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Purpose: Investigating the nonlinear dynamic response of giant magnetostrictive actuator (GMA) is a valuable subject in the field of precision engineering. In order to effectively control the nonlinear dynamic response of a single-degree-of-freedom GMA, a fractional-order time-lag feedback controller is designed. Methods: We model the nonlinear dynamics of the controlled GMA through the geometric nonlinearity imposed by the disc-spring mechanism and introduce the dimensionless for simplification. The flexible order adjustment capability of the Riemann–Liouville fractional-order derivatives is adopted to more accurately simulate the memory effects and nonlocal properties of the system. It effectively compensates its nonlinear dynamic behavior to optimize the system design and control. By using the averaging method, the amplitude–frequency response equations of the primary resonance in the system containing a fractional-order time-lag feedback control strategy are solved and the stability conditions are obtained. Results: Through detailed parametric studies, the effects of key structural parameters within the uncontrolled GMA and the adjustment of the parameters under fractional-order time-lag feedback control on the primary resonance response characteristics are researched. Moreover, the time-lag feedback gain and fractional-order are adjusted to effectively guide the system into the desired chaos, or to get the system out of the chaotic state and back to a stable periodic behavior. Conclusions: The research results show that the unstable region of the primary resonance curve can be significantly reduced or eliminated by choosing suitable adjustment parameters, so as to better realize accurate and reliable motion control. [ABSTRACT FROM AUTHOR]

This study introduces an integrated structural optimization design method based on a BP neural network and NSGA-II multi-objective genetic algorithm. Initially, a two-dimensional axisymmetric finite element model of the Giant Magnetostrictive Actuator (GMA) was established, and the coupling simulation of the electromagnetic field, structural field, and temperature field was conducted to obtain the GMA's performance parameters. Subsequently, the structural parameters of the GMA magnetic circuit, including the magnetic conducting ring, magnetic conducting sidewall, magnetic conducting body, and coil, were used as inputs, and the axial magnetic induction intensity, uniformity of axial magnetic induction intensity, and coil loss on the Giant Magnetostrictive Material (GMM) rod were used as outputs to establish a back propagation (BP) neural network model. This model delineated the nonlinear relationship between structural parameters and performance parameters. Then, the BP-NSGA-II algorithm was applied to perform multi-objective optimization on the actuator's structural parameters, resulting in a set of Pareto optimal non-dominated solutions, from which a set of optimal solutions was obtained using the entropy weight method. Finally, simulation analysis of this optimal solution was conducted, indicating that under a 5 A power supply excitation, the maximum axial magnetic induction intensity on the optimized GMM rod increased from 0.87 T to 1.12 T; the uniformity of axial magnetic induction intensity improved from 93.1% to 96.5%; and the coil loss decreased from 7.79 × 104 W/m3 to 4.97 × 104 W/m3. Based on the optimization results, a prototype actuator was produced, and the test results of the prototype's output characteristics proved the feasibility of this optimization design method. [ABSTRACT FROM AUTHOR]

Giant magnetostrictive powder composites (GMPCs) have important applications in electric current sensing, stress sensing, vibration damping, actuation, health monitoring and other fields. Most of the research discussed the actuation or sensing function of GMPCs merely. In this paper, GMPCs based actuator with a self-sensing function is proposed to realize direct measurement of the deformation amplitudes of the actuator in low frequency, through monitoring the voltage signal of the driving circuit. It also means the actuator can be used as a compressive stress and magnetostriction sensor. The self-sensing actuator avoids the dependence on extra sensors for actuation detection, which complements the self-sensing technique in GMPC-based actuators. It is helpful not only in the designing and controlling of self-sensing applications in actuators, but also in expanding the applications of GMPCs in the field of integrated devices. [ABSTRACT FROM AUTHOR]

In order to effectively manage the nonlinear dynamic response of giant magnetostrictive actuators (GMA), this study introduces a fractional-order time-delay feedback control scheme. Initially, we establish dimensionless dynamic equations for the controlled system, building upon prior research regarding the GMA's nonlinear dynamic model. Subsequently, we employ the averaging method to resolve the primary resonance response equation and establish stability conditions for the controlled system. Moreover, we conduct numerical simulations to examine the impact of key structural parameters within the uncontrolled system and the control system's regulating parameters, which include fractional order, feedback gain coefficient, and time-delay parameter, on the characteristics of the primary resonance response. Finally, we investigate the effects of excitation amplitude and regulating parameters on system bifurcation, chaos, and the basin of attraction. This research reveals that by selecting appropriate regulating parameters, it is possible to eliminate the jump phenomenon in the primary resonance curve, the chaos window, and chaotic attractors, thereby enhancing the system's stability. Consequently, this study lays the theoretical groundwork for implementing fractional-order time-delay feedback control within GMA systems. [ABSTRACT FROM AUTHOR]

In order to effectively control the nonlinear dynamic response of the giant magnetostrictive actuator, a design scheme based on fractional-order time-delayed feedback control is proposed in this study. The J-A hysteresis nonlinear mathematical model of the GMA system is established considering the geometric nonlinearity introduced by the precompressed disc spring mechanism. On this basis, the amplitude-frequency response equation of the main resonance of the system under the fractional-order time-delayed feedback control strategy is solved using the averaging method, and the stability conditions of the system are determined based on the Routh-Hurwitz criterion. The influence of key structural parameters on the amplitude-frequency response characteristics of the GMA system is investigated by numerical simulation, and the laws of the main resonance peak and system stability with each time-delayed feedback parameter are obtained. Further, the influence of the excitation amplitude on the chaotic motion of the system is investigated by bifurcation diagram and Lyapunov exponential diagram. Finally, the chaotic motion of the system is suppressed by adjusting the time-delayed feedback gain and fractional order. The results show that the time-delayed feedback gain and fractional order have significant effects on suppressing the main resonance peak and the unstable region of the system, and can adjust the system response from chaotic motion to stable periodic motion, thus improving the stability of the system. [ABSTRACT FROM AUTHOR]

This study introduces an integrated structural optimization design method based on a BP neural network and NSGA-II multi-objective genetic algorithm. Initially, a two-dimensional axisymmetric finite element model of the Giant Magnetostrictive Actuator (GMA) was established, and the coupling simulation of the electromagnetic field, structural field, and temperature field was conducted to obtain the GMA’s performance parameters. Subsequently, the structural parameters of the GMA magnetic circuit, including the magnetic conducting ring, magnetic conducting sidewall, magnetic conducting body, and coil, were used as inputs, and the axial magnetic induction intensity, uniformity of axial magnetic induction intensity, and coil loss on the Giant Magnetostrictive Material (GMM) rod were used as outputs to establish a back propagation (BP) neural network model. This model delineated the nonlinear relationship between structural parameters and performance parameters. Then, the BP-NSGA-II algorithm was applied to perform multi-objective optimization on the actuator’s structural parameters, resulting in a set of Pareto optimal non-dominated solutions, from which a set of optimal solutions was obtained using the entropy weight method. Finally, simulation analysis of this optimal solution was conducted, indicating that under a 5 A power supply excitation, the maximum axial magnetic induction intensity on the optimized GMM rod increased from 0.87 T to 1.12 T; the uniformity of axial magnetic induction intensity improved from 93.1% to 96.5%; and the coil loss decreased from 7.79 × 104 W/m3 to 4.97 × 104 W/m3. Based on the optimization results, a prototype actuator was produced, and the test results of the prototype’s output characteristics proved the feasibility of this optimization design method.

A rate-dependent asymmetric Prandtl–Ishilinskii (RAPI) model was proposed to tackle the serious rate-dependent hysteresis nonlinearity of the giant magnetostrictive actuator(GMA) output. First, a polynomial function was introduced based on the PI model, and hysteresis factors were introduced to the Play operator, which accurately described the asymmetrical characteristic of the actuator output. On this basis, rate-dependent parameters were added to establish a rate-dependent RAPI model. Second, an improved cuckoo search (ICS) algorithm was proposed to solve the difficulty in the parameter identification of the RAPI model. For the ICS algorithm, the algorithm stability and optimization accuracy were improved using the adaptive step (AS) strategy and bird's nest disturbance strategy. Then, the effectiveness of the ICS algorithm was tested by comparing it with other parameter identification algorithms. Finally, the rate-dependent RAPI model was verified by combining the output data of the giant magnetostrictive actuator under different frequencies. The results show that the rate-dependent RAPI model exhibits a higher accuracy than the PI model, thus verifying the effectiveness of the rate-dependent RAPI model. [ABSTRACT FROM AUTHOR]

Aiming at the contradiction between large stroke and high precision characteristics of precision positioning table, a coaxial integrated macro-micro composite actuators (MMCA) with large stroke and high precision characteristics is proposed by combining voice coil motor (VCM), and giant magnetostrictive actuator(GMA). In order to increase macro-motion stability and reduce fretting error, its structural parameters are optimized by finite element analysis, and the optimal combination mode is designed by using orthogonal experimental scheme. Finally, a model machine is developed and an experimental platform is built for performance testing. The results show that: macro external yoke(α), macro inner yoke(β), and Wall thickness of magnetic isolator(γ) it has different effects on macro-motion stability and fretting error of MMCA, When α=12mm, β=5mm, γ=12mm, the output performance of the MMCA is the best. The maximum macro-motion force of the model machine can reach 294.45N, and the maximum micro error is only 4nm. This shows that the proposed design scheme of coaxial integrated MMCA is reasonable and feasible, which lays a theoretical and technical foundation for further optimization and development of precision positioning worktable with, large stroke and high-precision characteristics.

Giant magnetostrictive actuators (GMAs) are increasingly being applied in ultra-precision motion platforms due to its high energy density, fast response and high displacement resolution. However, due to the inherent hysteresis nonlinearity of giant magnetostrictive materials, high-precision position tracking control of GMAs becomes very challenging. In this paper, a fractional-order sliding mode control (FSMC) strategy based on inverse Prandtl-Ishlinskii (PI) model (FSMC-PI) is proposed for GMAs. The inverse PI model is established to compensate for the hysteresis nonlinearity. Besides, based on the traditional sliding mode control (SMC), the proposed FSMC-PI introduces the fractional calculus term into the sliding surface, which ensures that the state converges to the fractional-order sliding manifold with fast response and small overshoot, and the position tracking performance of GMAs is enhanced. Moreover, as a feedback control method, FSMC can further effectively suppress the uncertainties and external disturbances that the inverse PI model cannot deal with. The stability of FSMC is analyzed and proved according to the Lyapunov Theorem. In addition, a double integrator is connected in series after the FSMC system, which can further improve the dynamic characteristics of the GMA system so as to guarantee the overall position tracking control performance. Finally, experiments are conducted on a GMA system with very low load, and the results demonstrate that the proposed approach can improve the position tracking performance and disturbance suppression capability more effectively, compared with four different control schemes. [ABSTRACT FROM AUTHOR]

Based on Jiles–Atherton theory and the quadratic law, a displacement model for giant magnetostrictive actuators (GMA) has been developed. The Runge–Kutta method is used to solve the nonlinear differential equation of the hysteresis model in a segmented magnetic field. Aiming at the problem that the model parameters are coupled with each other and difficult to estimate, a heuristic intelligent search algorithm-differential evolution algorithm (DE) is employed to implement parameter identification. In order to verify the effectiveness of the algorithm, comparative studies with the genetic algorithm (GA) and the particle swarm optimization (PSO) applied in parameter identification are performed. The simulation results demonstrate that the algorithm has the advantages of requiring few control variables, fast convergence speed, stable identified results, and excellent repeatability. Furthermore, the experimental results demonstrate that the output displacements calculated from the identified model are in great agreement with the measured values. Accordingly, the DE can identify the parameters of a displacement model for giant magnetostrictive actuators with satisfactory accuracy and reliability. [ABSTRACT FROM AUTHOR]

Featured Application: This study contributes to a better understanding of the dynamics of GMA systems and provides a new perspective for controlling the stable operation of GMA systems in engineering practice. Since the structural mechanics of the super magnetostrictive actuator (GMA) system involves problems related to viscoelastic damping materials, the fractional order is more accurate than the integer order calculus to characterize the viscoelastic features in the structure. In order to further investigate the intrinsic mechanism and dynamical characteristics of the GMA dynamical system, the dynamical equations of the nonlinear GMA system containing fractional damping terms are established and the main resonance of the system is analyzed using the averaging method. The mechanism of the influence of some parameters on the GMA system is analyzed by MATLAB numerical simulation to study the bifurcation and chaotic motion phenomena of the system from the qualitative and quantitative perspectives. The results show that the fractional damping coefficient, external excitation amplitude and fractional order have significant effects on the amplitude-frequency characteristics of the system; the fractional order has a greater influence on the bifurcation and chaotic behavior of the system; the dynamic behavior of the system caused by the change of external excitation amplitude and fractional damping coefficient at different damping orders is similar but the chaotic region is different. [ABSTRACT FROM AUTHOR]

Macro–micro composite-driving structures are widely used in many applications, and research has been done to improve the associated driving stroke and positioning accuracy. This article proposes a novel macro–micro composite actuator (MMCA) with a long-stroke and high-precision based on a voice coil motor (VCM) and giant magnetostrictive actuator (GMA). However, having a long stroke and high precision is contradictory. To verify this design scheme, the permanent magnet, coil, yoke, and other parts of the MMCA are designed and selected in detail. The axial and radial cross-sections of the macro-motion mechanism are studied using the magnetic equivalent circuit method. The force of the macro-motion coil is obtained based on finite element analysis (FEA). The results from both the FEA and practical experiments show the simulation results are consistent with the theoretical predictions. The maximum force of the MMCA is 53 N, the maximum displacement is 47 mm, the maximum positioning error is only $0.14~\mu \text{m}$ , and the maximum acceleration is approximately $6.7g$ , which lays a theoretical and technical foundation to provide a high-performance actuator in the field of precision manufacturing.

A rate-dependent asymmetric Prandtl–Ishilinskii (RAPI) model was proposed to tackle the serious rate-dependent hysteresis nonlinearity of the giant magnetostrictive actuator(GMA) output. First, a polynomial function was introduced based on the PI model, and hysteresis factors were introduced to the Play operator, which accurately described the asymmetrical characteristic of the actuator output. On this basis, rate-dependent parameters were added to establish a rate-dependent RAPI model. Second, an improved cuckoo search (ICS) algorithm was proposed to solve the difficulty in the parameter identification of the RAPI model. For the ICS algorithm, the algorithm stability and optimization accuracy were improved using the adaptive step (AS) strategy and bird’s nest disturbance strategy. Then, the effectiveness of the ICS algorithm was tested by comparing it with other parameter identification algorithms. Finally, the rate-dependent RAPI model was verified by combining the output data of the giant magnetostrictive actuator under different frequencies. The results show that the rate-dependent RAPI model exhibits a higher accuracy than the PI model, thus verifying the effectiveness of the rate-dependent RAPI model.

Serving as one of the core component, the excitation coil can exert remarkable influence on the output performance of giant magnetostrictive actuator (GMA) for electronic controlled fuel injector. In this paper, a multi-objective coil optimization scheme is proposed to balance the conflicting response speed and magnetic field intensity determined by the coil parameters. Firstly, a physics-based coil model is established for optimization, whose parameters can be directly calculated by the coil dimensions. Then, with the current response of the coil calculated, a multi-objective optimization framework is conducted attempting to get the selection guideline for the enameled wire diameter of the coil. The optimal choices exist when the outer diameter of the enameled wire falls in 0.9∼1.6 mm, and the inner/outer diameter ratio is relatively high. Finally, a series of experiments are conducted and the results indicate that the proposed model is able to accurately describe the current response throughout the operating frequencies, and the optimization scheme can provide a valuable roadmap to design coil for high performance GMA. [ABSTRACT FROM AUTHOR]

A time-delayed displacement and velocity feedback controller is designed to control the nonlinear dynamic characteristics, particularly principal resonance response, chaotic motion, and limit cycle amplitude, of a single-degree-of-freedom giant magnetostrictive actuator (GMA) system, thereby improving the stability of the system. This controller is established using the previously reported mechanical model of GMA system based on its structure and working principle. Further, the multi-scale method is used to solve the amplitude–frequency response equation and obtain the stability conditions for the time-delayed feedback control of the system's primary resonance. The influence of each time-delayed feedback parameter on the stability of the primary resonance, chaotic motion, and limit cycle amplitude is examined. The results show that the displacement feedback gain coefficient can only shift the resonance curve to the left and right, while the velocity feedback gain coefficient and time delay parameters can effectively improve the stability and suppress the nonlinear vibration of the system. By increasing the negative displacement feedback gain coefficient and the negative velocity feedback gain coefficient, the system response can be tuned from chaotic motion to periodic motion. The feedback gain coefficient can be effectively used to control the amplitude of the limit loop of the system. Overall, by selecting appropriate time-delayed feedback parameters, the multi-valued solution of the primary resonance can be avoided, the stability of the system can be improved, the chaotic motion can be circumvented, and the limit cycle amplitude can be controlled. [ABSTRACT FROM AUTHOR]

The internal magnetic field characteristics of giant magnetostrictive actuators have an important influence on their output performance. Aiming at the deficiency of current scholars' research, based on the electromagnetic theory and finite element method, this paper analyzes the magnetic field intensity on a giant magnetostrictive cylinder by using COMSOL Multiphysics software. Considering the inhomogeneity of magnetic field intensity along the radial direction of giant magnetostrictive cylinders, a new averaging method is introduced to calculate the magnetic field intensity in the axial section of the cylinder. The influence of the magnetic permeability of the displacement conversion mechanism (shell) and the size of the air gap inside the device on the magnetic field intensity of the giant magnetostrictive cylinder are analyzed. The prototype of the actuator is manufactured, and the correctness and accuracy of the simulation data are verified by experiments. In order to make the magnetic field on the cylinder strong and uniform, the displacement conversion mechanism and the shell should be made of low permeability and high permeability materials, respectively, and the air gap size should be reduced as much as possible under the condition of meeting the size requirement of the actuator pre-tightening force applying device. [ABSTRACT FROM AUTHOR]

Based on Jiles–Atherton theory and the quadratic law, a displacement model for giant magnetostrictive actuators (GMA) has been developed. The Runge–Kutta method is used to solve the nonlinear differential equation of the hysteresis model in a segmented magnetic field. Aiming at the problem that the model parameters are coupled with each other and difficult to estimate, a heuristic intelligent search algorithm-differential evolution algorithm (DE) is employed to implement parameter identification. In order to verify the effectiveness of the algorithm, comparative studies with the genetic algorithm (GA) and the particle swarm optimization (PSO) applied in parameter identification are performed. The simulation results demonstrate that the algorithm has the advantages of requiring few control variables, fast convergence speed, stable identified results, and excellent repeatability. Furthermore, the experimental results demonstrate that the output displacements calculated from the identified model are in great agreement with the measured values. Accordingly, the DE can identify the parameters of a displacement model for giant magnetostrictive actuators with satisfactory accuracy and reliability.

Since the structural mechanics of the super magnetostrictive actuator (GMA) system involves problems related to viscoelastic damping materials, the fractional order is more accurate than the integer order calculus to characterize the viscoelastic features in the structure. In order to further investigate the intrinsic mechanism and dynamical characteristics of the GMA dynamical system, the dynamical equations of the nonlinear GMA system containing fractional damping terms are established and the main resonance of the system is analyzed using the averaging method. The mechanism of the influence of some parameters on the GMA system is analyzed by MATLAB numerical simulation to study the bifurcation and chaotic motion phenomena of the system from the qualitative and quantitative perspectives. The results show that the fractional damping coefficient, external excitation amplitude and fractional order have significant effects on the amplitude-frequency characteristics of the system; the fractional order has a greater influence on the bifurcation and chaotic behavior of the system; the dynamic behavior of the system caused by the change of external excitation amplitude and fractional damping coefficient at different damping orders is similar but the chaotic region is different.

Aiming at the inherent problems of non-direct-drive injectors, such as long oil circuits and a difficult precise control of the needle stroke, based on the structure of a direct-drive injector and combined with the demand for the needle drive of a truck diesel injector, this study designs and fabricates a giant magnetostrictive actuator for direct-drive injectors. A simplified model of a giant magnetostrictive actuator is established, which mainly simplifies the magnetization model to facilitate the subsequent integrated modeling of the fuel injector. An actuator output displacement test system was built, and the output waveform and frequency characteristics of the actuator were analyzed. It was found that the experimental results were in good agreement with the calculated results of the model, and the average relative error of the amplitude was 3.26%, while the average relative error of the phase difference was 3.83%, which verifies the correctness of the model. This research enriches the modeling method of giant magnetostrictive actuators and has an important reference value for the research and design of fuel injectors.

Background: A lot of efforts have been devoted to the instrument development of simultaneous precision positioning and vibration control for on-orbit optical payloads. However, only series schemes with two active elements which, in fact, are coarse and fine hybrid mechanisms, are researched in despite of adverse impacts on the whole mass and dimensions, control strategy and energy usage. Thus, a new magnetostrictive integrated actuator with just one single active element is proposed to realize those two functions together. Methods: The detailed scheme is introduced, and the selection of some key parameters are explained first. Then, the explicit expressions are derived and the performances are preliminarily studied by numerical simulations. Finally, a prototype is fabricated, and experimental tests are carried out in view of external disturbances with different frequencies. Conclusions: The results indicate that the developed actuator can not only actively control the low-frequency disturbances but also can passively suppress the middle-high frequency micro-vibrations during precision positioning. [ABSTRACT FROM AUTHOR]

In this study, a new method of using giant magnetostrictive actuator (GMA) to control the structural vibration of a space solar power station (SSPS) in orbit is proposed. The coupling dynamic model of SSPS, which is simplified into an Euler–Bernoulli beam with both free ends, is established in a Hamilton system. A GMA, which has a large strain coefficient, fast response, and strong stability, is coupled to the surface of an SSPS for vibration control. This work particularly considers the coupling effect of vibration–attitude and the complex space environments, such as sunlight pressure and thermal shock, to improve the computation accuracy. Simulation results indicate that GMA has excellent performance in the vibration control of space solar power station. Moreover, GMA can also suppress the attitude changes due to the coupling effect. This study contributes to the stable operation and attitude calibration of the space solar power station, and provides a new reference for the research of dynamics and control of large flexible spacecraft in complex environments. • The coupling effect of vibration-attitude of space solar power station is considered. • A giant magnetostrictive actuator is excellent for the vibration control in aerospace. • Sunlight pressure and thermal shock are regarded as perturbing effects in this work. • A giant magnetostrictive actuator is much improved by increasing the magnetostriction coefficient. • Attitude changes can be indirectly suppressed by giant magnetostrictive actuator. [ABSTRACT FROM AUTHOR]

The internal magnetic field characteristics of giant magnetostrictive actuators have an important influence on their output performance. Aiming at the deficiency of current scholars’ research, based on the electromagnetic theory and finite element method, this paper analyzes the magnetic field intensity on a giant magnetostrictive cylinder by using COMSOL Multiphysics software. Considering the inhomogeneity of magnetic field intensity along the radial direction of giant magnetostrictive cylinders, a new averaging method is introduced to calculate the magnetic field intensity in the axial section of the cylinder. The influence of the magnetic permeability of the displacement conversion mechanism (shell) and the size of the air gap inside the device on the magnetic field intensity of the giant magnetostrictive cylinder are analyzed. The prototype of the actuator is manufactured, and the correctness and accuracy of the simulation data are verified by experiments. In order to make the magnetic field on the cylinder strong and uniform, the displacement conversion mechanism and the shell should be made of low permeability and high permeability materials, respectively, and the air gap size should be reduced as much as possible under the condition of meeting the size requirement of the actuator pre-tightening force applying device.

The deflector by controlling the warhead relative to the missile deflection of a certain angle to change the aerodynamic characteristics and trajectory characteristics of the projectile to achieve the control of the shooting point. Based on this background,a flexible hinge amplifier is designed to amplify the output displacement of the Giant Magnetostrictive Actuator（GMA）. First of all,the maximum output displacement of the amplification mechanism is deduced and calculated. Then,under the given displacement,it is calculated that there is a linear relationship between the input force and the output displacement. The existence of the linear relation is verified by the simulation of the finite element software,compared with the calculated results,it is concluded that the existence of internal reaction force causes additional displacement loss. Finally,combined with the control principle of GMA output force,the relationship between output displacement and GMA output force and total magnetization is deduced.

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Giant magnetostrictive materials (GMMs) have broad application prospects in the field of servo valves, but the giant magnetostrictive actuator (GMA) has problems such as large loss and severe heat generation, which affect the output effect and accuracy. To solve these problems, this paper designs a stacked giant magnetostrictive actuator (SGMA) and analyzes the magnetic circuit and magnetic field distribution of the SGMA. Based on the magnetic field analysis and the Jiles–Atherton model, we analyze the SGMA magnetization model, simplify the traditional model, and give a solution for the simplified model using the Runge–Kutta method. We analyze the eddy current loss of the SGMA, and according to Bessel’s equation and the Kelvin function, we calculate the relationship among eddy current loss, GMM rod radius, and magnetic field frequency. By analyzing the inherent hysteresis of GMMs, a hysteresis loss model of the SGMA is established in this paper. We also calculate the coil impedance and obtain the coil loss model. Based on the loss model, the SGMA cooling system is designed. Based on the above analysis, we design a SGMA prototype, set-up the corresponding experimental platform, and conduct the necessary experiments. The experimental results show that the SGMA responds well to different signals, but as frequency increases, attenuation, deformation, and hysteresis become more pronounced, which verifies the amplitude and phase changes caused by various losses in the theoretical analysis. The experiment also observes the temperature rise of the oil-cooled SGMA at different frequencies, indicating that the cooling system can effectively control the temperature change of the SGMA, which validates the foregoing analysis.

Highlights • A non-hysteresis magnetization model for the GMA was presented using Arctangent function. • Proposed model is suitable to the condition when the maximum magnetization is higher than 20 kA/m. • Proposed model has similar effects to J-A model on computing the amplitude and change rule of the magnetization curve. • The model's accuracy on predicting the output displacement of GMA was verified using experimental data. Abstract Currently, most of the physics-based magnetization models for giant magnetostrictive actuator are complicated in their mathematical models. These complicated models pose considerable challenges for real-time control. Focus on the above issue, we proposed a fitting magnetization model using Arctangent function, as the inverse of the Arctangent function can solve it very quickly. This function was suitable to model the magnetic behavior of giant magnetostrictive actuator serving in an electronic controlled injector or other types of on-off valves. Applicable range of the model was determined through computing the maximum magnetic field. Then the deviations of the proposed fitting model and Jiles-Atherton model under different parameters were studied to verify the computing effects of the model. Then the effectiveness of the fitting model was verified by experimental results. With a high computing precision and a concise form, the proposed model shows great potentials for the real-time control of giant magnetostrictive actuators. [ABSTRACT FROM AUTHOR]

Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press 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.)

A giant magnetostrictive actuator presents advantages such as large strain, high precision, and quick response. It is a hotly debated research topic in the field of micro drivers; however, the nonlinear intrinsic relationship between its output and input signals make it difficult to construct its nonlinear eigen model in the process of its practical application. Therefore, the motivation of this paper is to study the nonlinear magnetic–mechanical coupling characteristics of the giant magnetostrictive actuator, which is driven by free energy hysteresis characteristics. The nonlinear magnetic–mechanical coupling model under the weak form solution is deduced from the basic electromagnetic and mechanical theories, based on the distribution law of the axial magnetic field simulation, carried out to analyze the output displacement characteristics of the giant magnetostrictive actuator under preload. Experimental characterization of the device is also studied in the built experiment setup. Research results show that the experimental results coincide well with the simulation results, which show that the designed magnetic circuit for the giant magnetostrictive actuator is correct, and the coupling model of magnetic and machine of the giant magnetostrictive actuator based on the free energy hysteresis characteristics is reasonable. [ABSTRACT FROM AUTHOR]

The rare-earth giant magnetostrictive material has received considerable attention in recent years and is known as a new type of high efficient magnetic – mechanical conversion material. Its performance is far superior to that of other materials such as piezoelectric ceramic and so on. Giant magnetostrictive actuator has been widely used in precise driving occasions for its excellent performance. The experimental analysis system for giant magnetostrictive material is designed. Several important parameters have been discussed separately by static and dynamic experiment. Further, the nonlinear magnetic hysteresis characteristic is analyzed by theoretical method. The turning machining analysis model is established and the analytical solution is verified by comparison with the test result. The influence of various parameters is discussed at the same time. Obviously, the research results and methods provide a basis for giant magnetostrictive actuator. [ABSTRACT FROM AUTHOR]

This paper focuses on the safety of high-speed trains under strong crosswind conditions. A new active control strategy is proposed based on the adaptive predictive control theory. The new control strategy aims at adjusting the attitudes of a train by controlling the new-type intelligent giant magnetostrictive actuator (GMA). It combined adaptive control with dynamic matrix control; parameters of predictive controller was real-time adjusted by online distinguishing to enhance the robustness of the control algorithm. On this basis, a correction control algorithm is also designed to regulate the parameters of predictive controller based on the step response of a controlled objective. Finally, the simulation results show that the proposed control strategy can adjust the running attitudes of highspeed trains under strong crosswind conditions; they also indicate that the new active control strategy is effective and applicable in improving the safety performance of a train based on a host-target computer technology provided by Matlab/Simulink. [ABSTRACT FROM AUTHOR]

In this study, an integrative giant magnetostrictive material-based electro-hydrostatic actuator (GMEHA) was designed. Firstly, the uniform of magnetic field distribution on giant magnetostrictive material rod was obtained by using finite element method, i.e. the nonuniformity of the axis and radial direction magnetic field intensity were less than 3% and 0.05%, respectively. Secondly, the flow rate model through the reed valve model was established in COMSOL Multiphysics software, and the relevant properties of reed valves were studied. Thirdly, the dynamic mathematical model of GMEHA was systematically established based on the operational principles of the GMEHA, accordingly, and the simulation model of GMEHA was built in Matlab/Simulink. Finally, the model and simulation results were subsequently verified with the experimental data, which indicates the effective output stroke of the designed GMEHA reached 70 mm, and the maximum no-load output flow was 0.85 L/min at approximately 250 Hz with the best working frequency; the blocked force was nearly 120 N. These results demonstrated the accuracy of the theoretical model and provided a foundation for the design and optimization of the GMEHA. [ABSTRACT FROM AUTHOR]

A light and thin underwater large-plate active acoustic structure is developed that satisfies the particular requirements of high pressure resilience, low frequency and high efficiency encountered in underwater work environments. A low-frequency miniaturized active control unit, with a thickness of less than 50 mm, is designed using giant magnetostrictive material (GMM). The noise reduction performance is measured with an active control system based on a multi-channel adaptive filter. The active control system is developed within a LabVIEW environment and can achieve significant levels of noise reduction within time intervals of less than one second achieving absorption coefficients far exceeding 0.8 even under high pressures. The new active-control system incorporates hardware and software components and represents a novel technology for low-frequency underwater noise reduction. [ABSTRACT FROM AUTHOR]

A specific giant magnetostrictive actuator (GMA) is developed for injectors in high-pressure-common-rail system. The magnetic strength, with its axial distribution unevenness considered, is determined by the driving current and axial dimension. Multiple degrees of freedom model of the specific GMA is established based on Jiles-Atherton (J-A) model and vibration theory. The number of degrees of freedom is optimized, and step response is calculated and its state-space model is provided and computed using MATLAB. Steady-state response and frequency response in moderate driving level is achieved and verified by the test results, and load contributed by fluid is regarded as elastic-damping load and the specific response of GMA in this case could be forecast. From the measured result, the proposed multiple degrees of freedom model are amenable to describe the stable response of the specific GMA under low frequency harmonic driving. [ABSTRACT FROM AUTHOR]

A theoretical magnetic field intensity model within giant magnetostrictive material was presented. This model was established just like the reluctance model, while could describe the non-uniform distribution flexibly for its integral form. This model employed magnetic circuit theorem calculating the mean of the magnetic field, while used a normalized function describing the distributing character. The distributing function was determined by Biot--Savart law and relative permeability of the material. The model was validated with the help of the experimental device. At last, the fitting degree of the model with the tested results in predicting the performance of the actuator is researched. [ABSTRACT FROM AUTHOR]

Rock bolts, as a type of reinforcing element, are widely adopted in underground excavations and civil engineering structures. Given the importance of rock bolts, the research outlined in this paper attempts to develop a portable non-destructive evaluation method for assessing the length of installed rock bolts for inspection purposes. Traditionally, piezoelectric elements or hammer impacts were used to perform non-destructive evaluation of rock bolts. However, such methods suffered from many major issues, such as the weak energy generated and the requirement for permanent installation for piezoelectric elements, and the inconsistency of wave generation for hammer impact. In this paper, we proposed a portable device for the non-destructive evaluation of rock bolt conditions based on a giant magnetostrictive (GMS) actuator. The GMS actuator generates enough energy to ensure multiple reflections of the stress waves along the rock bolt and a lead zirconate titantate (PZT) sensor is used to detect the reflected waves. A new integrated procedure that involves correlation analysis, wavelet denoising, and Hilbert transform was proposed to process the multiple reflection signals to determine the length of an installed rock bolt. The experimental results from a lab test and field tests showed that, by analyzing the instant phase of the periodic reflections of the stress wave generated by the GMS transducer, the length of an embedded rock bolt can be accurately determined. [ABSTRACT FROM AUTHOR]

Due to the influence of magnetic hysteresis and energy loss inherent in giant magnetostrictive materials (GMM), output displacement accuracy of giant magnetostrictive actuator (GMA) can not meet the precision and ultra precision machining. Using a GMM rod as the core driving element, a GMA which may be used in the field of precision and ultra precision drive engineering is designed through modular design method. Based on the Armstrong theory and elastic Gibbs free energy theory, a nonlinear magnetostriction model which considers magnetic hysteresis and energy loss characteristics is established. Moreover, the mechanical system differential equation model for GMA is established by utilizing D'Alembert's principle. Experimental results show that the model can preferably predict magnetization property, magnetic potential orientation, energy loss for GMM. It is also able to describe magnetostrictive elongation and output displacement of GMA. Research results will provide a theoretical basis for solving the dynamic magnetic hysteresis, energy loss and working precision for GMA fundamentally. [ABSTRACT FROM AUTHOR]

The ultra-compact electric vehicle has recently experienced increasing popularity for short-distance travel. However, one of the issues with ultra-compact electric vehicles is that although the engine is silent, exterior road and wind noise have a significant impact on the occupant’s comfort in the interior space. We propose an ANC system whereby a kind of small actuator is installed on the roof of an ultra-compact electric vehicle. In this paper, we consider the noise control effects of using a giant magnetostrictive actuator and conduct an experimental study on feed-forward and feedback control systems.

Typical giant magnetostrictive actuator (GMA) cannot meet the requirement of driving a high-speed on-off valve for limitation in bias magnetic field exerted on giant magnetostrictive material. To solve this problem, a novel GMA is designed with zero bias magnetic field. Furthermore, to satisfy the requirement of the displacement direction, a ' T' type transfer rod is joined to convert material's elongating into actuator's shortening. Simultaneously, long responding time of the actuator, especially the rising time of coil current, is also considered in this paper. The transient-state current is modeled based on the equivalent circuit considering parallel resistance of the coil, and from computed result, high opening voltage can be taken to promote responding speed of the actuator, and then an optimized driving voltage wave is presented. At last, with the help of an experimental system, the current model is verified and the driving effect of optimized voltage wave is tested and analyzed. [ABSTRACT FROM AUTHOR]

A giant magnetostrictive actuator is designed with strong bias magnetic field. The influence of the strong bias field is introduced, and the corresponding exciting input signal is selected. Magnetic reluctance estimation, approximate linearity between the strain and magnetic field, and a mass–spring–damper system assumption are employed to analyze the actuator’s displacement with low-frequency signal input. An experimental system is designed, and properties of the proposed actuator are tested. With the help of square wave test, appropriate direction of exciting signal for the magnetostrictive actuator is determined. With the help of sinusoidal wave test, the established model is validated and the relationship between the maximum value of the displacement and of the current is analyzed. With exciting frequency lower than 200 Hz, the errors between the calculating and testing results are within 1.0 m, which validates the model. [ABSTRACT FROM AUTHOR]

In recent years, micro-compact electric vehicles have been developed and actively marketed, and has become popular as a new short-distance transfer mobility tool. While micro-compact electric vehicles do not have generate an engine sound, road and wind noises cause interior noise, and have a large impact on user comfort in the interior space. Recently the use of interior noise reduction by ANC has been used in the automobile industry. In this study, we propose a system whereby a giant magnetostrictive actuator is installed on the front window of a micro-compact electric vehicle to actively cut interface vibration noise, i.e., road noise, transmitted to the interior of the vehicle. In the experiment, we used an enclosure to simulate the interior of a vehicle and investigated the installation position of the giant magnetostrictive actuator to study the vibration characteristics of a window plate. [ABSTRACT FROM AUTHOR]

A novel giant magnetostrictive actuator driving the ball-valve of a high-pressure common-rail injector was designed in this paper. With the help of a special output rod, elongation of the giant magnetostrictive rod was converted to shortening of the actuator. So the actuator could suitable to a normally-closed injector. The traditional series equivalent circuit of the coil in the actuator was modified, and then the displacement model of the actuator was established and solved by a numerical method. The voltage, coil current and displacement of the actuator were acquired by a dedicated measuring system. Then the model was validated under the input voltages using sinusoid, AC square and DC square waveforms. A new driving voltage waveform suitable to the actuator was designed. And then the designed voltage was optimized for short responding time and slight fluctuation of the actuator displacement. The residual displacement caused by the hysteresis of giant magnetostrictive material was also considered. [ABSTRACT FROM AUTHOR]

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Giant magnetostrictive actuator with strong bias magnetic field is designed to control the injector bullet valve opening and closing. The relationship between actuator displacement amplitude and input signal direction is analyzed. And based on the approximate linearity of strain-magnetic field, second-order system model of the actuator displacement is established. Experimental system suitable for the actuator is designed. The experimental results show that, the square voltage amplitude being 12 V, the actuator displacement amplitude is about 17 μm with backward direction signal input while being 1.5 μm under forward direction signal. From the results, the suitable input direction is confirmed to be backward. With exciting frequncy lower than 200 Hz, the error between the model and experimental result is less than 1.7 μm. So the model is validated under the low-frequency signal input. The testing displacement-voltage curves are approximately straight lines. But due to the biased position, the line slope and the displacement-voltage linearity change as the input voltage changes. [ABSTRACT FROM AUTHOR]

A typical giant magnetostrictive actuator (GMA) expands a magnetostrictive rod to generate strain by varying the current in the coil that surrounds the magnetostrictive rod. The heat generated by the current deteriorates the GMA performance. In particular, a constant current in the coil is required to produce the desired magnetic field when an output strain should be maintained. The GMA does not produce any mechanical power in this condition, but constant power is being consumed by the excitation coil. This paper presents a new type of motor-driven GMA (MDGMA), which works in a coil-free driven manner. The magnetic field in the iron–gallium alloy (Galfenol), which is a type of magnetostrictive material, is periodically altered by rotating the permanent magnets instead of varying the coil current in the traditional GMA. The proposed MDGMA not only achieves continuous adjustment of the output strain, but can also maintain a constant output strain without consuming any power. In addition, the coil-free design releases the new MDGMA from the heat generated by the excitation coil, which allows the MDGMA to work more stably. [ABSTRACT FROM AUTHOR]

This paper presents an induced voltage linear extraction method for disturbing force self-sensing in the application of giant magnetostrictive actuators (GMAs). In this method, a Kelvin bridge combined with an active device is constructed instead of a conventional Wheatstone bridge for extraction of the induced voltage, and an additional GMA is adopted as a reference actuator in the self-sensing circuit in order to balance the circuit bridge. The linear fitting of the measurement data is done according to the linear relationship between the disturbing forces and the integral of the induced voltage. The experimental results confirm the good performance of the proposed method, and the self-sensitivity of the disturbing forces is better than 2.0 (mV·s)/N.