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BiFeO3–BaTiO3 (BF–BT) ceramics with high Curie temperature and excellent piezoelectric coefficient are expected to be applied in high-temperature piezoelectric sensors and actuators. However, its resistivity decreases rapidly with temperature and impedes its further applications. Moreover, normal methods such as doping modification cannot address this issue. In the present work, bismuth layered Bi4Ti2.93(Zn1/3Nb2/3)0.07O12 (BIT) and perovskite 0.36BiScO3-0.64PbTiO3 (BSPT) ceramics were selected as insulating layers and were, respectively, sintered with 0.7BF–0.3BT ceramics to form laminated ceramics. The heterojunction structures effectively prevent carrier migration, and both resistivities of BIT and BSPT laminated ceramics were increased from 106 to 108−9 Ω cm at 300 °C. In addition, piezoelectric properties of the BSPT-type laminated ceramics are much higher than that of BF–BT ceramics, in which the bipolar strain was increased from 0.04% to 0.1% (4 kV/mm), and d33 was increased from 140 to 237 pC/N. Therefore, designing the insulating layer may be an effective method to realize the high-temperature application for BF–BT ceramics. [ABSTRACT FROM AUTHOR]

BaTiO3(BT)‐templated 0.5Pb(Ni1/3Nb2/3)O3–0.16PbZrO3–0.34PbTiO3 with 0.2 wt% Li2CO3 (PNN‐PZT + LC) ceramics were successfully sintered at temperatures less than 1050°C. Their structural, ferroelectric, and piezoelectric properties were systematically investigated as a function of amount of BT, which ranged from 2 to 10 vol%. The PNN‐PZT + LC ceramics sintered at 1000°C showed highly textured morphologies with preferred (0 0 1) orientation, having Lotgering factors (fL) of 85% and higher. When sintering temperature exceeded 1000°C, the epitaxial grain growth of PNN‐PZT + LC rhombohedral phase, driven by BT templates, was hindered by dramatically enlarged matrix grains. In situ X‐ray diffractometry analyses are performed to identify phase transition behavior depending on temperature. Properties of d33 (1180 pC/N) and kp (80.3%) were obtained for the 2 vol% BT‐templated PNN‐PZT + LC ceramic sintered at 1000°C, along with ferroelectric properties of 2Pr (56.1 μC/cm2) and 2Ec (1.26 kV/mm) at 3.5 kV/mm. High‐resolution transmission electron microscopy and piezo‐response force microscopy were utilized to investigate domain structure and epitaxial grain growth between templated BaTiO3 and matrix ceramics. The low‐temperature sintered specimen showed an extremely large electrostrain characteristic (d33*) of 1215 pm/V at 1 kV/mm. Furthermore, textured multilayer piezoelectric actuators exhibited higher actuator performance and lower energy loss compared to untextured multilayer piezoelectric actuators, indicating their potential for use in piezoelectric actuator devices. [ABSTRACT FROM AUTHOR]

The miniaturization and low power consumption characteristics of RF MEMS (Radio Frequency Microelectromechanical System) switches provide new possibilities for the development of microsatellites and nanosatellites, which will play an increasingly important role in future space missions. This paper provides a comprehensive review of RF MEMS switches in satellite communication, detailing their working mechanisms, performance optimization strategies, and applications in reconfigurable antennas. It explores various driving mechanisms (electrostatic, piezoelectric, electromagnetic, thermoelectric) and contact mechanisms (capacitive, ohmic), highlighting their advantages, challenges, and advancements. The paper emphasizes strategies to enhance switch reliability and RF performance, including minimizing the impact of shocks, reducing driving voltage, improving contacts, and appropriate packaging. Finally, it discusses the enormous potential of RF MEMS switches in future satellite communications, addressing their technical advantages, challenges, and the necessity for further research to optimize design and manufacturing for broader applications and increased efficiency in space missions. The research findings of this review can serve as a reference for further design and improvement of RF MEMS switches, which are expected to play a more important role in future aerospace communication systems. [ABSTRACT FROM AUTHOR]

In this study, piezoelectric patches are used as actuators to dampen structural oscillations. Damping oscillations is a significant engineering challenge, and the use of piezoelectric patches in smart structures allows for a reduction in oscillations through sophisticated control methods. This analysis involved H-infinity (H∞) robust analysis. H∞ (H-infinity) control formulation is a robust control design method used to ensure system stability and performance under disturbances. When applied to piezoelectric actuators in smart structures, H∞ control aims to design controllers that are robust to variations in system dynamics, external disturbances, and modeling uncertainties, while meeting specified performance criteria. This study outlines the piezoelectric effects and advanced control strategies. A structural model was created using finite elements, and a smart structural model was analyzed. Subsequently, dynamic loads were applied and oscillation damping was successfully achieved by employing advanced control techniques. [ABSTRACT FROM AUTHOR]

We developed a microfluidic system for vibrational polariton studies, which consists of two microfluidic chips: one for solution mixing and another for tuning an infrared cavity made of a pair of gold mirrors and a PDMS (polydimethylsiloxane) spacer. We show that the cavity of the system can be accurately tuned with either piezoelectric actuators or microflow-induced pressure to result in resonant coupling between a cavity mode and a variational mode of the solution molecules. Acrylonitrile solutions were chosen to prove the concept of vabriational strong coupling (VSC) of a C≡N stretching mode with light inside the cavity. We also show that the Rabi splitting energy is linearly proportional to the square root of molecular concentration, thereby proving the relevance and reliability of the system for VSC studies. [ABSTRACT FROM AUTHOR]

Recently, active mounting systems have been applied to automotive engine mounts to effectively mitigate structure-borne vibrations throughout the vehicle chassis. Active mounting systems have been investigated extensively to alleviate the vibration and noise of automobiles; however, the actual engine mounting orientation is not considered, and only an extremely small range of specific vibration and noise control is examined. This paper presents the modeling, analysis, and control of a source structure with an active mounting system while considering the location and direction of actual automotive engine mounts. Two active mounts comprising a piezoelectric stack actuator arranged in series with an elastomeric mount are applied to mitigate both vertical and horizontal vibrations by setting a variable parameter via the dynamic relation of the source structure. When harmonic excitation forces are employed, the secondary force required by each active mount can be calculated mathematically, and a control signal is applied to reduce vibrations through destructive interference with the input signal. Simulation results show that the excitation vibration can be reduced using this bidirectional active mount. Hence, noise vibration harshness is expected to be improved by controlling the vibration of the actual automotive engine structure and the secondary force of actuators. [ABSTRACT FROM AUTHOR]

MEMS electrostatic actuators can suffer from a high control voltage and a limited displacement range, which are made more prevalent by the pull-in effect. This study explores a tri-electrode topology to enable a reduction in the control voltage and explores the effect of various solid materials forming the space between the two underlying stationary electrodes. Employing solid dielectric material simplifies fabrication and can reduce the bottom primary electrode's fixed voltage. Through numerical analysis, different materials were examined to assess their impact. The results indicate that the primary electrode's fixed voltage can be reduced with an increase in the dielectric constant, however, with the consequence of reduced benefit to control voltage reduction. Additionally, charge analysis was conducted to compare the actuator's performance using air as the gap-spacing material versus solid materials, from the perspective of energy conservation. It was found that solid materials result in a higher accumulated charge, reducing the need for a high fixed voltage. [ABSTRACT FROM AUTHOR]

Owing to the excellent conductivity and physical properties, graphene can significantly enhance the piezoelectric and mechanical characteristics of the piezoelectric matrix. This article studies the actuation behavior of laminated composite beams integrated with a graphene-reinforced composite piezoelectric (GRCP) actuator. Structural deformations are achieved by interlaminar stresses at interfaces between the piezoelectric actuators and the composite beams. Interlaminar stresses cannot be neglected for the structural analysis of composite beams with a GRCP actuator. Composite beams actuated by GRCP actuators exhibit more complex interlaminar mechanical behavior than traditional composite beams. Existing higher-order shear deformation theories may lose the capability for the actuation behavior of composite beams with GRCP actuators subjected to electromechanical loadings. Thereby, an advanced theory is to be proposed for the actuation performance of GRCP actuators acting on composite beams. Differing from earlier higher-order theories, the proposed theory includes an electromechanical interlaminar shear stress field that can accurately describe the distributions of interlaminar shear stresses without any additional postprocessing procedures. Additionally, a three-node beam element is constructed in terms of the proposed theory. The three-dimensional elasticity solutions, two-dimensional finite element solutions, and the results calculated by the other theories are employed to evaluate the proposed beam theory. Numerical results show that the proposed electromechanical coupling beam model can produce promising results. Additionally, the impacts of significant parameters on the actuation performance of laminated beams with a GRCP actuator are thoroughly investigated. [ABSTRACT FROM AUTHOR]

Multilayer ceramic actuators find extensive utility in applications requiring precise displacement control or force output, due to their advantages of high precision control, rapid response, low driving voltage, low power consumption, and so on. For practical applications, there is a need for high‐performance multilayer ceramic actuators (MLAs) that combine cost‐effectiveness, efficiency, and temperature stability. In this work, 1.5 mol%Sm‐doped 0.25 Pb(Mg1/3Nb2/3)O3–0.36PbZrO3–0.39PbTiO3 piezoelectric ceramics with PbO–CuO as sintering aid were fabricated. The addition of PbO–CuO significantly reduced the sintering temperature by 300°C, while having minimal impact on the piezoelectric properties. The optimized sintering condition, achieved at a low sintering temperature of 950°C with the introduction of a tiny 0.4 wt% sintering aid, yields impressive piezoelectric strain coefficient d33* = 690 pm/V. This substantiates the viability of employing low‐cost Ag/Pd (90/10) as inner electrode, which can be co‐fired with ceramic layer to fabricate MLA. This innovation enables a remarkable displacement of 1 µm at a low driving voltage of 200 V across a 9‐layers piezoelectric actuator, accompanied by high‐temperature stability, exhibiting <20% variation over the temperature range of 30–250°C. These results underscore a great potential for high‐performance piezoelectric actuators over a broad temperature range. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a miniature quadrupedal piezoelectric robot with a mass of 1.8 g and a body length of 4.6 cm. The robot adopts a novel spatial parallel mechanism as its transmission. Each leg of the robot has two degrees of freedom (DOFs): swing and lift. The trajectory necessary for walking is achieved by the appropriate phasing of these two DOFs. A new manufacturing method for piezoelectric actuators was developed. During the stacking process, discrete patterned PZT pieces are used to avoid dielectric failure caused by laser cutting. Copper-clad FR-4 is used as the solder pad instead of copper foil, making the connection between the pad and the actuator more reliable. The lift powertrain of the robot was modeled and the link length of the powertrain was optimized based on the model. The maximum output force of each leg can reach 26 mN under optimized design parameters, which is 1.38 times the required force for successful walking. The frequency response of the powertrain was measured and fitted to the second-order system, which enabled increased leg amplitudes near the powertrain resonance of approximately 70 Hz with adjusted drive signals. The maximum speed of the robot without load reached 48.66 cm/s (10.58 body lengths per second) and the payload capacity can reach 5.5 g (3.05 times its mass) near the powertrain resonance. [ABSTRACT FROM AUTHOR]

Locally resonant metamaterial beams made from flexible substrates with piezoelectric layers can exhibit bandgap and vibration attenuation properties. However, the bandgap properties of the electromechanical metamaterials are limited by the electromechanical coupling coefficient. In order to effectively overcome this limitation of the locally resonant bandgaps, a locally resonant electromechanical metamaterial beam with piezoelectric actuators and sensors is presented, and the piezoelectric shunting technique and negative proportional feedback control strategy are combined. In this design, both negative capacitance (NC) and inductance (L) are incorporated into the shunt circuits. Then, the classical root locus method is employed to obtain single/multiple bandgaps and particular structural response by arranging the poles and zeros. Finally, the influences of the feedback control gain, the shunt circuit type, and the damping ratio on the bandgap properties and wave propagation behaviors are analyzed. Numerical results demonstrate that the single/multiple bandgaps can be obviously broadened by properly increasing the control gain. Specifically, adding negative capacitance in series to pure inductive circuit can generate wider absolute bandgaps at lower frequencies. The comparison of the frequency response and the bandgap characteristics reveals a very good agreement. Summarily speaking, combining the piezoelectric shunting technique and negative proportional feedback control strategy can effectively tune the vibration and wave propagation behavior. [ABSTRACT FROM AUTHOR]

Piezoelectric actuators commonly used in microgrippers have a small stroke, and their accuracy is reduced by the transmission amplification unit, which leads to a contradiction between the clamping range and the clamping accuracy in existing piezoelectric-actuated microgrippers. This paper proposes a design scheme to divide the total clamping range of the microgripper into segments based on the compliant multistable mechanism (CMM). First, by using the stable equilibrium positions of the CMM, the total clamping range of the microgripper is divided into multiple smaller clamping sub-intervals to accommodate objects of different scales. Then, the theoretical models of the displacement amplification ratio of the microgripper amplification mechanism and the stiffness of the microgripper in different clamping sub-intervals are established, and the force-displacement characteristics of the CMM are analyzed. Next, through finite element simulation, the correctness of the theoretical analyses is verified, and it is shown that objects between 0 µm and 1.650 mm can be clamped using four clamping sub-intervals under a five times displacement amplification ratio. Finally, a microgripper of the CMM consisting of two three-segment fully compliant bistable mechanisms connected in series is designed and machined, and microgripper segmented clamping experiments are conducted. The experimental results demonstrate the feasibility of the design scheme proposed in this paper. [ABSTRACT FROM AUTHOR]

In this study, we designed an integrated fixture system using eddy current sensors and piezoelectric actuators. With this system, active supporting forces are exerted on thin-walled workpieces to adjust their stiffness in a real-time manner and thus to suppress chatter in milling. When modeling this system, we used a mass–stiffness–damping element to characterize the dynamic behavior of the actuator under high-speed responses, and we considered the electromechanical coupling between the mechanical elements and the drive circuit of the actuator. We then proposed an optimal delayed state feedback controller for the closed-loop system. The delayed state is obtained by introducing the time delay in milling dynamics into the regular state feedback, and the optimal gain is worked out through the differential quadrature and gradient descent, which is a much more computationally efficient method than the classic semi-discretization. Among all similar approaches, our strategy leads to the largest stability region for milling of thin-walled parts and requires the least energy input, which are proved by simulations and experiments. [ABSTRACT FROM AUTHOR]

Micro-vibrations significantly influence the imaging quality and pointing accuracy of high-precision space-borne payloads. To mitigate this issue, vibration isolation technology must be employed to reduce the transmission of micro-vibrations to payloads. In this paper, a novel active–passive hybrid isolation (APHI) system based on a strain sensor is proposed for high-precision space payloads, and corresponding theoretical and experimental studies are implemented. First, a theoretical analysis model of the APHI system is established using a two-degrees-of-freedom system, and an integral control method based on strain sensing is presented. Then, an electromagnetic damper, active piezoelectric actuator, and strain sensor are designed and manufactured. Finally, an APHI experimental system is implemented to validate the effectiveness of electromagnetic damping and strain-sensing active control. Additionally, the control effects of acceleration, displacement, and strain sensors are compared. The results demonstrate that strain sensors can achieve effective active damping control, and the control method based on strain sensors can effectively suppress the payload response while maintaining stability. Both displacement and strain sensors exhibit superior suppression effects compared with the acceleration sensor, with the strain sensor showing greater potential for practical engineering applications than the displacement sensor. [ABSTRACT FROM AUTHOR]

High-static-low-dynamic-stiffness (HSLDS) vibration isolators with buckling beams have been widely used to isolate external vibrations. An active adjustable device composed of proportion integration (PI) active controllers and piezoelectric actuators is proposed for improving the negative stiffness stroke of buckling beams. A nonlinear output frequency response function is used to analyze the effect of the vibration reduction. The prototype of the active HSLDS device is built, and the verification experiment is conducted. The results show that compared with the traditional HSLDS vibration isolator, the active HSLDS device can broaden the isolation frequency bandwidth, and effectively reduce the resonant amplitude by adjusting the active control parameters. The maximum vibration reduction rate of the active HSLDS vibration isolator can attain 89.9%, and the resonant frequency can be reduced from 31.08 Hz to 13.28 Hz. Therefore, this paper devotes to providing a new design scheme for enhanced HSLDS vibration isolators. [ABSTRACT FROM AUTHOR]

The characteristics of the piezo-stack and the flexible mechanism are both influenced by temperature, which induces the performance change of piezoelectric actuators in low-temperature. This study investigates how temperature affects the dynamics model's stiffness, damping, driving force, and friction. An axial heat conduction model based on Fourier's heat conduction law was established, and finite element analysis was carried out to study the temperature distribution of the piezo-stack. Moreover, finite element analysis was carried out at various temperatures to investigate the impact of temperature on the flexible mechanism's deformation. Based on the aforementioned study, a dynamics model with variable stiffness and damping is proposed in this paper, and the simulation results are verified. In the experiment, the effects of temperature, voltage, and frequency on the output performance of the piezoelectric actuator were investigated separately using impedance and amplitude-frequency characteristic curves to determine the resonant frequency and damping ratio of the flexible mechanism at low temperatures. Theory and experiment show that high stiffness and low piezoelectric constants at low temperatures reduce the piezoelectric actuator's output displacement, friction reduction will enhance the driving displacement of the piezoelectric actuator, and the effect of damping on output displacement is insignificant. This study offers significant theoretical value and guidance for the use of piezoelectric actuators in low-temperature situations. • Temperature distribution across a piezo stack via mechanical series and electrical parallel connections. • Calculate stiffness, damping, and piezo constants at low temperatures, integrate them with a dynamics model for simulation. • Assess the influence of dynamics model parameters on piezo actuators through theoretical simulations and experiments. • Clarify the effect of each parameter of the dynamics model on the performance of piezoelectric actuators by means of experimental and theoretical simulations. [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]

The robotic arm has the characteristics of multi-degree-of-freedom motion and can perform complex tasks, making it the first choice to replace manual operations in space environment. However, traditional robotic arms still face many challenges in achieving both lightweight and high precision. To overcome this, we present an integrated stator-rotor piezoelectric actuator that integrates structural and functional design, enabling substantial weight reduction and high motion accuracy. The proposed design meets the requirements of the aerospace field, making it an ideal replacement for manual operations in space. The mechanism is composed of two sets of orthogonally linked rotary joints with driven arm joints enabling rotation in two vertical directions. To reduce the impact of clamping on vibration characteristics, the vibration modes and structural parameters are optimized through simulation. The size of the fabricated prototype is 160 × 60 × 60 mm, and its weight is only 24 g. The experimental results show that the maximum motion speed of the mechanism is 620 deg/s and the stalling torque is 20 mN m at 300 Vpp. The minimum resolution can reach 25 μrad in pulse mode, and a startup and shutdown response time of 45 ms and 31 ms at 200 Vpp, respectively. These characteristics verify the correctness of the design and show that the actuator has tremendous application potential. • The actuator has the characteristics of lightweight and high precision. • Using modal optimization to reduce the impact of clamping. • The rotary joint has the characteristics of structural and functional integration. • The proposed actuator has application potential in the field of precision drive. [ABSTRACT FROM AUTHOR]

This paper proposed a feedforward-feedback (FF-FB) control strategy for a linear piezoelectric walking stage (LPWS) based on the parameter-dependent Bouc-Wen (PD-BW) model under condition variations. The mathematical model of LPWS is established by linearization, which consists of a linear system and a hysteresis nonlinearity system. The linear dynamics model of LPWS is identified by the swept-sine method, whereas the hysteresis nonlinearity model of LPWS is identified based on the PD-BW model. The feedforward controller based on the inverse PD-BW model can compensate for the inherent hysteresis nonlinearity of LPWS at varying excitation frequency, surrounding temperature, and external load. A proportional plus lead-lag feedback controller is built to reduce feedforward modelling error and improve the output accuracy of LPWS. The sensitivity analysis of the LPWS feedback control system is performed to reduce the effect of disturbance and noise. Experimental results present the feasibility and effectiveness of the proposed FF-FB control strategy to achieve an efficient and accurate positioning performance. • A feedforward-feedback control method based on the parameter-dependent Bouc-Wen model is applied to a piezoelectric stage. • The proposed parameter-dependent Bouc-Wen model compensates for the hysteresis of piezoelectric actuators under varying conditions. • The sensitivity analysis is performed to achieve accurate output performance and suppress disturbance and noise. [ABSTRACT FROM AUTHOR]

As the machine tool dynamics at the tooltip is a crucial input for chatter prediction, obtaining these dynamics for industrial applications is neither feasible through experimental impact testing for numerous tool-holder-spindle combinations nor feasible through physics-based modeling of the entire machine tool due to their sophisticated complexities and calibrations. Hence, the often-chosen path is a mathematical coupling of experimentally measured machine tool dynamics to model-predicted tool-holder dynamics. This paper introduces a novel measurement device for the experimental characterization of machine tool dynamics. The device can be simply mounted to the spindle flange to automatically capture the corresponding dynamics at the machine tool side, eliminating the need for expertise and time-consuming setup efforts thus presenting a viable solution for industries. The effectiveness of this method is evaluated against conventional spindle receptance measurement attempts using impact tests. The obtained results are further validated in the prediction of tooltip dynamics and stability boundaries. [ABSTRACT FROM AUTHOR]

Lead-based piezoelectric ceramics are the preferred material for commercial piezoelectric ceramic actuators due to their high performance and irreplaceability. However, the operating temperature (<100 °C) and strain (0.1 %∼0.2 %) of lead-based piezoelectric ceramics are still limited. Achieving large strain in a wide temperature range remains challenging. In this paper, a new strategy is proposed to effectively increase the strain value of lead-based piezoelectric ceramics through domain engineering. The new x PbTiO 3 -(0.97- x)PbZrO 3 -0.03(La 0.1 Sr 0.80.1)TiO 2.95 (x PT-PZ-LST) ternary piezoelectric ceramic system reaches a strain value as high as 0.5 % and exhibits extremely high temperature stability (13 %) in the range of 25–230 °C. By fine-tuning the content of PT components, the average length and width of a typical tetragonal domain are transformed from 800 nm to 80 nm (long and thin) to 300 nm and 200 nm (short and wide), relatively. From the experimental results of PFM and Rayleigh analysis, the high strain can be attributed to the synergistic effect of the reduced coercive field (E c), enhanced micro-region response, and regulated domain morphology, which ensures that high intrinsic and extrinsic contribution can be achieved at the same time. In this paper, a new strain regulation method is provided for lead-based piezoelectric ceramics, and a valuable large strain material is obtained via domain engineering. [ABSTRACT FROM AUTHOR]

The ability to climb is crucial for terrestrial robots to expand their scope of application with improved navigation capacity. While some soft climbing devices are available, they often lack versatility when it comes to adapting to rough surfaces and changes in terrains. In this regard, a piezo‐based soft robot with bioinspired footpads has been developed that can deliver superior climbing performance. Through their unprecedented directional friction, these footpads enable the robot to complete rigorous climbing tasks on surfaces with a climbing angle of 0–180° and a variety of roughness from ultra‐smooth to millimeter‐scale. With a unique slide‐swing gait, the robot is able to complete fast climbing on a 90° substrate at a speed of 1.4 body lengths per second (BL/s) and self‐transitional climbing on surfaces with a roughness difference of 11 µm and an angle change of 60° in 5 s without active control. A scaled down version of this climber is also presented with increased mobility to traverse steps of 3 body heights and slits of 0.75 BH effectively. In summary, the development of this soft robot with highly directional footpads paves the way for soft robots to navigate varied surfaces and ascend challenging terrains with improved mobility. [ABSTRACT FROM AUTHOR]

To detect low-frequency gravitational waves, it is necessary to eliminate the interference of geo-noise and build a laser interference gravitational-wave detection device in space. Space gravitational-wave detection missions, namely Taiji, LISA, and Tianqin, have been planning to achieve picometer sensitivity on an interferometer arm of several million kilometers to meet the gravitational-wave detection requirements. Because of the orbit evolution and the time delay in interferometer arms, the direction of the transmitted laser beam changes; consequently, a remote telescope cannot receive the laser beam to complete the inter-satellite laser interference. In this study, a two-dimensional point-ahead angle mechanism (2DPAAM) is designed and demonstrated to solve the aforementioned problem. Based on the design concept of aligning the rotation center with the mirror surface center, the 2DPAAM employs a four-link flexible-hinge structure, length expanding and contracting piezoelectric stack actuators, and closed-loop control of capacitive sensors to realize two-dimensional picometer-stable, high-precision rotation. A static model is established to analyze the rotational characteristics, and finite element analysis is performed to study the mechanical properties and to verify the rotational characteristics. The yaw and pitch stiffness errors are ∼0.93% and 5.9%, respectively, when the theoretical results are compared with the simulation results. A series of experiments are conducted on the developed 2DPAAM, and the results show that the rotary ranges of yaw and pitch motions attain ±270 and ±268 µrad, respectively. The rotational accuracies of both yaw and pitch motions attain ∼0.35 µrad, and the optical path difference is less than 10 pm / Hz when the frequency is between 1 mHz and 1 Hz, by analogy. [ABSTRACT FROM AUTHOR]

Numerous scientific satellites require micronewton thrusters for compensating environmental disturbances. The mass flow control proportional valve plays a crucial role in precisely regulating the thrust. To meet the high resolution and wide range requirements of the thrusters, this paper introduces a novel proportional valve with two sets of independently controllable piezoelectric stack. One set of the piezo-stack is used to compensate the stroke loss of the valve core, mainly caused by the deformation of the valve seat. The valve sealing mechanism is carefully analyzed to reduce the stroke loss. Another set of the stack works as the primary actuator, enabling the high mass flow control resolution. Two sets of independently controlled piezoelectric stacks not only expand the range and improve the range ratio but also provide redundancy and enhance reliability. This means that the actuator can still operate at lower ranges even if one piezo-stack is damaged. The piezo-actuators are assembled using U-shaped connectors, creating a compact and space-efficient overall design. Experimental tests have been conducted to verify the performance of the valve, which demonstrated a mass flow range of 0–675 μg/s with a resolution better than 0.1 μg/s and a flow noise below 0.1 μg/s/Hz1/2 at 0.1 mHz–1 Hz. [ABSTRACT FROM AUTHOR]

Piezoelectric thin sheets/films hold a key position in the design of some advanced electromechanical structures, such as integrated actuators, energy harvesting devices and programmable structures. The development of new advanced materials, such as metamaterials, has generated a growing interest in utilizing the nonlinear response of piezoelectric elements to achieve new desired features. Nonetheless, there has been a lack of exploration into the modelling and analysis of thin-sheet piezoelectric actuators undergoing nonlinear deformation. The current paper presents a nonlinear model of a thin-sheet piezoelectric actuator partially bonded to a linear elastic, electrically insulative host. The formulation of the problem takes into account the associated effects of the debonding and the adhesive layer on the response of the piezoelectric structure. The thin-sheet actuator is assumed as a generalized electro-elastic Euler–Bernoulli beam, characterized by the piezoelectric effect, axial and bending deformation and nonlinear deflection in the debonded part. The developed nonlinear integral equations in terms of interfacial stresses are solved using Chebyshev polynomials to determine the deformation of the actuator and the local stress fields. This nonlinear model enables the analysis of the electromechanical behaviour of actuators subjected to different in-plane electric loading, considering a range of geometries. The bending moment, axial force, displacement and interfacial stress distribution along the actuator are carefully evaluated. The current study creates valuable insights into the behaviour of such actuators with nonlinear deformation, facilitating the enhancement of actuator performance for applications in specific metamaterials. [ABSTRACT FROM AUTHOR]

In this study, we created an accurate model for a homogenous smart structure. After modeling multiplicative uncertainty, an ideal robust controller was designed using μ-synthesis and a reduced-order H-infinity Feedback Optimal Output (Hifoo) controller, leading to the creation of an improved uncertain plant. A powerful controller was built using a larger plant that included the nominal model and corresponding uncertainty. The designed controllers demonstrated robust and nominal performance when handling agitated plants. A comparison of the results was conducted. As an example of a general smart structure, the vibration of a collocated piezoelectric actuator and sensor was controlled using two different approaches with strong controller designs. This study presents a comprehensive simulation of the oscillation suppression problem for smart beams. They provide an analytical demonstration of how uncertainty is introduced into the model. The desired outcomes were achieved by utilizing Simulink and MATLAB (v. 8.0) programming tools. [ABSTRACT FROM AUTHOR]

Graphene is a highly conductive and exceptional material that has shown potential for significantly improving the piezoelectric and mechanical properties of piezoelectric matrix. This paper examines the stability of composite plates surface bonded with graphene‐reinforced composite piezoelectric (GRCP) actuators. However, the significant differences in material characteristics at the interfaces will pose some challenges in analyzing the buckling behavior of piezoelectric composite plates by means of existing higher‐order shear deformation theories. To address this issue, a refined plate theory is developed for the buckling analysis of piezoelectric composite plates. The developed theory includes a new interlaminar shear stress field that precisely describes the distribution of interlaminar shear stresses, which differs from earlier higher‐order theories. It should be emphasized that the finite element formulation can be simplified by removing the second‐order derivatives of in‐plane displacement parameters from interlaminar shear stresses. In terms of the developed theory, a four‐node C0 quadrilateral plate element is introduced to examine the buckling behavior of piezoelectric composite plates. Furthermore, the modified interlaminar shear stress field is absorbed into the strain energy, significantly improving the ability to predict the critical loads of composite plates with GRCP actuators. The refined plate model is evaluated through the utilization of three‐dimensional (3D) elasticity solutions and results obtained from other associated theories. Numerical results demonstrate that the refined plate model is capable of producing favorable results, and a comprehensive examination is conducted to analyze the effects of significant parameters on the buckling behaviors of piezoelectric composite plates. This study sets a solid foundation for future research and development on the application of graphene‐reinforced composite piezoelectric actuators in composite structures. Highlights: Buckling analysis of composite plates with GRCP actuators is conducted.A refined plate theory with modified interlaminar shear stresses is developed.The ability to predict critical loads can be significantly improved.The finite element formulation can be simplified based on the proposed model.Comprehensive parametric studies on buckling behavior are caried out. [ABSTRACT FROM AUTHOR]

Low strain limits the further application of Pb(Zr,Ti)O 3 (PZT) piezoelectric ceramics in actuators. Herein, a ternary piezoelectric ceramic x PbTiO 3 -(0.95- x)PbZrO 3 -0.05(Bi 0.5 Na 0.5)TiO 3 (x PT-PZ-BNT) is proposed and prepared by solid-state method to improve the strain characteristics. Results indicate that a biased electric field is intentionally constructed by defects arising from the incorporation of BNT into PZ-PT ceramic, which promotes non-180° domains to restore to initial states, thereby contributing to the increase in strain. Moreover, the electric domain configuration is efficiently modified by adjusting the component proportion in x PT-PZ-BNT ceramics, in which the 0.42 PT-PZ-BNT presents short and broad domains with fast response to external electric field. Rayleigh analysis indicates that the strain contributed by domain switching is dominant in PT-PZ-BNT ceramics under a high electric field. Consequently, a large strain of 0.4% is achieved in 0.42 PT-PZ-BNT ceramic with the variation less than 10% in the temperature range of 25∼175 °C. This study not only deeply analyzes the effect of domain configuration on the strain for PZT piezoelectric ceramics, but also demonstrates an effective approach to increase the strain through constructing internal biased electric field and regulating domain configuration. [ABSTRACT FROM AUTHOR]

An investigation is performed in this paper to analyze the nonlinear thermo-electro-mechanical response of long sandwich cylindrical shells with functionally graded porous (FGP) core and thin piezoelectric actuator layers. The FGP core of the sandwich shell is assumed to be temperature- and microstructure-dependent. It is assumed that the sandwich shell is subjected to uniform lateral pressure loading in a thermo-electrical environment. The equilibrium equations of the shell with infinite length are established with the aid of the virtual displacement principle and von Kármán kinematic assumptions. The governing equations are obtained in terms of displacement components based on the first-order shear deformation model of shallow cylindrical shells and the modified couple stress theory. These nonlinear differential equations are analytically solved for a sandwich shell having both the simply-supported and clamped–clamped edge conditions by employing a two-step perturbation technique. Analytical closed-form solutions are determined as a relationship including the load parameter and the mid-span deflection. The comparison examples are made with the existing results in the literature for a simple functionally graded shell, where good agreement is obtained. It is shown that the nonlinear response of the sandwich shell is highly dependent upon the temperature variation, power law index, porosity coefficient, couple stress parameter, piezoelectric layers, and geometrical parameters of the shell. [ABSTRACT FROM AUTHOR]

The 0.74Na1/2Bi1/2TiO3–0.26SrTiO3 codoped with Li2CO3 and B2O3 is studied to develop the low‐temperature sintered lead‐free piezoceramic for multilayer applications. The studied piezoceramics are synthesized by a conventional solid‐state reaction method. Their crystal structures, microstructures, ferroelectrics, and strain properties are analyzed. Interestingly, the addition of Li2CO3 and B2O3 reduces the sintering temperature of the 0.74Na1/2Bi1/2TiO3–0.26SrTiO3 sample from 1175 to 975 °C. All samples show a pseudocubic perovskite structure with a dense microstructure and an inhomogeneous grain size distribution. The electric‐field‐induced polarization loops of the samples are saturated at 4 kV mm−1. More importantly, the 0.74Na1/2Bi1/2TiO3–0.26SrTiO3 + 1 wt%Li2CO3 + 1 wt%B2O3 sample sintered at 975 °C shows a Smax/Emax value of 510 pm/V under an applied electric field of 2 kV mm−1, which is promising for multilayer lead‐free piezoelectric actuator applications. [ABSTRACT FROM AUTHOR]

Multispectral cameras (MSCs) have the capability of detecting and analyzing features invisible to human eyes and are of interest for many applications. However, the traditional MSC suffers from bulkiness since the light filtering and optical focusing mechanisms are independent. Herein, it proposed an integrated strategy that implements two functions through a tunable filtering‐focusing mechanism (TFFM), driven by two degrees of freedom (two‐DOF) piezoelectric tube actuator (PTA). The TFFM can realize light filtering and optical focusing through the rotary and linear motions of PTA. The configuration of PTA is presented, and the working principle is discussed. Then, prototypes of PTA and TFFM are developed, weighing merely 5.5 and 8 g, sizing of Ø7 × 21.4 mm and Ø35 × 7 mm, demonstrating the merits of lightweight and miniaturization. Experiments validate the effectiveness of TFFM, including multispectral images acquired with 0.1 s through rotary motion, focused images obtained with a linear speed of 60.2 mm−1s, and a series of images with different sharpness and wavelengths. The sharpness evaluation algorithms are adopted to determine the sharpest image. The work contributes to reducing the volume of MSC systems with multifunctionalities while keeping the devices simple, providing a practical and effective solution for the integrated design of MSC. [ABSTRACT FROM AUTHOR]

Nowadays, wind energy plays a central role in the renewable energy production, and the optimization of wind turbine performance is the focus of current research studies. In this context, morphing trailing edge system could be a promising solution to enhance wind turbine blades' aerodynamic performance. In this paper, an innovative morphing trailing edge system was designed, developed, and tested to improve the performance of a wind turbine blade airfoil. The trailing edge deformation is electrically operated through piezoelectric actuators and a compliant surface. Wind tunnel tests were performed for the sake of system validation at Reynolds number equal to 1.75 × 10 5 and 3.5 × 10 5 and an angle of attack ranging from − 8 ° to 8 °. The results put in evidence the effectiveness of the proposed morphing trailing edge system to enhance the aerodynamic performance. The trailing edge deformation allows to increase or decrease the lift coefficient. The mean percentage difference of lift coefficient was found equal to −83.6% and 68.4% for an upward and downward deflection, respectively. Meanwhile, the drag coefficient does not have a significant variation. Consequently, the aerodynamic efficiency will be increased or decreased keeping the angle of attack unchanged. The mean percentage difference of efficiency was found equal to −83.2% and 77.5% for an upward and downward deflection, respectively. In this way, it would be possible to optimize wind turbine blades' efficiency and production under different operating conditions. [ABSTRACT FROM AUTHOR]

A piezoelectric driven micro blower constructed with dual chamber associated with Inlet, Relay, and Outlet three orifices inside is developed. The airflow direction is perpendicular to the vibration direction of the actuator so can fabricate a thinner chamber fit for employment on a limit space of a thin device. Optimal design of piezoelectric actuator, orifice ratio and thickness, as well as the phase difference of driving signal between the actuator in each chamber to gain higher flowrate are investigated. Finite-element simulation and experiment are carried out in single chamber and then dual chamber. Both results are in a good agreement, and verify flowrate is significantly increased while using dual chamber in appropriate design and operation. An example of heat dissipation with heatsink and IC heat source employed neighboring to the exit of Outlet orifice is studied. Both the results of analytical simulation and experiment show the heatsink is cooled down to a temperature in a timespan and nearly no further temperature change. It denotes the capacity of the prototype design of dual chamber can reduce an upper limit of temperature. The temperature reduction rate is also found as a useful index for startup time assignment of the dual-chamber micro blower. [ABSTRACT FROM AUTHOR]

Based on the inverse piezoelectric effect and other characteristics of piezoelectric ceramics, a new type of piezoelectric variable friction damper is developed, and the output performance test of piezoelectric ceramic actuator and piezoelectric variable friction damper is carried out, and the parametric mechanical model of the damper is established by using Simulink to carry out numerical simulation, and compared and analyzed with the test results. The results of the study show that the simulation and the test present a good regular agreement. With the increment of loading voltage, the displacement deformation and zero-displacement thrust of piezoelectric ceramic actuator are approximately linear with the loading voltage; when the loading voltage is increased by 15V every time, the test value of the output damping force of the damper increases by 259.66N on average step by step, and the simulated value increases by 256.14N step by step, and the damping force has a linearly incremental relationship with the voltage and the slope of the linear increase is 16.434. [ABSTRACT FROM AUTHOR]

Linearity is an important factor that affects actuator accuracy. However, the high nonlinearity of KNN piezoelectric ceramics restricts their application in actuators. In this study, we used grinding stress to improve the linearity of ceramic chips, and used them to fabricate a laminated actuator. The ceramic sheets were ground to a thickness of 0.5 mm. During grinding, some areas of the ceramic changed from tetragonal to orthorhombic, owing to the grinding stress. The piezoelectric constant (d33) increased from 198 to 268 pC/N. Notably, the linearity of the ceramics improved. Seven pieces of ground ceramics were bound, to fabricate a laminated multilayer actuator with a total thickness of 3.5 mm. A DC voltage was applied to the actuator, and the displacement was measured. The displacement reached 0.73 μm under a low driving voltage of 200 V. A linear regression analysis of the displacement–voltage relationship was performed, obtaining the regression equation of the actuator. The linearity correlation coefficient was approximately 0.9903, implying that the actuator exhibits a high accuracy. The grinding stress improved the linearity, together with the piezoelectric properties of the ceramic chips, thus improving the actuator accuracy. This research will promote the application of KNN piezoelectric ceramics in actuators. [ABSTRACT FROM AUTHOR]

A novel fractional-order model, incorporating coupled hysteresis and creep effects, is proposed for typical piezoelectric actuators in this study. Throughout the actuation process, various nonlinear behaviors such as piezoelectric hysteresis, non-local memory, peak transition, and creep nonlinearity are accurately characterized by the model. Offering a simpler structure and superior tracking performance compared to conventional models, the proposed fractional-order model parameters are identified using a method that integrates actuator dynamics and employs the particle swarm optimization algorithm. Experimental validation on a piezoelectric actuation platform confirms the model's superior accuracy and simplified structure, contributing to a deeper understanding of piezoelectric actuation mechanisms and providing an efficient modeling tool for enhanced system performance. [ABSTRACT FROM AUTHOR]

Multispectral cameras (MSCs) have the capability of detecting and analyzing features invisible to human eyes and are of interest for many applications. However, the traditional MSC suffers from bulkiness since the light filtering and optical focusing mechanisms are independent. Herein, it proposed an integrated strategy that implements two functions through a tunable filtering‐focusing mechanism (TFFM), driven by two degrees of freedom (two‐DOF) piezoelectric tube actuator (PTA). The TFFM can realize light filtering and optical focusing through the rotary and linear motions of PTA. The configuration of PTA is presented, and the working principle is discussed. Then, prototypes of PTA and TFFM are developed, weighing merely 5.5 and 8 g, sizing of Ø7 × 21.4 mm and Ø35 × 7 mm, demonstrating the merits of lightweight and miniaturization. Experiments validate the effectiveness of TFFM, including multispectral images acquired with 0.1 s through rotary motion, focused images obtained with a linear speed of 60.2 mm−1s, and a series of images with different sharpness and wavelengths. The sharpness evaluation algorithms are adopted to determine the sharpest image. The work contributes to reducing the volume of MSC systems with multifunctionalities while keeping the devices simple, providing a practical and effective solution for the integrated design of MSC. [ABSTRACT FROM AUTHOR]

This paper presents the application of a hybrid approach for damage localization in concrete plates of arbitrary geometric shapes and a constant thickness. The hybrid algorithm utilizes fast discrete wavelet transformation, energy approach and time of flight criteria for the purpose of the localization of single- and multi-damage problems inside or on the periphery of concrete plates. A brief theoretical background of the hybrid method as well as numerical procedures for modeling the piezoelectric smart aggregate and ultrasonic wave propagation are presented. Experimental and numerical verification of the damage localization were performed on square samples/models with one or two damages and with 16 positions of piezoelectric smart actuator/sensor aggregates. After the verification of the hybrid method, a numerical simulation was performed on models with one or two damages for plates of arbitrary geometric shapes. Based on the obtained results, it was concluded that the proposed method can be applied to damage localization in concrete plates of arbitrary geometric shapes. The presented method and numerical procedure can be further used in research through varying the geometry, number and position of damages as well as the number and position of piezoelectric smart aggregates. [ABSTRACT FROM AUTHOR]

The subject of this article is an experimental analysis of the control system of a composite-based piezoelectric actuator and an aluminum-based piezoelectric actuator. Analysis was performed for both the unimorph and bimorph structures. To carry out laboratory research, two piezoelectric actuators with a cantilever sandwich beam structure were manufactured. In the first beam, the carrier layer was made of glass-reinforced epoxy composite (FR4), and in the second beam, it was made of 1050 aluminum. A linear mathematical model of both actuators was also developed. A modification of the method of selecting weights in the LQR control algorithm for a cantilever-type piezoelectric actuator was proposed. The weights in the R matrix for the actuator containing a carrier layer made of stiffer material should be smaller than those for the actuator containing a carrier layer made of less stiff material. Additionally, regardless of the carrier layer material, in the case of a bimorph, the weight in the R matrix that corresponds to the control voltage of the compressing MFC patch should be smaller than the weight corresponding to the control voltage of the stretching MFC patch. [ABSTRACT FROM AUTHOR]

Mechanically amplified piezoelectric actuators (APAs) can be found in many scenarios of precision engineering and instrumental devices. However, the electro-mechanical design of curvilinear APAs is difficult due to the existence of curved flexure beams and multi-domain electro-elasto dynamics. In this paper, the electro-mechanical behavior of elliptical APAs is studied by exploiting a novel electro-mechanical transfer matrix method. The motivation is to facilitate both the static and dynamic analyses of such a complex APA with curvilinear flexure beams by considering the multi-domain dynamics of piezoelectric stacks and compliant mechanisms from an electro-mechanical viewpoint. To this end, an analytical electro-elasto transfer matrix of piezoelectric stacks operating at the d 33 mode is derived in the form of Taylor's series based on Timoshenko beam theory. The dynamic response spectrum of displacement and impedance for elliptical APAs are insightfully captured by such an electro-mechanical model. Different topologies of elliptical APAs are also compared and the optimal configuration is suggested. At last, a proof-of-concept prototype is fabricated and tested with a special focus on experimental evaluation of the electro-mechanical coupling model. [Display omitted] • A new electro-elasto transfer matrix of piezoelectric stacks is derived. • Electro-mechanical analysis of elliptic-amplified piezoelectric actuators is realized. • Kinetostatics and dynamics of amplified piezoelectric actuators are involved. • Different topologies of elliptic-amplified piezoelectric actuators are compared. [ABSTRACT FROM AUTHOR]

To achieve a wide operating velocity range, stepping without backward motion, and high positioning resolution, a walking-type piezoelectric actuator with compliant mechanisms is developed. There are few academic research reports on this type of actuator, and this paper clarifies the features and advantages of this actuator. A systematic modeling and experimental evaluation of the proposed actuator are carried out. First, the configuration of the proposed actuator and the working principle of the alternating elliptical movements of the two driving feet are described. Then, dynamic models are built to simulate the output characteristics of the proposed actuator with in-phase and opposite-phase drive, which provide guidance for the design and optimization of walking-type actuators. An actuator prototype is fabricated and experimentally evaluated. The experimental results indicate that, under the opposite-phase drive, the proposed actuator can operate at a driving frequency of 1–15000 Hz. At a frequency of 14000 Hz, a maximum velocity of 24.6 mm/s is achieved at a voltage of 36 V pp , and the dead zone of the actuator is 0–6 V pp. A step displacement of 2.25 μm without backward motion is accomplished at a voltage of 72 V pp and a frequency of 1 Hz. Furthermore, the positioning resolution in the forward and reverse directions are 144 and 152 nm, respectively. The repeatability of the actuator is ±25 to ±50 nm for strokes of 325–725 nm, respectively. Therefore, compared to two driving feet being driven in phase, driving them in opposite phase as if they were walking has been confirmed to increase thrust, shorten the rise time, reduce the dead zone of driving voltage, eliminate backward motion, and provide high repeatability. • A piezoelectric actuator with triangular compliant mechanisms is first developed. • Dynamic models in the x - and y -directions are established for performance evaluation. • The actuator achieves a wide operating velocity range, no backward motion, and high-precision positioning. [ABSTRACT FROM AUTHOR]

To operate small and medium-sized helicopters even under critical icing conditions, new deicing technologies are necessary because the existing heating solutions cannot be economically downscaled without drastically reducing the helicopters' payload. Therefore, this paper investigates the potential of a low-frequency electromechanical deicing (EMDI) system for an actual fiber composite helicopter structure and its combination with an ice detection system that uses the EMDI components for ice detection. The primary objective of this study is the design of the deicing system for a given helicopter structure and its evaluation under realistic icing conditions. Experimental and numerical modal analyses are used to analyze the vibration behavior of the structure and to select favorable positions and phase relations for the actuators. To determine the performance of the EMDI system, experimental deicing tests were performed in a deicing test facility that is able to generate realistic icing conditions. The EMDI system can cause delaminations and cracks in glaze ice layers and partially remove the ice on the test object. The results show that there is an upper and lower limit for ice thickness at which the system is effective. Therefore, the system needs to be combined with an ice detection system that is capable of measuring the ice thickness on the surface of the structure. Using the piezoelectric actuators of the EMDI, this can be achieved by monitoring their impedance changes, which is experimentally proven for different ice thicknesses and different temperatures on a carbon fiber composite plate. The findings of this study support the idea of a combined ice detection and deicing system using the same hardware components. Integrating an autonomous control system, local icing phenomena on a rotorcraft structure can be detected and consequently, ice accretion can be removed with low energy consumption. [ABSTRACT FROM AUTHOR]

Stack giant magnetostrictive actuators (SGMAs) are widely used in various fields for its merits such as saving the space and improving the evenness of the bias magnetic field provided for the giant magnetostrictive material (GMM). In this paper, based on the flow path of the magnetic flux in SGMA, a magnetic equivalent network corresponding to quasistatic conditions is proposed taking flux leakage and fringing effect into account. Meanwhile, complex reluctances of the GMM rods are introduced to describe the decrease and phase shift of magnetic field intensities caused by eddy current under high-frequency excitation signals. Furthermore, the magnetic equivalent network, determining the relationship between excitation signals and magnetic field intensities, is combined with the Jiles–Atherton model, nonlinear constitutive theory of GMM concerning multi-field coupling, and structural dynamics of SGMA so as to derive a multi-field coupling model predicting the tracking behaviors of SGMA to the excitation signals. Moreover, a finite element method is conducted, an SGMA prototype is fabricated, and an experimental platform is set up to verify the proposed model. Comparison between results derived from the magnetic equivalent network and those calculated by the finite element method indicates that the proposed network is able to predict the magnetic field distribution inside the SGMA prototype in quasistatic conditions; further comparison between results obtained from the proposed multi-field coupling model and those from experiments indicates that the model can accurately predict tracking behaviors of the SGMA prototype to the excitation signals. [ABSTRACT FROM AUTHOR]