GIANT MAGNETOSTRICTIVE ACTUATOR IN SERVO VALVE AND MICRO PIPE ROBOT

Performance of giant magnetostrictive material (GMM) is introduced. Principleof work, basic structure and key techniques of giant magnetostrictive actuator (GMA) are analyzed.Its dynamic models of magneto-mechanical coupling are established. The structure and principle ofthe pneumatic servo valve and the micro pipe robot with new homemade GMM are presented. Theexperiment is carried out under typical working conditions. The experiment results show that the GMMpneumatic servo valve has wide pressure control characteristics, good linearity, and fast responsespeed. The movement principles of the GMM robot system are reliably feasible and its maximal movingspeed is about 8 mm/s. It is preferable to the driving frequency of the robot within 100 approx 300Hz.

Bifurcation and chaos characteristics of hysteresis vibration system of giant magnetostrictive actuator

Chaotic motion and quasi-periodic motion are two common forms of instability in the giant magnetostrictive actuator(GMA).Therefore,in the present study we intend to investigate the influences of the system damping coefficient,system stiffness coefficient,disc spring cubic stiffness factor,and the excitation force and frequency on the output stability and the hysteresis vibration of the GMA.In this regard,the nonlinear piezomagnetic equation,Jiles-Atherton hysteresis model,quadratic domain rotation model,and the GMA structural dynamics are used to establish the mathematical model of the hysteresis vibration system of the GMA.Moreover,the multi-scale method and the singularity theory are used to determine the eo-dimensional two-bifurcation characteristics of the system.Then,the output response of the system is simulated to determine the variation range of each parameter when chaos is imposed.Finally,the fourth-order Runge-Kutta method is used to obtain the time domain waveform,phase portrait and Poincare mapping diagrams of the system.Subsequently,the obtained three graphs are analyzed.The obtained results show that when the system output is stable,the variation range of each parameter can be determined.Moreover,the stability interval of system damping coefficient,system stiffness coefficient,and the coefficient of the cubic stiffness term of the disc spring are obtained.Furthermore,the stability interval of the exciting force and the excitation frequency are determined.

Structure design and characteristics analysis of a cylindrical giant magnetostrictive actuator for ball screw preload

In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator （CGMA）, which is the core component of the preload system, is developed using giant magnetostrictive material （GMM） with a hole. The pretightening force of the CGMA is determined by testing. And the magnetic circuit analysis method is introduced to calculate magnetic field intensity of the actuator with a ball screw shaft. To suppress the thermal effects on the magnetostrictive outputs, an oil cooling method which can directly cool the heat source is adopted. A CGMA test platform is established and the static and dynamic output characteristics are respectively studied. The experimental results indicate that the CGMA has good linearity and no double-frequency effect under the bias magnetic field and the output accuracy of the CGMA is significantly improved with cooling measures. Although the output decreased with screw shaft through the actuator, the performance of CGMA meets the design requirements for ball screw preload with output displacement more than 26 μm and force up to 6200 N. The development of a CGMA will provide a new approach for automatic adjustment of double-nut ball screw preload.

DEVELOPMENT OF THE CONTROL METHODOLOGY OF THE GIANT MAGNETOSTRICTIVE ACTUATOR BASED ON MAGNETIC FLUX DENSITY

According to the principle of the magnetostriction generating mechanism, thecontrol model of giant magnetostriction material based on magnetic field and the control method withmagnetic flux density are developed. Furthermore, this control method is used to develop a giantmagnetostrictive micro-displacement actuator (GMA) and its driving system. Two control methods whosecontrol variables are current intensity and magnetic flux density are compared with each other byexperimental studies. Finally, effective methods on improving the linearity and control precision ofmicro-displacement actuator and reducing the hysteresis based on the controlling magnetic fluxdensity are obtained.

Research on Giant Magnetostrictive Actuator for Turning Vibration Control

Magnetostriction is a phenomenon in which a magneti c field is used to produce a change in size of some materials. This property has b een known in elements such as nickel, iron and cobalt. Because the rare-ear th alloy Terfenol-D can offer much larger strains than nickel, iron, cobalt, an d other smart materials such as piezoelectric materials, it is called giant magn etostrictive material. Making use of the giant magnetostrictive material, the gi ant magnetostrictive actuator has higher bandwidth and rapider response than oth er actuators. So it is widely used in active vibration control, especially in lo w frequency stage. In this paper, a turning vibration control system is develope d. The system has an actuator clamped in a flexor that is rigid in the feed and main cutting force directions, yet is flexible in the radial direction. The stru cture of the giant magnetostrictive actuator is developed after magnetic circuit and some structure parameter are calculated. According to the turning frequency , the transient and stable-state output of the giant magnetostrictive actuator is measured. The test result demonstrated that the actuator responses the input rapidly, and the actuator has perfect stable-state and transient output charact eristic. The characteristic includes the stable-state output linearity, repeata bility and transient delay between output displacement and input current.

Experimental Research on Output Performances of Giant Magnetostrictive Actuator

The paper introduces the performances of magnetostrictive actuators and its applications,discusses the design methods for the structure and internal magnetic circuit of a giant magnetostrictive actuator,and makes tests on the output displacement and force characteristics for an actuator using homemade magnetostrictive material.The experimental result shows that the actuator has satisfactory output precisions and ranges in transient and stable states,and can be used in low-frequency vibration control system of precise equipment.

Theory and experiment of observer based magnetostrictive self-sensing actuator

Giant magnetostrictive actuators (GMAs) often work in a close-loop feedback system. This system needs independent sensors which may be difficult to be fixed, besides, excessive sensors may cause more unpredicted problems in a large system. This paper aims to develop a self-sensing GMA. An observer based on piezomagnetic equations is constructed to estimate the stress and strain of the magnetostrictive material. The observer based self-sensing approach depends on the facts that the magnetic field is controllable and that the magnetic induction is measurable. Aiming at the nonlinear hysteresis in magnetization, a hys- teresis compensation observer based on Preisach model is developed. Experiment verified the availability of the observer approach, and the hysteresis compensation observer has higher tracking precision than linear observer for dynamic force sensing.

Magnetostrictive and Kinematic Model Considering the Dynamic Hysteresis and Energy Loss for GMA

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.

基于因素趋势法的GMA磁场研究和仿真分析

为增强超磁致伸缩驱动器(GMA)输出特性,提高超磁致伸缩材料(GMM)棒在磁场下的磁致伸缩性能,根据安培环路定律、基尔霍夫定律、磁通的连续性定律建立GMA磁路模型,推导出GMM棒中心线磁场强度和均匀率与GMA内各结构参数的关系式。在Ansys Maxwell中建立简化的二维平面模型,依据L_(25)(5^(5))正交试验仿真分析,做极差分析、绘制因素趋势图、回归分析和规划求解,得出GMA内各结构参数对最大磁场强度和均匀率的影响。结果表明:GMM棒几何参数、GMA组件材料属性、线圈匝数和电流参数在工程设计约束下,影响GMM棒最大磁场强度和均匀率的主要因素为导磁片半径、导磁片厚度和驱动线圈长度。在多因素多目标决策,采用目标规划法,得到GMA最大磁场强度为40.22 kA/m,均匀率为95.17%。

分数阶阻尼GMA系统主共振振动特性研究

为更精确表达超磁致伸缩致动器(GMA)的动力学特性,研究了含分数阶阻尼的GMA磁滞非线性系统的受迫振动。利用分数阶微积分描述GMA磁滞非线性系统的阻尼力,建立具有分数阶阻尼的GMA动力学方程;利用平均法得到GMA系统的近似解析解,对含有分数阶阻尼的GMA系统进行主共振分析,得到系统稳定时的条件和幅频响应方程。使用MATLAB软件分析分数阶阻尼力对系统动力学的影响,对系统主共振幅频响应的解析解与数值解进行比较,发现两者符合程度较高;详细分析分数阶阻尼对GMA磁滞非线性系统主共振幅频响应的影响,相比于整数阶系统得到更为丰富的非线性现象,对控制和预测系统的输出响应具有重要意义。

基于GMA的列车主动悬挂系统垂向振动分析

针对列车被动悬挂系统对列车减振效果不明显的问题,提出一种超磁致伸缩作动器(Giant Magnetostrictive Actuator, GMA)用于主动悬挂系统中的方法。基于列车主动振动特性和超磁致伸缩作动器的磁致伸缩工作机理,搭建GMA为作动器的主动悬挂系统模型,通过MATLAB/Simulink仿真软件得到车体垂向振动响应。仿真结果表明,基于超磁致伸缩作动器的列车主动悬挂系统,与被动悬挂系统相比,抑制了列车垂向振动,列车垂向平稳性指标优化了12.62%,提高了列车运行品质。

超磁致伸缩致动器非线性动力学的分数阶时滞反馈控制

设计了一种分数阶时滞反馈控制器,用于控制单自由度的超磁致伸缩致动器(GMA)的非线性动态响应。考虑到预压碟形弹簧机构引入的几何非线性因素影响,建立了GMA系统的非线性数学模型。利用平均法求解系统在含分数阶时滞反馈控制策略下主共振的幅频响应方程,根据Routh-Hurwitz准则得到系统的稳定性条件。通过数值模拟研究GMA系统中关键结构参数对幅频响应特性的影响,以及主共振峰值和系统稳定性随每个时滞反馈参数变化的特性规律;通过分岔图和Lyapunov指数图得到外激励幅值对系统混沌运动的影响;最后调节时滞反馈增益和分数阶次抑制系统的混沌运动。结果表明,时滞反馈增益和分数阶次能够有效抑制系统的主共振峰值和不稳定区域,可以将系统响应从混沌运动调整为稳定的周期运动,提高系统的稳定性。

微型超磁致伸缩驱动器混沌特性分析

混沌运动和准周期运动是超磁致伸缩驱动器中两种常见的不稳定性形式。本文用压磁方程和结构动力学建立了GMA系统方程,无量纲化处理后对其混沌特性进行分析,对输出响应进行仿真。用4阶龙格—库塔法求解近似解析解,并绘制系统响应随无量纲激振力f_(φ)和激励频率Ω变化的分岔图和Lyapunov指数图,以及相应的时域波形、相轨迹图、幅值谱图和Poincaré图。结果表明:激振力在区间(0,1.56)和(3.41,5)内有周期性,激励频率在区间(0,1.07)、(1.11,1.8)和(2.11,3)内有周期性。调整激励力和频率可避免混沌运动发生,从而提高驱动器的工作稳定性。

超磁致伸缩换能器磁场强度建模与线圈优化分析

磁场强度是决定换能器性能的关键变量,为了提高超磁致伸缩换能器(GMA)的磁场强度和输出位移,本文提出了一种新型的弓张式发音振子结构,用COMSOL软件建立二维模型,得到超磁致伸缩材料(GMM)棒内部磁场分布情况。由于弓结构内部空间受限,对激励线圈进行优化,讨论了导线经验模型、静态电阻和电感模型的适用性,建立了线圈的平均磁场模型,以线径为决策变量,计算了正弦响应下不同线径的振幅比和相位滞后。结果表明:该模型在计算电阻和电感时的相对误差分别小于5.3%和4.1%。在预测正弦响应时,计算振幅比的误差低于6.6%(在大多数条件下低于1.8%),计算滞后相位的误差低于3.4%。较宽的导线直径对提高磁场振幅有较大的帮助,但对磁场的相位滞后性影响很小。

超磁致伸缩力传感执行器磁路优化设计与分析

以超磁致伸缩力传感执行器为研究对象,基于磁致伸缩与涡流损耗理论,应用COMSOL有限元软件进行磁场分析,系统地研究了导磁体参数对磁通密度与涡流的影响规律。为增大磁通密度、减小涡流损耗,以超磁致伸缩棒中轴线上磁通密度均匀度为评价标准,优化了导磁体参数,并将导磁体分区绝缘。静、动态磁场下与未优化时实验结果进行对比,结果表明:静磁场中优化后的磁通密度均值提升了0.0161T,均匀度提升了4.5%;动态磁场中,分区绝缘可有效减少涡流损耗,优化后的力传感器灵敏度提升了5.76%。

Experimental characterization and modeling of stress-dependent hysteresis of a giant magnetostrictive actuator

The hysteresis nonlinearity of giant magnetostrictive actuator(GMA) is stress-dependent.In this paper,laboratory experiments were performed to characterize the stress-dependent hysteresis properties of a GMA under different compressive stresses ranging from ?11.3 MPa to ?24.3 MPa and harmonic current excitation with amplitudes from 0.6 A to 1.2 A.The experimental results showed that remarkable changes in peak-peak displacement responses,hysteresis loop width and hysteresis loss occurred with the increasing of compressive stress;no significant changes in coercive current were observed.Based on the analysis of experimental data and discussion of the influences of the weights of Modified Prandtl-Ishlinskii(MPI) on the characteristics of hysteresis loops,a stress-dependent Prandtl-Ishlinskii(SDPI) model was proposed by extending the MPI model to describe the effects of compressive stress,in which the weights of deadzone operators are extended as function of compressive stress.Good agreements were obtained between the model simulation results and the experimental data.Additional model validations were given by the performances of tracking control experiments with an inverse feedforward controller.The experimental results have clearly shown that the inverse SDPI is effective for compensating stress-dependent hysteresis including major and minor loops.

Robust intelligent modeling for giant magnetostrictive actuators with rate-dependent hysteresis

Purpose–This paper proposes a robust modeling method of a giant magnetostrictive actuator which has a rate-dependent nonlinear property.Design/methodology/approach–It is known in statistics that the Least Wilcoxon learning method developed using Wilcoxon norm is robust against outliers.Thus,it is used in the paper to determine the consequence parameters of the fuzzy rules to reduce the sensitiveness to the outliers in the input-output data.The proposed method partitions the input space adaptively according to the distribution of samples and the partition is irrelative to the dimension of the input data set.Findings–The proposed modeling method can effectively construct a unique dynamic model that describes the rate-dependent hysteresis in a given frequency range with respect to different single-frequency and multi-frequency input signals no matter whether there exist outliers in the training set or not.Simulation results demonstrate that the proposed method is effective and insensitive against the outliers.Originality/value–The main contributions of this paper are:first,an intelligent modeling method is proposed to deal with the rate-dependent hysteresis presented in the giant magnetostrictive actuator and the modeling precision can fulfill the requirement of engineering,such as the online modeling issue in the active vibration control;and second,the proposed method can handle the outliers in the input-output data effectively.

基于Preisach修正模型的GMA前馈补偿研究

超磁致伸缩驱动器(GMA)的磁滞建模与非线性补偿是实现GMA高精度定位的基础。根据GMA的特点,提出了GMA的磁滞Preisach修正模型建模与非线性补偿方法。设计制作了一台GMA样机,对其主磁滞回线和一阶折返曲线进行了精密测量,基于实验数据建立了驱动器的Preisach磁滞修正模型。为了避免对Preisach算子求逆,提出了一种以主磁滞回线升程为基准的输入校正迭代算法,并以此设计了驱动器的前馈补偿器,实验表明,提出的GMA前馈补偿方法具有较高的精度,其定位误差不超过1%。

GMA在脉冲喷射开关阀中的应用

通过分析脉冲喷射开关阀的工作性能,提出致动器是决定脉冲喷射开关阀特性的关键因素.对比3种致动器的性能参数,指出GMA更适合脉冲喷射开关阀的工作要求.GMA的性能分析和仿真结果给出了在脉冲喷射开关阀中工作的GMA的静、动态特性.脉冲喷射开关阀单脉冲流量实验曲线表明:脉冲喷射开关阀的单脉冲流量随励磁电流的变化规律与GMA的磁致伸缩曲线特性相似,在GMA的磁致伸缩曲线的线性区即可满足单脉冲喷射流量要求.动态实验中,脉冲喷射开关阀的阀芯位移阶跃响应上升时间只有0.81 ms,远远满足脉冲喷射开关阀应用的工作频率要求.

基于GMA喷嘴挡板伺服阀的动态特性

提出基于GMA喷嘴挡板伺服阀的新结构,研制了GMM电-机械转换器及其喷嘴挡板伺服阀,分析其结构特点与需要解决的关键技术,建立动态数学模型。构建基于GMA喷嘴挡板伺服阀动态特性的试验系统,试验研究GMA喷嘴挡板伺服阀的阶跃和幅频响应特性,试验测得其阶跃响应上升时间为1 ms、幅频宽达680 Hz;将试验结果与仿真结果进行对比分析,两者基本吻合,论证动态数学模型的正确性。研究结果表明,用GMM设计新型电-机械转换器,可提高喷嘴挡板阀乃至整个电液伺服系统的频响和精度。