高精度稳定平台伺服控制系统仿真实现

为满足稳定平台快速隔离扰动、稳定视轴的要求,通过优化控制结构和控制算法改善系统控制性能。在速度闭环控制的基础上,引入电流内环,提高直流力矩电机的力矩控制精度;采用串联超前滞后校正装置提高系统的隔离度和稳定裕度;利用模糊控制器在线整定PID控制器参数,提高系统动态性能。Simulink仿真表明,系统在常值力矩、周期性力矩及周期性角速率干扰下隔离扰动,具有响应速度快、隔离度好、稳定性高等特点。     

基于钝化微分的压电微动平台PID控制

为避免压电微动平台在工作过程中受到扰动或冲击,采用改进比例、积分、微分(PID)控制器对其进行控制。首先,在平台的PID控制器中引入低通滤波器,以降低微分环节对扰动或冲击的敏感性(即使微分环节对扰动或冲击产生钝化效应),进而设计出了压电微动平台的改进PID控制器;接着,基于所搭建的压电微动平台位移测量系统,实验验证了所设计的钝化微分PID控制器的效果。实验结果表明,在钝化微分PID控制作用下,平台具有较快的响应,达到5μm阶跃目标的响应时间为0.3s,无超调;平台的定位误差显著减小,在跟踪最大值为15.25μm的变幅值三角波时,定位误差中线由无控制时的-0.7～1.2μm减小为-0.1～0.1μm。     

卡尔曼滤波器在抑制力矩扰动中的应用

在光电稳定平台中,摩擦力矩以及探测器制冷机扰动力矩都是影响平台稳定精度的主要扰动源之一。为了克服经典控制方法对机载光电稳定平台探测器制冷机扰动力矩和轴系摩擦力矩抑制能力的不足,在机载光电稳定平台中引入卡尔曼滤波器算法,其作用在于用递推算法将系统及随机测量噪声滤掉。仿真结果表明,采用此方法可以有效抑制轴系力矩扰动。与普通PID 校正算法相比,采用卡尔曼滤波器闭环校正算法的调速精度由40%提高到优于1%。达到了提高稳定精度,克服噪声干扰的目的。     

半捷联导引头光轴稳定性

为研究半捷联导引头光轴稳定性,对影响半捷联导引头光轴稳定的因素进行了分析。通过对半捷联稳定原理和传统速率陀螺稳定原理的分析和比较,揭示了半捷联稳定的实质。根据半捷联稳定方式下平台框架的惯性空间角速度表达式,分析了影响半捷联稳定的主要因素。针对影响半捷联稳定的弹体扰动和扰动力矩,采用了匹配滤波和扰动观测器的方法提高系统稳定精度。数值仿真结果表明,匹配滤波的方法有效地减小了弹体扰动对系统稳定的影响,平台对弹体扰动的解耦精度在1 Hz时提高了38 dB;扰动观测器有效抑制了扰动力矩对系统稳定的影响;采用高精度、低噪声的传感器是减小测速噪声对系统稳定影响的关键。综合仿真结果显示,在对3个主要因素补偿后,系统的稳定误差减小了近94%。     

一种双模糊控制器的设计实现

在工程实际中,很多被控对象具有时变、非线性的特点,用常规的控制方法难以进行控制或者控制效果不好,为了对这类实际系统进行有效地控制,本文基于模糊控制器的基础上,设计实现了一种双模糊控制器,根据实际系统输出信号的误差大小利用两个模糊控制器分别进行控制,以改善系统的快速性和消除误差。从仿真结果来看,和常规PID控制及普通模糊控制相比,双模糊控制器有效地减小了系统稳态误差,响应时间、超调量、稳定时间等性能均优于传统的PID控制和模糊控制。     

机载光电稳定平台滑模自抗扰控制方法研究

针对机载光电稳定平台受扰动影响而导致的视轴稳定精度降低问题,在对线性扩张状态观测器(LESO)进行扰动估计分析及带宽受限分析的基础上,对快速幂次趋近进行了修正,进而提出了一种基于快速幂次趋近律的滑模自抗扰控制器,并进行了基于Lyapunov方法的系统稳定性分析。仿真结果表明,在扰动及参数摄动下,相较于传统滑模控制器和PID而言,使用新型控制器设计的系统具备更高的稳定精度,且抖振抑制效果显著;与趋近律未修正时的控制器相比,新型控制器能使系统维持高精度输出,另外,新型控制器的设计几乎不依赖系统模型信息。故所提方法能提高机载光电稳定平台控制系统的性能。     

一种静不稳定无人机快速跃升与俯冲机动控制器设计

针对无人机在快速跃升与俯冲机动中存在的气动耦合、操纵耦合与不确定扰动,以及由于静不稳定性而造成的不稳定俯仰力矩等问题,提出了一种新的鲁棒模型参考自适应非线性逆控制器。首先,通过基于状态反馈的非线性逆控制完成多通道之间的解耦;然后,依据解耦后的线性闭环系统设计鲁棒模型参考自适应控制器,其主要作用是对非线性逆误差与不稳定俯仰力矩进行补偿,并对不确定扰动进行抑制,从而保证无人机在整个快速机动飞行中的稳定性。通过非线性仿真验证了该控制方法在快速跃升与俯冲纵向机动控制中的有效性与可靠性,并与典型的鲁棒伺服LQR最优控制器对比,说明了该控制器的解耦性能以及对于不确定扰动的抑制作用。     

半捷联导引头混合自抗扰控制系统设计

为了使半捷联导引头在干扰力矩和刻度尺误差引起的耦合干扰及其他不确定干扰下仍具有很强的鲁棒性,提出了伺服系统混合自抗扰控制（Active Disturbance Rejection Control,ADRC）方案。首先,建立了导引头半捷联稳定平台数学模型;其次,设计了半捷联导引头稳定平台混合自抗扰控制系统,通过对自抗扰稳定回路频带特性进行研究,分析了控制器参数对控制性能的影响,给出了控制参数设计原则;最后,对混合自抗扰控制方案进行了数字仿真验证。仿真结果表明:相比于传统控制器,混合自抗扰控制器能获得更好的控制精度,能有效克服干扰力矩和刻度尺误差对导引头的影响,在典型弹体频率2 Hz处隔离度幅值比传统控制器最多能降低约67.9%。研究成结果可为半捷联导引头稳定控制系统的设计提供指导。     

内模PID控制器在无刷直流电机调速系统中的应用

针对无刷直流电机中传统PID控制器参数调节复杂、对环境适应能力较弱等问题,在分析内模控制与经典PID控制的内部对应关系的基础上,综合其优点,设计采用了一种基于内部模型的PID控制器（简称IMC-PID）对无刷直流电机进行调速。在建立对象理论模型的基础上,通过对控制器在线仿真比较表明：针对本设计对象,基于内部模型的PID控制器不论在系统阶跃响应或是扰动跟踪等控制效果上都能到达经典PID控制的要求,同时还降低了参数设计的复杂性和随机性。     

陀螺稳定平台速度环的离散自抗扰控制

针对陀螺稳定平台在高精度定位下的控制精度受到速度环电机在低速运动时非线性摩擦力影响的问题,文章设计了一种改进策略的自抗扰控制器,将原系统中的非线性摩擦力与电机不同转向时的模型误差统一视为系统扰动,采用扩张状态观测器对这个扰动进行估计,前馈到控制量中进行校正。理论分析了一阶离散系统上扩张状态观测器的推导过程和稳定性条件,并采用遗传算法工具箱对针对平台所设计的扩张状态观测器的参数进行辨识。在仿真实验中,我们首先分析了所设计的扩张状态观测器的开环性能,然后将所设计的自抗扰控制器与实际系统采用的PI控制器的控制精度进行了对比分析。文章为进一步提高陀螺稳定平台的控制性能,提供了一种新的高精度的控制策略。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.