基于电磁作动器的SPWM振动主动控制技术研究

开发了一种采用电磁作动器的SPWM振动主动控制系统。简单介绍了电磁作动器的数学模型，通过仿真分析与试验分析了解了作动器的作动特性。阐述了SPWM的调制原理与频谱分析。对某中型货车发动机振动主动控制系统进行了控制规律研究，并应用单片机技术对控制系统进行了减振试验验证。结果表明发动机振动衰减明显，该振动主动控制系统的设计是可行的。     

新型高效电磁反力作动器的设计

针对发动机振动主动控制系统设计了一种高性能电磁反力作动器。首先简单介绍了作动器的设计要求以及结构原理,接着对作动器的磁场进行了近似计算,并将作动器的力传递模型简化为单自由度振动系统,计算了作动器的作动力。最后通过Simulink软件对其作动力进行了仿真,并以正弦信号输入对作动器的作动力进行了性能试验。结果表明作动力大,作动器性能良好,这对发动机振动主动控制系统的实现以及开展其他主动控制系统的研究具有非常重要的意义。     

新型高效电磁驱动反力作动器的设计及特性研究

设计了一种新型高效电磁驱动反力作动器，进行了作动器的磁场计算，利用Ansys软件对其弹簧刚度进行了分析。建立了作动器的力传递模型，通过Matlab软件对其力传递特性进行了仿真分析。以正弦信号输入对作动器的作动特性进行了试验，结果表明作动力大，作动器性能良好，可以很好适用于各种振动系统的主动振动控制。     

振动主动控制中电磁作动器动态特性的研究

分析了电磁作动器的动态特性及其对振动主动控制系统振动传递率的影响。振动传递率不仅受作动器动态特性的影响,而且还与反馈变量的选取有关。因此,在实际控制系统中应选择绝对位移、速度、加速度及加加速、绝对位移的积分和相对位移、速度、加速度及加加速度、相对位移的积分的不同组合作为反馈变量,以期取得良好的隔振效果。     

主动控制中作动器非线性谐频的控制

采用主动隔振系统,能有效地控制低频线谱振动。在常规的作动器中,虽然可以有效地降低基频的振动;但二次谐波处产生的附加能量会影响隔振效果。通过理论分析与试验,研究了振动主动控制系统中电磁作动器的非线性现象,分析了进行低频线谱振动控制时电磁作动器在二次谐频处产生额外能量的原因,提出用谐波发生器自适应补偿作动器非线性现象的方法,结合前馈Fx LMS算法进行主动控制的试验表明,系统可得到较理想的控制效果。     

主动控制式电磁液压悬置隔振性能研究

在原有液压悬置的基础上,提出一种利用电磁作动器为主动控制元件的主动悬置,研究了电磁作动器的频率特性,并建立了该悬置系统的力学及数学模型.选择滤波后的x-LMS算法作为控制算法,利用Matlab软件,仿真分析了该悬置的隔振性能.结果表明：在不同转速下,主动悬置系统都能使传递到车身的振动力大为减弱,在2秒钟时间内就降到无主动控制时的10%以下,说明采用主动控制后的悬置能有效隔离发动机的振动.     

磁控形状记忆合金作动器设计及其控制效果

为探索磁控形状记忆合金（MSMA）可作为一种在振动控制领域中可推荐的新型智能驱动材料,在对其力学性能的研究中,给出其输出控制力的变化规律,继后自行研制MSMA作动器,确定MSMA材料的外形尺寸、变形恢复装置、磁路设计等重要的因素。建立平面直径为80m单层球面网壳结构,按照三种方案设置基于MSMA作动器的控制元件,并应用反应谱计算了竖向地震荷载作用下的响应,通过和无控结构的响应进行对比分析取得MSMA的控制效果。结果表明,MSMA主动控制元件对大跨网壳结构的振动控制效果很明显,是一种理想的智能驱动材料,有着广阔的应用前景。     

砧骨激励式人工中耳作动器的设计及实验

为治疗感音神经性听力损伤,设计的中耳植入式助听器,近年来已成为国内外研究的热点。提出一种砧骨激励式中耳植入助听装置,设计时综合考虑植入位置、空间、手术过程等,并对加工出的装置进行了相关实验。该装置采用压电式作动器,结构简单,作动器产生的力能够高效地传送至听骨链。在设计过程中使用有限单元法（FEM）对装置的共振频率和输出位移进行预估,仿真及实验结果说明该作动器具有良好的动态响应特性,谐波失真度小于1 %,在6.9 Vrms电压驱动下能够提供相当于鼓膜处90 dB SPL激励的效果,可以激励镫骨产生足够的位移以补偿听力损失,是一款有效的助听装置。     

一种电磁作动器的有限元分析与测试

对一种电磁作动器进行有限元建模与模态分析,计算得到了作动器的动态特征参数,通过改变弹簧的几何参数使作动器的一阶固有频率低于20Hz,而输出力在20—500Hz内无共振峰,有利于进行振动控制。实测的频率响应表明有限元的分析结果是合理的,作动器的频率响应在20—3000Hz内没有共振峰,满足性能要求。     

基于作动力反馈控制的电磁反力式混合型主动悬架

提出一种同时含有被动和主动结构的新型汽车主动悬架,与现有主动悬架的最大不同点在于由电磁反力作动器产生的主动控制力仅作用于汽车非悬挂质量.首先,探讨电磁反力作动器的被动特性和以作动器作动力为PI反馈控制量的主动特性,作动器的主动特性显示较好的"天棚"阻尼特性.其次,建立对作动器作动力进行反馈控制的混合型主动悬架1/4车辆模型,并进行特性仿真试验.结果表明,采用作动器作动力进行反馈控制的新型主动悬架效果较好,能够同时改善悬架系统车轮环节共振高频段的平顺性、车轮接地性和减少悬架弹簧的变形.     

电磁辅助压电致动器设计开发与性能测试研究

传统的压电致动器,受限于压电致动的小行程,通常只能测量较小的范围。研发了一种电磁辅助压电致动器,同时具备电磁式致动器长行程与压电式致动器高分辨率的特点,该致动器包含可动件、导引槽、挠性件、电磁铁、压电元件以及控制电路。首先调整挠性可调预压装置并设定电磁铁电流,使得电磁致动力处于最大静摩擦力与动摩擦力之间;再利用压电组件所产生的微震动,控制可动件与导引槽之间的接触情况在静摩擦与动摩擦之间切换,从而完成长行程(10mm)且高分辨率(1.5μm)的往复运动。实验结果表明该致动器具备出色的定位能力。     

Analytical Force Determination in an Electromagnetic Actuator

We present an original analytical determination of the force acting on the moving coil in an electromagnetic actuator. The actuator magnetic field is solved analytically by Schwarz-Christoffel (SC) mapping. The SC integral is solved analytically using the elliptic functions. We verified the results by finite-element methods.      

一种地磁传感器对电磁舵机的抗干扰方法

为了消除电磁舵机对基于地磁传感器的滚转角检测系统的干扰,根据电磁舵机工作时交替产生方向基本相反的干扰磁场的特点,以干扰较弱的方向作为地磁传感器的测量方向,并采用数字滤波器抑制电磁舵机对地磁传感器的干扰.设计了四阶IIR巴特沃斯低通滤波器,提出了预装载延时相位的补偿方法,并计算了相位装载值曲线.实验表明,IIR巴特沃斯低通滤波器能够有效地减小电磁舵机对地磁传感器的干扰,并且预装载延时相位补偿能够消除信号延时的影响,保证基于地磁传感器的滚转角检测系统工作的可靠性和准确性.     

新型纳米级微位移致动器的设计

磁致伸缩型微位移致动器通常采用多晶或孪晶结构材料作为驱动单元 ,由于晶界和孪晶界对畴壁的移动具有阻碍作用 ,其低场下的位移输出较小 ,调控精度受到较大影响。采用Tb Dy Fe单晶材料可以有效解决这一问题 ,本文介绍了采用这一单晶材料设计的新型高精度微位移致动器以及致动器的结构和数控电源     

High-Fidelity Magnetic Equivalent Circuit Model for an Axisymmetric Electromagnetic Actuator

A computationally inexpensive magnetic equivalent circuit (MEC) improves axisymmetric electromagnet design and modeling tools by accurately capturing fringing and leakage effects. Lumped parameter MEC models are typically less accurate for modeling electromagnetic devices than distributed parameter finite-element models (FEMs). However, MEC models require significantly less computational time to solve than FEMs and therefore lend themselves to applications where solution time is critical, such as in optimization routines, dynamic simulation, or preliminary design. This paper describes how fringing permeances in axisymmetric electromagnetic devices can be derived and then included in a MEC model. Including fringing field effects significantly decreases error in the MEC model, creating a more accurate, or high fidelity, magnetic equivalent circuit (HFMEC). Eighty-nine electromagnets with unique geometries, coil currents, and materials were modeled with MEC, HFMEC, and FEM methods. The axisymmetric HFMEC developed in this work had 67% less average force error and 88% less average flux error compared to traditional MEC results while still being computationally inexpensive to solve.      

Hands-on Demonstrations: An Alternative to Full Scale Lab Experiments

Short demonstrations of basic fluid mechanics principles were developed for use in 50 minute seminar sessions, led by graduate student TA's. These have provided structured training for our TA's, lightened the load on our undergraduate lab facilities, and provided our students with visual, active learning opportunities. The demonstrations and handouts were developed by an undergraduate student as a summer project, and expanded on by successive TA's. The response from the students is best illustrated by the increase in seminar attendance from 30% to over 80%.     

雷达天线罩技术及其电性能研究综述

综述了雷达天线罩技术的现状和发展趋势,介绍了雷达天线罩的材料(包括基体材料、增强材料和夹芯材料)、罩壁结构以及成型工艺,并且从雷达天线罩的透波特性和辐射特性两个方面详细介绍了雷达天线罩电性能研究分析方法,为雷达天线罩的设计与制造奠定了基础.     

An Alternative Formation Theory of Beat Applied to the Pendelloesung Fringe and Proposed Confirmatory Experiments

An alternative theory of beat, in which a variation of the intensity of a composite wave is formed from definite distinct waves of which more than two have different frequencies is constructed. It is applied to Pendelloesung beat (hereafter, abbreviated as PB) as an apt example. PB has been observed only in some light elements (below atomic number 32) by using rather hard X-rays up to 60 keV and above the room temperatures. These observations for the formation of PB support the view that the recoil energy loss plays the essentially important role in beat production by the superposition of the photons with the reduction of the momentum. The Bragg law for the reduction of the momentum by the recoil is derived based upon the corpuscular character of the light and the principle of the equipartition of the recoil energy over all the atoms in the crystal. The application of Braggs law, to the superposition of the expected value of the even or odd time multi-reflex photons (taken by the binomial distribution as stochastic events) forms two types of the transmitted or diffracted PB, respectively. The law predicts two types of prominently positive projecting peaks at half wave at even multiples of , and plus or minus projecting peaks at odd times of , according to the multiplicity factor of the reflection, exist as pulsations of bare PB from AM by cosec t in the basic bare envelope curve. It turns out that the AM effect of the binomial distribution on bare PB makes all of the peaks contract as if erased, and makes the intense collimated photon flux follow the Borrmann effect. It is proposed this review can be confirmed experimentally by testing the prediction that the integrated reflection intensity of PB fades into quantum PB as a limit near 0 K by a reduction of the recoil reflections due to the enhancement of the crystal rigidity with decreasing temperature.