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Owing to the practical importance of nanofluids and their adjustable thermal capabilities, this study intends to develop a robust generalized differential quadrature local linearization (GDQLL) algorithm for examining realistically the heat and mass aspects of electrically conducting nanofluids during their non-Darcian laminar motion nearby a convectively heating vertical surface of an active electromagnetic actuator (i.e., Riga plate). By invoking Wakif–Buongiorno model and Oberbeck–Boussinesq approximations along with other generalized transport laws (i.e., Cattaneo–Christov and non-Fick's laws) and Grinberg's concept, a set of gigantic partial differential equations is stated appropriately in the sense of the boundary layer approximations for describing exhaustively the present EMHD mixed convective nonhomogeneous flow under the passive control strategy of nanoparticles within the nanofluidic medium. Operationally, the dimensionless differential forms of the governing boundary equations are derived properly by introducing reasonable mathematical adjustments into the preliminary formulation. In this case, the differential complexity of the leading differential structure is reduced to a nonlinear coupled system of ordinary differential equations, whose discrete numerical solutions are computed perfectly via a well-structured GDQLL algorithm. As foremost outcomes, it is demonstrated that the nanofluid motion and its surface thermal enhancement rate can be reinforced significantly through the thermal strengthening in the convective heating and mixed convective process as well as via the electromagnetic improvement in the driven aspect of Lorentz's forces. [ABSTRACT FROM AUTHOR]

Low-frequency radiated noise, characterized by a distinctive "acoustic fingerprint" is generated when vibrations from marine machinery propagate through a ship's hull into the ocean. This type of noise travels long distances with concentrated and stable energy, posing a significant threat to a ship's acoustic stealth capabilities. Active-passive hybrid isolation is the primary method for reducing low-frequency radiated noise from ships; however, technical challenges remain, such as effectively integrating active and passive components, achieving high output force in a compact design, and addressing the poor linearity of actuator output at low frequencies. To address these issues, this paper presented an innovative electromagnetic-hydraulic-rubber integrated vibration isolator. Firstly, the study analyzed the dynamic characteristics of a two-degree-of-freedom isolation system and investigated the influence of active-passive hybrid vibration isolator parameters on control force and vibration reduction performance. Secondly, it was established that the magnetic circuit model and magnetic field strength expressions for the electromagnetic actuator using magnetic circuit analysis derive the analytical relationship between electromagnetic force, current amplitude, and frequency using the energy method. Subsequently, a mathematical model was developed for the rubber-hydraulic suspension component to examine its dynamic characteristics, hydraulic damping, and hydraulic force amplification transmission laws. Lastly, we organically combine the electromagnetic actuator with the rubber-hydraulic suspension and conduct a multi-physics joint simulation of the integrated vibration isolator using Comsol software to verify the effectiveness of the optimized design and vibration isolation control. Experimental research was carried out on the dynamic characteristics, output force properties, and fatigue characteristics of the integrated vibration isolator prototype. Results indicated that the established models and methods can achieve over 90% accuracy in predicting the performance of the electromagnetic actuator's output force and exhibit good linearity within the 5–400 Hz range. The rubber-hydraulic suspension can achieve an amplification factor of up to 1.5 for the electromagnetic force while reducing the transmission of vibrations to the base. The research findings can enhance the low-frequency vibration isolation performance of marine machinery equipment and improve their acoustic stealth capabilities. [ABSTRACT FROM AUTHOR]

To enhance the operational efficiency of hydrogen compressors and reduce the costs associated with the storage and transportation of hydrogen, this paper has developed a novel capacity control system (CCS). This system ensures that the compressor accurately compresses hydrogen according to actual demand, driven by an electromagnetic actuator, which simplifies the system design and enhances operational precision. To optimize the system's performance, a multi-objective optimization was conducted. Initially, a hydrogen compressor backflow working model and a comprehensive evaluation index system were established. Subsequently, a three-tier computational multi-objective optimization framework was proposed based on the working model, ultimately determining the optimal combination of key system parameters. A prototype was manufactured and subjected to validation testing and a full life cycle analysis. The results indicate that the developed system can accurately regulate the amount of compressed hydrogen within a range of 0%–100% load. Compared to traditional systems, for the same compressor group, carbon emissions and costs were reduced by 41.93% and 36.49%, respectively. The optimized design of the internal and external resistance angles and the limiter plate thickness are 11°, 16°, and 1 mm, respectively. Compared to the baseline state, the specific energy consumption of the hydrogen compressor per unit of exhaust volume has been reduced by 28.22%. Additionally, during the ejection and retraction processes of the actuator, the peak vibration impact on the hydrogen compressor has been reduced by 77.6% and 73.3%, respectively, achieving optimal comprehensive performance. • Developed a new CCS to enhance the operational efficiency of hydrogen compressors. • Established a backflow working model and a comprehensive evaluation index system. • Proposed a framework for multi-objective optimization. • Fabricated and tested an experimental setup for validation. [ABSTRACT FROM AUTHOR]

Milling chatter, a significant impediment to machining efficiency, adversely affects tool life and workpiece quality. To address this problem, this study presents a novel control method based on the embedded electromagnetic actuator (EMA) in the tool holder. By integrating a displacement sensor with the EMA, a comprehensive active control structure is established. System modeling and mechatronic modeling follow. Based on the results of the sweep experiments, a PD controller with optimal phase compensation is designed. During operation, this controller detects the vibration displacement of the tool holder and dampens its weak modes, thereby managing the chatter frequency. The method is validated by numerical simulations using impact and milling force identification test data. In addition, two milling experiments demonstrated the effectiveness of the method. Spindle-tool system chatter was significantly reduced, resulting in improved machining quality. In conclusion, our proposed structure and control strategy offers a powerful remedy to the challenges of milling chatter. [ABSTRACT FROM AUTHOR]

Quasi-zero-stiffness (QZS) isolator has great application potential in the field of low-frequency vibration isolation due to its high-static and low-dynamic (HSLD) nonlinear stiffness characteristic, but it is precisely this characteristic that makes it very sensitive to load changes. Once the load changes, causing it to deviate from the equilibrium position, it no longer qualifies zero-stiffness characteristic, and the vibration isolation capacity will be significantly decrease. To make the QZS isolator possess variable load capacity and be more suitable for engineering practice, an active QZS vibration isolator based on electromagnetic actuator is designed in this paper, which eliminates the influence of load changes through the active force of the electromagnetic actuator. First, the dynamic equation of the isolator is established by Newton–Euler method, and the dynamic characteristic of the isolator under standard load and load variations are analyzed through improved incremental harmonic balance (IHB) method based on discrete Fourier transform (DFT). Next, the improved particle swarm optimization (PSO) algorithm are employed to optimize the Proportion Integration Differentiation (PID) controller parameters. Then, the vibration isolation performance of QZS isolator in controlled and uncontrolled and linear systems in the same control state are compared in frequency domain and time domain, respectively. Finally, the performance of active QZS isolator under load variation is discussed. The results indicate that the isolation performance of the QZS isolator under active control is significantly better than in uncontrolled conditions and the controlled linear system. When the load changes, real-time compensation through the actuator output control force can also enable the QZS isolator to achieve a better vibration isolation performance. [ABSTRACT FROM AUTHOR]

The present work is devoted to the study of nonlinear vibrations of an electromagnetically actuated cantilever beam subject to harmonic external excitation. The soft actuator that controls the vibratory motion of such components of a robotic structure led to a strongly nonlinear governing differential equation, which was solved in this work by using a highly accurate technique, namely the Optimal Auxiliary Functions Method. Comparisons between the results obtained using our original approach with those of numerical integration show the efficiency and reliability of our procedure, which can be applied to give an explicit analytical approximate solution in two cases: the nonresonant case and the nearly primary resonance. Our technique is effective, simple, easy to use, and very accurate by means of only the first iteration. On the other hand, we present an analysis of the local stability of the model using Routh–Hurwitz criteria and the eigenvalues of the Jacobian matrix. Global stability is analyzed by means of Lyapunov's direct method and LaSalle's invariance principle. For the first time, the Lyapunov function depends on the approximate solution obtained using OAFM. Also, Pontryagin's principle with respect to the control variable is applied in the construction of the Lyapunov function. [ABSTRACT FROM AUTHOR]

This paper proposes a generalized equivalent magnetic circuit model (EMCM) considering end-effect for a moving-coil electromagnetic linear actuator (MCELA). The model describes the magnetic networks in detail by incorporating the independent variable parallel branch number and constructing them as a function of variable branch number and geometric dimensions. An iterating method to update accurate relative permeability of the soft magnetic material under different working point is also taken into consideration. The comparison study of flux density and thrust force using FEM and EMCM demonstrates the effectiveness and computation efficiency of the proposed model. Additionally, a typical MCELA prototype is implemented to further validate the proposed EMCM. The proposed method can be used for the analysis and design of a wide range of electromagnetic actuators, in addition to its application to MCELA. [ABSTRACT FROM AUTHOR]

With the advancement of manufacturing, the precision requirements for various high-precision processing equipment and instruments have further increased. Due to its noncontact nature, simple structure, and controllable performance, electromagnetic levitation has broad application prospects in ultra-precision instruments and ground testing of aerospace equipment. Research on vibration isolation technology using electromagnetic levitation is imperative. This paper reviews the latest research achievements of three types of passive isolators and five active isolation actuators. It also summarizes the current research status of analytical methods for passive isolators and the impact of isolator layout. This study explores current isolators' achievements, such as the development of passive isolators that generate negative stiffness and require mechanical springs for uniaxial translational vibrations, single-function actuators, and control systems focused on position and motion vibration control. Based on the current isolators' characteristics, this review highlights future developments, including focusing on passive isolators for heavy loads and multi-axis isolation, addressing complex vibrations, including rotational ones, and developing methods to calculate forces and torques for arbitrary six-DOF movements while improving speed. Additionally, it emphasizes the importance of multifunctional actuators to simplify system structures and comprehensive control systems that consider more environmental factors. This provides significant reference value for vibration isolation technology using electromagnetic levitation. [ABSTRACT FROM AUTHOR]

The dynamic characteristics of an electromagnetic actuator used in a switching valve are influenced by self-induced effects, resulting in instability in its parameters when subjected to changes in working frequency, load, and other conditions. To quantitatively analyze the impact of variable working conditions, this study establishes an analytical expression for periodic signals through Fourier series expansion. It subsequently solves for transient current, yielding a new model for the response of the electromagnetic actuator under periodic signal excitation. Simulations and analyses are conducted to investigate the variation in action parameters of the electromagnetic actuator in the realm of compressor gas regulation when working conditions, such as rotation speed and load force, are altered. The results indicate that dynamic characteristics of the actuator change within the range of 8% to 35%, significantly affecting the gas regulation efficiency of the compressor. To mitigate this effect, a backstepping adaptive high frequency controller (BAHF) is proposed. Comparative assessments with the backstepping adaptive sliding model controller (BASM) and backstepping adaptive high gain controller (BAHG) reveal that the BAHF exhibits superior overall performance. An experimental platform is constructed to validate both the model's accuracy and the controller's effectiveness. The error between model simulations and experiments does not exceed 7.5%, confirming the accuracy of the model. The proposed BAHF reduces the fluctuation of compression and exhaust phase angles in the compressor by 21.6% and 6.6%, respectively, under variable working conditions. This reduction effectively suppresses the influence of working condition disturbances, yielding positive outcomes. [ABSTRACT FROM AUTHOR]

The present analysis aims to scrutinize the importance of 3D viscoelastic-nanofluid having gyrotactic motile microorganisms and Cattaneo-Christov heat and mass fluxes over the Riga plate. The flow of current analysis occurs due to the stretching sheet. The Riga plate is frequently used in sophisticated sensor and magnetic lubrication structures. This is a specific electromagnetic actuator that contains a span-shaped arrangement of contrasting/alternating electrodes and a permanent magnet and allows for precise flow regulation. The technical efficiency of nanofluids is apprehended by the assessment of the Buongiorno process, which permits us to analyze the attractiveness of Brownian motion and thermophoresis diffusion. Thermal radiation has a key role in the energy equation and most of the available literature, it has been used linear. In this study, thermal radiation has been used nonlinearly. The transmuted non-linear ODE's traced with shooting technique and results of physical parameters are sketched by implementing bvp4c solver via computational software MATLAB. Numerous essential flow parameters are graphically shown to be of physical significance. The drag force, thermal gradient, concentration, and microorganism's rates are calculated under the effect of various embedded constraints. [ABSTRACT FROM AUTHOR]

Enhancing the transparency of high-transmission-ratio linear actuators is crucial for improving the safety and capability of high-force robotic systems having physical contact with humans in unstructured environments. However, realizing such enhancement is challenging. A proposed solution for active body weight support systems involves employing a macro–mini linear actuator incorporating an electrorheological-fluid brake to connect a high-force unit with an agile, highly back-drivable unit. This paper introduces the use of an electromagnetic (EM) brake with reduced rotor inertia to address this challenge. The increased torque capacity of the EM brake enables integration with a low-gear-ratio linear transmission. The agile translation of the endpoint is propelled by a low-inertia motor (referred to as the "mini") via a pulley-belt mechanism to achieve high transparency. The rotor of the EM brake is linked to the pulley. Damping modulation under high driving force is achieved through the adjustment of the brake torque relative to the rotational speed of the pulley. When the brake is engaged, it prevents any relative motion between the endpoint and the moving carrier. The endpoint is fully controlled by the ball screw of the high-force unit, referred to as the "macro". A scaled prototype was constructed to experimentally characterize the damping force generated by the mini motor and the EM brake. The macro–mini linear actuator, equipped with an intrinsic failsafe feature, can be utilized for active body weight support systems that demand high antigravity force. [ABSTRACT FROM AUTHOR]

Copyright of Dokuz Eylul University Muhendislik Faculty of Engineering Journal of Science & Engineering / Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi is the property of Dokuz Eylul Universitesi Muhendislik Fakultesi Fen ve Muhendislik Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We examine the flow of Casson hybrid nanofluid (Cu+Al2O3${\rm Al}_2{\rm O}_3$/C2H6O2${\rm C}_2{\rm H}_6{\rm O}_2$) through a Riga plate sensor with perforations that act as an electromagnetic actuator. The hypodicarbonous acid is considered a base fluid. The impact of Arrhenius chemical kinetics and viscous dissipation are taken into account during the dynamics. The problem is formulated by considering the heat and mass transfer. An appropriate scaling is used to reduce the complexity of the problem, and further transform it into a system of ordinary differential equations (ODEs). The reduced system is further set for the first‐order system of equations that are analyzed with the Artificial Neural Network (ANN) which is trained with the Levenberg–Marquardt algorithm. The results for the state variables are displayed through graphs and tables by performing 1000 independent iterations with tolerance e−12$e^{-12}$ and η=4$\eta =4$. The Hartman, Casson, and Richardson numbers with their increasing values enhance the velocity profile. The chemical reaction parameter and the Prandtl number decline the thermal and concentration profiles, respectively. The Statistical analysis in the form of regression and histograms is also carried out in each case. The absolute error (AE) ranges up to 10−10$10^{-10}$ and validations that range up to 10−11$10^{-11}$ are presented for the varying values of each parameter. A comparative analysis of the nanofluid (NF) and hybrid nanofluid (HNF) is performed in each case study. The results for skin friction and Nusselt number are displayed numerically in the form of tables and are compared with the available literature, where the accuracy and performance of ANN are proved. [ABSTRACT FROM AUTHOR]

Vibration isolators are usually used to attenuate the transmission of vibration of power machinery to the flexible foundation. Since vibration energy is transferred nearly through all the degrees of freedom of an isolator, it is difficult to guarantee sufficient vibration attenuation by the single-axis control at each active isolator. In order to enhance attenuation at each vibration isolator, a novel configuration of active vibration isolation is proposed. Each active isolator is composed of two rubber isolators and one intermediate rigid mass in which eight electromagnetic actuators and six error accelerometers are attached. Six control forces are applied on the intermediate mass to suppress its multi-axis vibration. Moreover, the weakened interaction between isolators allows independent local control at each isolator. A numerical model is established to verify the proposed active vibration isolation and the results show that the transmission of vibration from the source to the flexible hull structure can be nearly cut off when the error vibrations of each intermediate mass are attenuated completely. The effectiveness is also proved by an experimental active vibration isolation system and the proposed isolation configuration with multi-axis control can achieve more significant attenuation of vibration of the hull structure than the commonly used active vibration isolation with only single-axis control. [ABSTRACT FROM AUTHOR]

Purpose: The multi-objective optimization configuration strategy is proposed due to the configuration of EMAs in fault-tolerant control of active magnetic bearing with redundant electromagnetic actuators involving high-dimensional, nonlinear, conflicting goals. Design/methodology/approach: A multi-objective optimization model for bias current coefficients is established based on the nonlinear model of active magnetic bearings with redundant electromagnetic actuators. Based on the non-dominated sorting genetic algorithm III, a numerical method is used to obtain feasible and non-inferior sets for the bias current coefficient. Findings: (1) The conflicting relationship among the three optimization objectives was analyzed for various failure modes of EAMs. (2) For different EMAs' failure modes, the multi-objective optimization configuration strategy can simultaneously achieve the optimal or sub-optimal effective EMF, flux margins, and stability of EMF. Moreover, the characteristics of the optimal Pareto front are consistent with the physical properties of the AMB. (3) Compared with the feasible configuration of C0, the non-inferior configurations can significantly improve the performance of AMB, and the advantages of the multi-objective optimization configuration strategy become more prominent as the asymmetry of the residual supporting structure intensifies. Originality/value: i) Considering the variation of the rotor displacement during the support reconstruction, a decision-making model that can accurately characterize the dynamic performance of AMB is presented. (ii) The interaction law between AMB and rotor under different failure modes of EMAs is analyzed, and the configuration principles for redundant EMAs are proposed. (iii) Based on the dynamic characteristics of AMB during the support reconstruction, effective EMF, energy consumption, and the Pearson correlation coefficient between the desired EMFs and the decoupled control currents are used as objective functions. iv. The NSGA-III is combined with the decision-making model to address the multi-objective optimization configuration problem of C0. [ABSTRACT FROM AUTHOR]

The micro crawling robot exhibits significant potential applications in various fields such as fault detection, disaster relief, and environmental monitoring. This article introduces a high‐performance millimeter scale crawling robot driven by a miniature electromagnetic linear actuator (MELA) with a body length of 5–6 mm and a mass of 80 mg. In this article, the working principle of the micro robot is analyzed and validated, and the influence of current, frequency, and angle α between the direction of actuator's force and the crawling surface on the crawling speed are analyzed through experiments. Results show that the optimal α ranges from 50° to 55°, and a specific current and frequency are identified to achieve maximum crawling speed for robot with particular α. When α is 50°, with a current of 300 mA and a frequency of 200 Hz, the robot reached the maximum speed of 20.2 Body Length s−1(BL s−1). The proposed robot can crawl at 12 BL s−1 with a load of 110 mg, and support a maximum load of 400 mg. Additionally, the robot demonstrated diverse capabilities such as climbing on a 10° slope with a load of 110 mg, jumping on a 1 mm obstacle, and crawling on surfaces of various materials. [ABSTRACT FROM AUTHOR]

Electromagnetic actuators, characterized by their lack of pneumatic or hydraulic circuits, rapid response, and ease of control, have the potential to significantly enhance the dynamic performance of automotive active suspensions. However, the complexity associated with their models and the calibration of control parameters hampers the efficiency of control design. To address this issue, this paper proposes a reinforcement learning vibration control strategy for electromagnetic active suspension. Firstly, a half-car dynamic model with electromagnetic active suspension is established. Considering the unknown dynamics of the actuator and its preset convergence performance, an optimal control method based on reinforcement learning is investigated. Secondly, a heuristic PI adaptive dynamic programming algorithm is presented. This method can update to the optimal control solution without requiring model parameters or initial design parameters. Finally, the energy consumption and dynamic performance of this method are analyzed through rapid prototyping control simulation. The results show that the ride comfort of the vehicle suspension can be improved with the given preset convergence rate. [ABSTRACT FROM AUTHOR]

Based on the design concept of dynamic and static isolation, disturbance-free payload (DFP) satellites can isolate the effects of interference on sensitive payloads, and can realize the high-precision control of the payload better than a traditional spacecraft. Among these, non-contact annular electromagnetic stabilized spacecraft (NCAESS) can effectively alleviate control output problems such as the six-degree-of-freedom coupling and nonlinear effects found in traditional non-contact spacecraft. As a key actuator, the driving current control of the non-contact annular electromagnetic actuator (NCAEA) will have a direct impact on the attitude performance of NCAESS. However, there are multiple interference effects present in the actual driving current control. Therefore, this paper proposes a composite control scheme to improve the driving accuracy by suppressing these multiple disturbances. Firstly, the variable-switching-frequency pulse-width modulation is used to adjust the switching frequency adaptively to reduce switch ripple. Secondly, feedforward compensation is employed to mitigate the back electromotive force. Thirdly, the robust Smith predictor is utilized to compensate for the digital control delay. Finally, an internal model proportional–integral controller with fuzzy rule is applied to adjust the parameters adaptively. The numerical simulation results demonstrate that the proposed approach can be adopted to enhance the robustness and dynamic response of the driving current effectively, which leads to precise control of the non-contact annular electromagnetic stabilized spacecraft. [ABSTRACT FROM AUTHOR]

The composite electromagnetic linear actuator features a co-axial integrated design that merges the moving coil and moving iron actuator types. This design leads to significant interactions among electrical, magnetic, and thermal fields during operation, which in turn affect energy consumption and temperature increases. To further improve the material utilization rate of the actuator and optimize its comprehensive performance, such as force density and temperature rise, a multi-physical field collaborative optimization method was proposed. First, the energy consumption and temperature rise mechanisms of the actuator were analyzed. The bidirectional coupling relationships of multi-physical fields during its operation are studied. Simulations and experiments were conducted to establish the rules governing the spatiotemporal evolution of energy consumption and temperature fluctuations under standard operational conditions. Based on this, a system-level collaborative optimization model for the actuator was established. Sensitivity analysis helped segregate the design variables into system-level and independent categories. Subsequently, using a multi-objective genetic algorithm, the optimal parameter settings were determined. The optimization results revealed that the force constant of the main driving components increased by 5.4%, and the average temperature of the coil decreased by 6.3%; additionally, the starting force of auxiliary components increased by 2.3%, and the temperature of the yoke decreased by 0.8%. [ABSTRACT FROM AUTHOR]

The magnetic pulse welding method using a uniform pressure electromagnetic actuator can effectively weld dissimilar metal plates. However, the existing uniform pressure welding method leads to serious thinning of the plate at the chamfer, lack of welding at the center, and bulging of the welded sample, which seriously affects the quality of the welded joint. To solve these problems and improve the quality of welded joints, a new uniform pressure welding method of dissimilar metal plates based on pre-deformation was developed in this work. In this study, using the welding of an AA1060 aluminum plate and an SS304 steel plate with a thickness of 1 mm as an example, it was confirmed through numerical simulation and experimental research that the pre-deformation of the flyer plate controlled the impact angle of the central area of the plate, and it effectively suppressed central non-welding and serious bulge issues. Further, the welding method also reduced the height of the cushion blocks on both sides, thus mitigating aluminum plate thinning at the chamfer, ultimately improving the tensile strength of the joint. Additionally, a microscopic observation showed that the welding interface formed a wavy composite interface, and the connection strength was good. This welding method can also be extended to welding other dissimilar metal plates. [ABSTRACT FROM AUTHOR]

This paper presents the detailed design, construction and tests of a protype iron-free MRI-compatible electromagnetic actuator. The originality of this proposal lies in the use of the homogeneous static magnetic field B0, present in the MRI bore, to ensure the electromechanical energy conversion. The armature is composed of three rectangular coils in a three-phase arrangement, which makes the actuator very light-weight and compact. The operating principle is that of an AC synchronous motor with a rotating armature. In order to design the actuator, a 3D analytical electromagnetic model is developed to predict the magnetic field produced by the armature winding. Then, a 3D finite element (FE) computation is performed to validate the analytically calculated magnetic field. The developed analytical model is then inserted into an optimization routine based on Genetic Algorithms (GAs) to obtain the prototype dimensions to be realized. Finally, the prototype is constructed and tested inside an MRI research scanner. The results indicate that the reduction in the Signal-to-Noise Ratio (SNR) and the geometrical distortion are less than 5% when the actuator is powered with a current of 10 times the rated one and when it is located very close to the subject to be imaged. [ABSTRACT FROM AUTHOR]

Introduction: The mechanism of non-osseous bone conduction pathways, involving the intracranial contents (ICC) of the skull, is still not well understood. This study aimed to investigate the influence of the ICC on the skull bone wave propagation, including dependence on stimulation location and coupling. Methods: Three Thiel-embalmed whole-head cadaver specimens were studied before and after the removal of the ICC. Stimulation was via the electromagnetic actuators from commercial bone conduction hearing aids. Osseous pathways were sequentially activated by mastoid, forehead, and bone-anchored hearing aid location stimulation via a 5-Newton steel headband or percutaneously implanted screw. Non-osseous pathways were activated by stimulation on the eye and dura via a 5-Newton steel headband and a custom-made pneumatic holder, respectively. Under each test condition, the 3D motion of the superior skull bone was monitored at ∼200 points. Results: The averaged response of the skull surface showed limited differences due to the removal of the ICC. In some isolated cases, the modal pattern on the skull surface showed a trend for an upshift (∼1/2 octave) in the observed natural frequencies for drained heads. This was also consistent with an observed trend for an upshift in the transition frequency in the estimated deformation across the lateral surfaces of the temporal bones. Such changes were consistent with the expected reduction in mass and damping due to the absence of the ICC. Conclusion: Overall, the ICC affect to a limited extent the motion of the skull bone, with a limited trend for a reduction of its natural frequencies. [ABSTRACT FROM AUTHOR]

In recent years, the post‐harvest commercialization of fresh jujube sorting technology is backward, the efficiency of manual grading is low, and the application of machine vision technology in fruit grading has been a research hotspot. To improve the grading accuracy and speed of the fresh jujube machine vision grading machine, this study designs a method of fresh jujube machine vision grading using an electromagnetic synchronous actuator. The grading machine consists of an automatic distribution and arrangement system, an image acquisition and processing system, and a synchronous actuator assembly, which uses a sensitive electromagnet to adsorb a silicon steel switching buckling plate to execute the action. The image processing process includes an image color component, Sobel operator filtering, Otsu method binarization, and ellipse fitting to extract the color and size eigenvalues. The experimental results show that the date images can be acquired quickly and processed accurately with a processing speed of 50 ms per frame. In addition, the proposed actuator can be sensitively triggered with a response time of 40 ms. The grader successfully classified jujube into five size classes and one color class. The grading accuracy and non‐destructive rate reached 93.7% and 100%, respectively. The grading efficiency is 20 jujubes per second, with a maximum production rate of 1400 kilograms per hour. This grading machine realizes the requirements of high accuracy, high speed, and non‐destructive grading of fresh jujube and provides an important technical and theoretical basis for the development of machine vision jujube rapid grading technology. Practical applications: In recent years, sorting technology in the post‐harvest commercialization of fruits has been outdated, and manual grading has been inefficient. The application of machine vision technology in fruit grading has been a research hotspot in recent years. This study designs a machine vision grading of fresh dates with an electromagnetic synchronous actuator. The grader was composed of a roller conveyor, synchronous actuator assembly, image main processor, and actuator controlling co‐processor. Experimental results indicated that jujube images could be acquired rapidly and processed accurately, with a processing speed of 50 ms per frame. In addition, the proposed actuator could be sensitively triggered with a response time of 40 ms. Finally, the grader successfully sorted jujubes into five size classes and one color class. The grading accuracy rate and non‐destructive rate reached 93.7% and 100%, respectively. The grading efficiency was 20 jujubes per second, and the maximum productivity was 1400 kg/h. [ABSTRACT FROM AUTHOR]

Normal-stressed electromagnetic actuator (NSEA) has been demonstrated promising for nanopositioning stages running in hundreds of micrometers. However, system nonlinearities and their influences on the actuation behavior in NSEA have not been well revealed, blocking the in-depth understanding and high-performance application of the NSEAs. This paper developed an intrinsic electromagnetic actuation model by systematically including the nonlinear position-varying flux leakages, nonlinear flux density related to the field strength (B-H curve), and magnetic saturation. Based on the model, the influences of those nonlinear factors on the actuation were characterized theoretically. Experiments well verified the theoretical model and further characterized the dynamic hysteresis in the actuation. Finally, a phenomenological Wiener model cascading linear system dynamics with a least-squares support-vector machine (LS-SVM) model was developed for the feedforward compensation for system nonlinearities. The maximum modeling error was less than ± 4 % for the excitation with frequency ranging from 25 Hz to 200 Hz. Tracking of a complex trajectory combining multiple harmonics with various frequencies and randomly chosen amplitudes exhibited a maximum tracking error of ± 0. 7 μ m , which was only 28% of that without compensations. The results demonstrated the effectiveness of the proposed nonlinear compensation strategy for NSEAs. [Display omitted] • Intrinsic factors dominating the actuation nonlinearity are investigated for NSEAs. • Effect of the system nonlinearity on its actuation is theoretically investigated. • The nonlinearity for a NSEA stage is demonstrated experimentally. • A phenomenological model was developed for describing the system nonlinearity. [ABSTRACT FROM AUTHOR]

Friction nonlinearity and uncertainty are the main factors affecting the highly performance control of electromagnetic actuators. In this paper, a nonlinear adaptive robust control strategy is proposed of electromagnetic actuators with friction nonlinearity and uncertainty compensation. First, the dynamical model of the electromagnetic actuator is established considering nonlinearity and uncertainty. Then, an adaptive robust controller is designed based on the continuously differentiable friction model to ensure that the control input is continuously and bounded. In the design of the controller, the unfavorable effects of unknown parameters in the electromagnetic actuator are eliminated by constructing a parameter adaptive law. Meanwhile, in order to improve the tracking accuracy of the electromagnetic actuator, a nonlinear robust control law is designed to ensure the robustness of the controller. The stability analysis by Lyapunov function shows that the asymptotic tracking effect can be obtained when only parameter uncertainty exists in the closed-loop system of the electromagnetic actuator, and the consistent bounded stability can be ensured when the system also exists uncertain nonlinearity. Extensive comparative results verify the effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

For the vibration of automobile powertrain, this paper designs electro–hydraulic composite engine mounts. Subsequently, the dynamic characteristics of the hydraulic mount and the electromagnetic actuator were analyzed and experimentally studied separately. Due to the strong nonlinearity of the hybrid electromechanical engine mount, a Fractional-Order Least-Mean-Square (FGO-LMS) algorithm was proposed to model its secondary path identification. To validate the vibration reduction effect, a rapid control prototype test platform was established, and vibration active control experiments were conducted based on the Multiple–Input Multiple–Output Filter-x Least-Mean-Square (MIMO-FxLMS) algorithm. The results indicate that, under various operating conditions, the vibration transmitted to the chassis from the powertrain was significantly suppressed. [ABSTRACT FROM AUTHOR]

The vibration control is essential to suppress amplitude and improve efficiency for the marine stern shaftbearing systems. An active controller for transverse vibration is proposed by a combination of damping absorber and electromagnetic actuator with LQR strategy. The controller is designed with control methods, the parameters are defined based on the system and the disturbance input is obtained from experiments. The displacement of suspension travel and soleplate deflection, as well as the velocity of shaft and bearing is investigated. The robustness is analyzed with a pulse disturbance to study the maintenance of stability margins. The results demonstrated that the controlled behavior of the LQR strategy is preferable to that of the passive control. Moreover, the effect of damping absorber is explored through results discussion with different damping coefficient. The control weighting matrix is proved to be significant for setting time, overshoot rate and reduction rate of the controlled behavior. A smaller damping coefficient and control weighting matrix are demonstrated to be more satisfied for the control objectives. Therefore, the vibration reduction of the marine stern shaft-bearing systems can be achieved with the proposed LQR strategy. [ABSTRACT FROM AUTHOR]

To analyze the mechanical performance of the arc end tooth connection structure, the optimization of electronic sensors based on the connection structure of double rotors with circular arc end teeth was studied. By designing and optimizing the structural dimensions of the arc end tooth, the relative position of the grinding wheel and the workpiece was determined, and the optimal electromagnetic actuator size, as well as the number and installation position of the optimized sensors, were obtained. The experimental results showed that the relative error of the rigid vibration mode of the arc end tooth double rotor connection structure was controlled within 10 %. At high speeds, the electromagnetic actuator had a significant control effect on the vibration of the centrifugal machine shaft. It diminished the vibration amplitudes in the X and Y directions by 37.6 % and 30.2 %, respectively. By optimizing the double rotor connection structure with circular end teeth and electronic sensors, effective control of the relative error of rigid vibration modes has been achieved, leading to significant reduction of the centrifugal shaft's vibration at high speeds. In addition, the sensor layout was optimized to enable real-time equipment vibration monitoring, ensuring equipment safety and stability. These achievements not only enhance the mechanical performance of the rotor system, but also provide important guarantees for the stability of the mechanical system. [ABSTRACT FROM AUTHOR]

The deterioration of large steel structures, such as bridges and power generation facilities built in the 1960s, has become a problem. Such infrastructure requires regular inspections every few years, and many robots have been proposed for structural inspection. However, inspection technology for large steel structures by robots has not yet been established. The establishment of inspection technology in bridges is one of the most important issues in the maintenance of social infrastructure. This paper proposes a novel vibration actuator as a new robot drive source, which combines mechanical resonance and electromagnetic force and enables reciprocating movement by orthogonally arranging multiple vibration components. By controlling the phase difference of these vibration components with only a simple signal generator and amplifier, machine tests showed that reciprocating and rotating reciprocating motions with almost the same characteristics are possible. Experimental results reveal that the vibration actuator is able to pull a load mass of 150 g. In addition, motion analysis is conducted by applying the energy method and considering the effects of phase control on the linear and rotational motions of the vibration actuator. The results obtained in the machine test and the analysis results are mostly in agreement. This confirms that even if the parameters for the vibration actuator are varied, the linear and rotational characteristics of the actuator can be predicted by theoretical calculations. A new drive source for robots and the operation of electromagnetic motors capable of linear and rotational motion are established in this paper. For this reason, the possibility of realizing social infrastructure improvement for large steel structures such as bridges is demonstrated. [ABSTRACT FROM AUTHOR]

In laser beam processing, the angle or offset between the auxiliary gas and the laser beam axis have been proved to be two new process optimization parameters for improving cutting speed and quality. However, a traditional electromechanical actuator cannot achieve high-speed and high-precision motion control with a compact structure. This paper proposes a magnetic levitation actuator which could realize the 5-DOF motion control of a lens using six groups of differential electromagnets. At first, the nonlinear characteristic of a magnetic driving force was analyzed by establishing an analytical model and finite element calculation. Then, the dynamic model of the magnetic levitation actuator was established using the Taylor series. And the mathematical relationship between the detected distance and five-degree-of-freedom was determined. Next, the centralized control system based on PID control was designed. Finally, a driving test was carried out to verify the five-degrees-of-freedom motion of the proposed electromagnetic levitation actuator. The results show it can achieve a stable levitation and precision positioning with a desired command motion. It also proves that the proposed magnetic levitation actuator has the potential application in an off-axis laser cutting machine tool. [ABSTRACT FROM AUTHOR]

The rapid advancements in artificial intelligence, particularly in the domains of robotics, prosthetics, and virtual and augmented reality (VR/AR), have driven an escalating demand for intuitive and effective human-machine interactions. Consequently, haptic devices, being electronic displays for the sense of touch, have drawn increasing attention. More efforts are in demand to develop stretchable and lightweight haptic devices that can trigger multiple mechanical cutaneous receptors using a single device. This work presents a new 3-modal 5-DOF stretchable haptic interface that is enabled by electromagnetic actuators and high-fidelity multi-layer metal printing. The haptic device renders rich haptic sensations (i.e., normal force, vibration, angular force, skin dragging) in one device, allowing for the comprehensive delivery of tactile information through the excitation of multiple cutaneous receptors. Additionally, haptic devices are designed to be compact, lightweight, and skin-compatible. The skin-like softness and stretchability enable intimate skin contact, which is crucial for efficient haptic information delivery. This feature prevents the impediment to natural movements of the skin and ensures the functional integrity of the device during daily deformations of the skin. Finally, three proof-of-concept demonstrations illustrate the potential of the reported multimodal haptic devices for advanced haptic interactions across various domains. [ABSTRACT FROM AUTHOR]

Metasurface with programmable configurations has attracted tremendous attention due to their exotic abilities to manipulate electromagnetic waves. Herein, an electrically reconfigurable metasurface for frequency selective transmission is developed based on ionic polymer–metal composite (IPMC) kirigami. First, low‐voltage driven IPMC actuators with stable actuation performance are realized, and then a thermomechanical equivalent model and a numerical electromagnetic analysis model are proposed for evaluating the deformation of the IPMC actuators and predicting the electromagnetic tunable properties of the IPMC kirigami metasurfaces, respectively. Subsequently, large‐area IPMC kirigami metasurfaces are proposed and produced by using programmable nanosecond laser micro‐processing technique that endows the uniformity of the kirigami units. Finally, the electromagnetic functionalities of these IPMC kirigami metasurfaces are researched and validated by experiments and numerical simulations. Both theoretical and experimental results demonstrate that the electromagnetic transmission frequency of the fabricated IPMC kirigami metasurface with 10 × 10 units can be tuned from 19.3 to 20.8 GHz by the application of a low voltage of 3 V. Compared with the existing reconfigurable metasurfaces, the proposed IPMC kirigami metasurface demonstrates clear advantages in its compact structure, lower driving‐voltage, low‐acoustic noise, and wide working frequency range. [ABSTRACT FROM AUTHOR]

A novel hybrid electromagnetic-piezoelectric actuated tri-axial fast tool servo (FTS) with the hybrid serial-parallel structure is presented to satisfy the requirements of the large-stroke planar motion and the high-bandwidth vertical motion for the ultraprecision diamond turning of the complicated optical surfaces. To further improve the high-frequency spatial vibration capability, a compact three-dimensional elliptical vibration generator (3D EVG) actuated by four parallel-arranged piezoelectric actuators (PEAs) is integrated into the tri-axial FTS. The structural parameters of the proposed tri-axial FTS system are optimally designed by modeling its mechanical and electromagnetic components, and the measured mechanical performance of the resulting prototype exhibits a good agreement with the designed objective. Finally, hierarchical micro/nano-structured surfaces are fabricated by using the developed tri-axial FTS to demonstrate its comprehensively machining capacity. • A novel hybrid electromagnetic-piezoelectric actuated tri-axial FTS is proposed. • A 3D EVG actuated by four PEAs is developed and integrated into the tri-axial FTS. • The electromagnetic and mechanical components of the tri-axial FTS are modeled. • The system parameters are optimally determined by the optimization models. • Two types of hierarchically micro-structures are fabricated with the tri-axial FTS. [ABSTRACT FROM AUTHOR]

This article discusses the importance of control schemes in improving the performance and reliability of actuators. It provides an overview of various control schemes, including Model Predictive Control, Fuzzy Logic Control, and Neural Network Control, among others. The choice of control scheme depends on the system's characteristics, desired performance, and environmental conditions. The article also summarizes specific research papers that explore different control schemes in depth, covering topics such as fault diagnosis and control strategies for electric vehicles, friction compensation control for robot manipulators, and trajectory control for precision linear stages. The summary concludes by acknowledging the authors and reviewers for their contributions to the special issue. [Extracted from the article]

The Fluid Physics Research Rack (FPR) is a research platform employed on-board the Chinese Space Station for conducting microgravity fluid physics experiments. The research platform includes the Microgravity Active Vibration Isolation System (MAVIS) for isolating the FPR from disturbances arising from the space station itself. The MAVIS is a structural platform consisting of a stator and floater that are monitored and controlled with non-contact electromagnetic actuators, high-precision accelerometers, and displacement transducers. The stator is fixed to the FPR, while the floater serves as a vibration isolation platform supporting payloads, and is connected with the stator only with umbilicals that mainly comprise power and data cables. The controller was designed with a correction for the umbilical stiffness to minimize the effect of the umbilicals on the vibration isolation performance of the MAVIS. In-orbit test results of the FPR demonstrate that the MAVIS was able to achieve a microgravity level of 1–30 μg0 (where g0 = 9.80665 m ∙ s−2) in the frequency range of 0.01–125 Hz under the microgravity mode, and disturbances with a frequency greater than 2 Hz are attenuated by more than 10-fold. Under the vibration excitation mode, the MAVIS generated a minimum vibration acceleration of 0.4091 μg0 at a frequency of 0.00995 Hz and a maximum acceleration of 6253 μg0 at a frequency of 9.999 Hz. Therefore, the MAVIS provides a highly stable environment for conducting microgravity experiments, and promotes the development of microgravity fluid physics. [ABSTRACT FROM AUTHOR]

Brakes are essential parts of any system that involves motion. A few seconds are spent applying the brake, accumulating enough force to retard a system. In case of emergency stops, we need an efficient braking system that acts quickly and safely to avoid any mishaps. This work aims to develop a prototype of an instantaneous braking system, which can stop the motion of a rotating member. The operating principle of the device is the electromagnetic actuation of a solenoid. The actuation of a solenoid is simple and instantaneous. As a result, we could achieve immediate braking of a rotating member. [ABSTRACT FROM AUTHOR]

Actuators play a crucial role in microelectromechanical systems (MEMS) and hold substantial potential for applications in various domains, including reconfigurable metamaterials. This research aims to design, fabricate, and characterize structures for the actuation of the EMA. The electromagnetic actuator overcomes the lack of high drive voltage required by other actuators. The proposed actuator configuration comprises supporting cantilever beams with fixed ends, an integrated coil positioned above the cantilever's movable plate, and a permanent magnet located beneath the cantilever's movable plate to generate a static magnetic field. Utilizing flexible polyimide, the fabrication process of the EMA is simplified, overcoming limitations associated with silicon-based micromachining techniques. Furthermore, this approach potentially enables large-scale production of EMA, with displacement reaching up to 250 μm under a 100 mA current, thereby expanding their scope of applications in manufacturing. To demonstrate the function of the EMA, we integrated it with a metamaterial structure to form a compact, tunable terahertz absorber, demonstrating a potential for reconfigurable electromagnetic space. [ABSTRACT FROM AUTHOR]

An electromagnetic actuator (EMA) represents a heartening approach to take the place of an imitative mechanical actuator system in plenty of workable applications. However, it is unlikely to be functional without achieving a successful execution by designing an active positioning-controller which can stabilize the system rapidly. In this work, a new analytical algorithm for the electromagnetic actuator (EMA) system has been developed. The proposed algorithm aims to generate well-suited reference position, velocity, coil current, and coil voltage profiles that rely on the initial and final states. Firstly, the reference position and velocity are shaped by a series of exponential functions with time as the independent variable. Then, initial and steady-state position, velocity, and acceleration conditions are automatically satisfied to ensure the required reference coil current and voltage. Eventually, extensive initial actuator position dispersions are considered to perform the presented approach using the Monte-Carlo simulation method. The demonstrated results show that the suggested algorithm strategy can greatly stabilize the electromagnetic actuator with a fast response and less overshoot in the presence of wide initial position dispersions. [ABSTRACT FROM AUTHOR]

Vibration, in most cases, is an undesirable phenomenon in electro-mechanical systems. The adverse effects of vibration in a system are noise, loss of energy, compromise on comfort, and reduced life span of mechanical systems. The current study focuses on vibration damping of a Flexible Cantilever beam (FCB) by utilizing a differential type of electromagnetic actuator. The electromagnetic forces of both actuators are controlled by Pulse Width Modulation (PWM) using a current controller designed in the lab. The electromagnets are mounted above and below the FCB by maintaining a distance along the same vertical axis. The non-contact active vibration attenuation study is carried out by varying the PWM values of upper and lower electromagnets to produce different electromagnetic forces. The current research work compares different combinations of forces on upper and lower electromagnets experimentally and, based on the analysis, provides the best combination of forces on both actuators to damp the vibrations as swiftly as possible. The study is divided into three cases where case I study the vibration damping with the same PWM on both electromagnets; in case II and case III, one of the electromagnets has fixed PWM while the PWM on other electromagnet is varied. [ABSTRACT FROM AUTHOR]

Purpose: The present work proposes active vibration control in a composite material beam using electromagnetic actuators. The advantage of using electromagnetic actuators is applying control force without mechanical contact. Method: In order to evaluate the performance of the fuzzy control technique, a controller using fuzzy logic was designed. The mathematical model of the beam was obtained through the eigensystem realization algorithm/observer/Kalman identification, which consists of an identification method used to identify modal parameters in complex structures. With the obtained mathematical model, the controllers were designed, responsible for determining the control effort. Electromagnetic actuators are responsible for applying control efforts to stabilize the system. Results: The numerical simulations responses and the experimental system control responses were obtained from this. The system vibration attenuation was obtained in both procedures with three types of controllers, such that all responses were evaluated, both in the time and frequency domains. Conclusion: Finally, the robustness of the controller was analyzed from the variation inserted in the dynamic matrix of the system, thus validating the studied methodology. [ABSTRACT FROM AUTHOR]

Many technical objects use the electromagnetic DC actuators, which, unlike AC actuators, are more reliable, simpler in terms of manufacturing technology and have greater wear resistance. The listed advantages are the reason for the significant use of DC actuators in various industries including application as drive mechanisms of electrical devices. The DC actuator as a part of any technical object almost always plays one of the main roles from the point of view of reliable operation of entire device. Therefore the question of studying the designs of actuators and their characteristics is a rather topical task. Three designs of forward-moving electromagnetic DC actuators with the same overall dimensions and winding data are studied. They differ in the shapes of the supporting surfaces of poles, in other words, the surfaces with flat, conical and cut-conical shapes. As established, the shape of the supporting surfaces of poles has a significant impact on the thrust characteristics of the actuator and depending on the length of air gap this effect has a different character. The patterns of magnetic field of the studied actuators with an attracted armature are constructed, and the nature of magnetic field distribution and magnetic flux density distribution in operated gap are evaluated. The nature of the influence of cutting angle on static thrust characteristic for actuators with conical and cut-conical pole shapes is studied too. References 21, table 1, figures 7. [ABSTRACT FROM AUTHOR]

In this study, an electromagnetic actuator is presented, that features precise proportional action and wide displacement capabilities. This actuator operates in two distinct modes. In the proportional mode, the actuator positions its mobile equipment within a 0 to 14 mm range, governed by the balance between electromagnetic force and spring elastic force. By employing the pulse width modulation (PWM) principle, the electronic control section finely tunes the duty cycle factor and the coil current, thus achieving precise displacement control. The displacement control was further enhanced through the integration of a magnetic sensor that correlates movement with the Hall Voltage. This additional feature augments the actuator's precision by providing real-time feedback on the position of the mobile equipment, thereby refining the overall control mechanism. In the modulated mode, the actuator's oscillation frequency spans from 1Hz to 10 Hz, requiring control from the arbitrary signal generator. The PWM waveform controller DRV101 and the related electronic circuits are powered by two stabilized encapsulated continuous voltage sources that are compact enough to fit inside the actuator housing. The final power stage was represented by two power IGBT transistors that are powered by an external continuous voltage source. Experiments were also realized for heat management and to measure the plunger force at different distances between 0 and 14 mm. These analyses aim to optimize performance across both operational modes, advancing the efficiency and reliability of precision control systems in automated processes. [ABSTRACT FROM AUTHOR]

Abstract In order to solve the problems of complex structure and the difficulty of neutral adjustment of the existing 2D valve electro‐mechanical converter, a kind of claw pole magnetic levitation torque motor (CPMLTM) was proposed, which automatically suspended the rotor in an axially and circumferentially neutral position by using the cogging torque and axial recovery forces between the stator claw pole and the rotor permanent magnet (PM). Compared with the conventional moving iron torque motor, it has positive magnetic stiffness, 1.54 times higher PM utilisation and 33.6% lower mass. A qualitative mathematical model of output torque is derived based on equivalent magnetic circuit model. Then, the response surface method was used to build the second‐order response surface model, and NSGA‐2 was used to optimise the design of five key structural parameters, and the non‐inferior solution sets satisfying the maximisation of the cogging torque, output torque and axial recovery force were obtained. The experimental prototype was developed, and static experiments were carried out on the experimental rigs. The results show that the relationship between the input current and the output angular displacement of the CPMLTM is linearly proportional when the magnetomotive force generated by the coil winding is from −50 to 50 A.