinear strict‐feedback systems with uncertain time‐varying parameters and unknown control gains. First, the spatiotemporal transformation method is employed to eliminate the effect of the unknown control gains in the nonlinear systems. Then, to deal with the problem of “complexity explosion” in the backstepping design framework, a novel dynamic surface control (DSC) strategy is proposed by adding a time‐varying gain to the nonlinear filter. Furthermore, under the Lyapunov stability theory, the rational adaptive laws are cleverly designed to eliminate the influence of the unknown time‐varying parameters. The PTDSC strategy proposed in this paper can guarantee that all the states of the nonlinear systems and the estimate errors of the nonlinear filters converge to zero within the prescribed time. Lastly, a simulation example is provided to demonstrate the effectiveness of the proposed control algorithm.

Dynamics Modelling and Adaptive Identification: Towards Improved Human-Robot Interaction in Collaborative Systems

This article presents a novel approach to enhancing human-robot collaboration and safety through advanced dynamic modelling and adaptive identification techniques. We introduce a comprehensive methodology that integrates motion trajectory design with real-time torque detection, addressing the critical limitations of conventional systems that rely on costly joint torque sensors. By simultaneously identifying friction forces in an integrated joint and a simplified two-bar mechanism, our approach leverages existing kinematic and dynamic models to achieve precise dynamic parameter identification. The proposed method significantly advances the fields of drag-teaching and collision detection by eliminating the need for force sensors, thus making it more feasible for mass-produced robotic systems. Our findings demonstrate that accurate dynamic modelling is essential for effective zero-force control, particularly in high-speed drag-teaching scenarios, where inertia and friction present substantial challenges. Experimental validation confirms the efficacy of our dynamic feed-forward controller design and the adaptability of drag-teaching parameters, leading to improved operational flexibility and safety in collaborative environments. This research contributes a critical framework for future developments in intelligent robotic systems, providing a robust basis for integrating advanced human-robot interactions in industrial applications.

Diversity and role of volatile terpene and terpenoid pheromones in insects.

Insect pheromones are critical chemical signals that regulate intraspecific behavior and play a key role in the dynamic monitoring and control of pest populations. Historically, research on insect pheromones has primarily focused on lipid-based compounds. However, terpenes and terpenoids, which are widely occurring classes of bioactive compounds, also play significant roles in insect pheromone blends. Over 50 terpene and terpenoid-based pheromones have been identified in over 52 insect species, spanning various orders such as Coleoptera, Hymenoptera, Blattodea, Hemiptera, Diptera, and Lepidoptera. These compounds are associated with several types of pheromones, including female or male sex pheromones, aggregation pheromones, alarm pheromones, and aphrodisiac pheromones. Terpenes and terpenoids may act as either primary or secondary components of pheromone blends and influence a wide range of critical insect behaviors. They play essential roles in the physiological and ecological adaptation of insects to their environment. This review provides a comprehensive overview of current research on terpene and terpenoid-based pheromones in insects, examining their structures, types, and physiological and ecological functions. Additionally, we propose future research directions to guide the application of these pheromones in insect behavioral regulation and pest management, while advocating for their broader use in insect pest monitoring and control.

Synthetic Biomolecular Condensates: Phase-Separation Control, Cytomimetic Modelling and Emerging Biomedical Potential.

Liquid-liquid phase separation towards the formation of synthetic coacervate droplets represents a rapidly advancing frontier in the fields of synthetic biology, material science, and biomedicine. These artificial constructures mimic the biophysical principles and dynamic features of natural biomolecular condensates that are pivotal for cellular regulation and organization. Via adapting biological concepts, synthetic condensates with dynamic phase-separation control provide crucial insights into the fundamental cell processes and regulation of complex biological pathways. They are increasingly designed with the ability to display more complex and ambitious cell-like features and behaviors, which offer innovative solutions for cytomimetic modeling and engineering active materials with sophisticated functions. In this minireview, we highlight recent advancements in the design and construction of synthetic coacervate droplets; including their biomimicry structure and organization to replicate life-like properties and behaviors, and the dynamic control towards engineering active coacervates. Moreover, we highlight the unique applications of synthetic coacervates as catalytic centers and promising delivery vehicles, so that these biomimicry assemblies can be translated into practical applications.

Dynamically patterning x-ray beam by a femtosecond optical laser.

Modern science and technology have greatly benefitted from our ability to precisely manipulate light waves, in both their spatial and temporal degrees of freedom. In the x-ray region, however, spatial control has been virtually static mainly due to stringent requirements for realizing high-performance optical elements. The lack of dynamic spatial control of x-ray beam has prevented researchers from realizing more sophisticated use of the wave field, which has rapidly advanced in the optical region in the past decades. In this study, we propose a practical scheme to dynamically control local x-ray reflectivity of a perfect silicon crystal by a femtosecond optical laser and demonstrate a programmable spatial x-ray modulator. Our modulator aims for spatial manipulation of the x-ray amplitude and is shown to produce arbitrary grayscale patterns with spatial frequencies up to 25 per millimeter. The proposed modulation scheme opens up a platform to enable advanced x-ray sensing and imaging techniques that can fully harness the wave nature of x-rays.

42 mm large aperture variable-focus lens based on the liquid-membrane-liquid structure

Variable-focus lenses enable dynamic focus control and reduce the volume of the optical systems. However, few of them have been scaled up to large apertures of 10 mm, which limits their application scenarios. Here, a variable-focus lens prototype with a 42 mm large aperture based on the liquid-membrane-liquid structure was proposed and evaluated. The prototype shows a range of adjustable optical power at [−3 D, +3 D], and demonstrates high repeatability during the operation process. The average normalized modulation transfer function value for an imaging system shows 0.7904 in 17.204 lp/mm and 0.5439 in 34.409 lp/mm. The resolution values in horizontal and vertical directions are 8 lp/mm and 8.98 lp/mm, respectively. Besides, the millisecond-level response time of the prototype is achieved with a rising edge of 5.02 ms and a falling edge of 3.66 ms. The prototype demonstrates the application scenarios of variable-focus lenses for large aperture requirements with the potential for satisfactory performance, such as in wearable devices, machine vision systems, and so on.

DNA-Regulated Multi-Protein Complement Control.

In nature, the interactions between proteins and their complements/substrates can dictate complex functions. Herein, we explore how DNA on nucleic acid modified proteins can be used as scaffolds to deliberately control interactions with a peptide complement (by adjusting length, sequence, and rigidity). As model systems, split GFPs were covalently connected through DNA scaffolds (36-58 bp). Increasing the length or decreasing the rigidity of the DNA scaffold (through removal of the duplex) increases the extent of intramolecular protein binding (up to 7.5-fold) between these GFP fragments. Independent and dynamic control over functional outputs can also be regulated by DNA hybridization; a multi-protein (split CFP and YFP) architecture was synthesized and characterized by fluorescence. This ternary construct shows that DNA displacement strands in different stoichiometric ratios can be used deliberately to regulate competitive binding between two unique sets of proteins. These studies establish a foundation for creating new classes of biological machinery based upon the concept of DNA-regulated multi-protein complement control.

Minimum Electromyography Sensor Set Needed to Identify Age-Related Impairments in the Neuromuscular Control of Walking Using the Dynamic Motor Control Index

Minimum Electromyography Sensor Set Needed to Identify Age-Related Impairments in the Neuromuscular Control of Walking Using the Dynamic Motor Control Index

Mean field control of droplet dynamics with high-order finite-element computations

Liquid droplet dynamics are widely used in biological and engineering applications, which contain complex interfacial instabilities and pattern formation such as droplet merging, splitting and transport. This paper studies a class of mean field control formulations for these droplet dynamics, which can be used to control and manipulate droplets in applications. We first formulate the droplet dynamics as gradient flows of free energies in modified optimal transport metrics with nonlinear mobilities. We then design an optimal control problem for these gradient flows. As an example, a lubrication equation for a thin volatile liquid film laden with an active suspension is developed, with control achieved through its activity field. Lastly, we apply the primal–dual hybrid gradient algorithm with high-order finite-element methods to simulate the proposed mean field control problems. Numerical examples, including droplet formation, bead-up/spreading, transport, and merging/splitting on a two-dimensional spatial domain, demonstrate the effectiveness of the proposed mean field control mechanism.

Four Quadrant Operation of Induction Motor Using H-Bridge in Harsh and Noxious Environment Field with Dust, Voltage Fluctuation and Major Load Variations

The investigation and findings show that the H Bridge variable frequency drive is the optimum choice for resolving intrinsic motor problems and energy conservation. Variable frequency drives outperform other strategies like soft starters because they offer numerous benefits over other techniques, including greater versatility and control over the motor's starting and stopping capabilities. Dynamic torque control, overload protection, and power reduction during idle are other essential aspects of variable frequency drives. Conserving energy to the greatest extent possible is one strategy to avoid energy shortages. It has been reported that 75% of the electrical energy generated globally is used by motors. It has been noted that the main problem with motors is that they use a lot of current to start. As a result, high inrush current produces excessive heat, reducing the lifespan of electrical equipment and using more electricity. Reducing the initial inrush current to a manageable level is advised. By using an induction motor and the H Bridge, this current can be decreased. H Bridge uses a technique known as variable speed drive, which is often referred to as variable torque drive, to control the speed and torque of AC induction motors. Pulse width modulation is used to monitor the motor's voltage and torque in this occurrence. Although there are several methods to reduce the motor's current, such as by employing soft starts, variable torque drives are more advantageous. The strong starting torque and flexible speed control of DC motors make them useful in a range of applications. However, because of the cost and commutation, there are a few significant problems. As a result, the PWM-powered H bridge inverter extends the life of machinery and provides electricity to electrical appliances in response to demand. The fact that it is an energy-saving gadget, however, is by far its greatest advantage. This is especially important in a country like India, where the energy crisis has halted economic growth.

Multilevel Optical Storage, Dynamic Light Modulation, and Polarization Control in Filamented Memristor System.

The electrochemical metallization (ECM) mechanism is emerging as a promising approach for the development of optical memristors-nonvolatile memory systems proposed for use as artificial synapses in neuromorphic computing applications. ECM memristors offer exceptional operating dynamics and power efficiency compared to other systems, but challenges with reproducible cycle-to-cycle state switching and the absence of advanced optical functionalities hinder their integration into photonic systems. In this work, an ECM free-standing memristor structure is proposed, which simultaneously offers wavelength-dependent multilevel nonvolatile optical storage, volatile light modulation, and dynamic polarization control. It is demonstrated that in the presence of a resonance, the optical readout provides noise-free, robust, and significantly more accurate information about the memristor's state than electrical measurement. The use of light allows to gain insight into the intermediate electrical levels of the device as it transitions between high and low resistance states and to recover the complete record of applied voltages even when stochastic filament ruptures occur. Finally, the investigations show that spectroscopic ellipsometry provides real-time information on the dynamics of cation movement and the corresponding permittivity changes at the interfaces between the switching layer and the electrodes, thus becoming a complementary characterization method for ECM memristors alongside state-of-the-art techniques.