非球面光学系统的光路计算与分析

针对非球面光学系统,讨论高次非球面光路计算问题,使用"辅助二次曲面"方法,很好地解决了非球面的光路计算问题,可直接应用于非球面光学系统的设计优化程序。     

Vibration control efficiency of piezoelectric shunt damping system

The piezoelectric shunt damping technique based on the direct piezoelectric effect has been known as a simple, low-lost, lightweight, and easy to implement method for passive damping control of structural vibration. In this technique, a piezoelectric material is used to transform mechanical energy to electrical energy. When applying the piezoelectric shunt damping technique to passively control structural vibration, the piezoelectric materials must be bonded on or embedded in host structure where large strain is induced during vibration, thus to ensure vibrational mechanical energy to be transformed into electrical energy as much as possible. In this paper, the concept of vibration control efficiency of a piezoelectric shunt damping system is proposed and studied theoretically and experimentally. In the study, PZT patches are used as energy converter, and the vibration control efficiency is expressed by the vibration reduction rate per area of the PZT patches. Emphasis is laid on the effect of the generalized electromechanical coupling coefficient K ₃₁ on the vibration control efficiency. Four PZT patches with different sizes are bonded on the geometrical central area of four similar clamped aluminum plates, respectively, and vibration control experiments are conducted for these plates using the R-L shunt circuit. The results indicate that the bigger the coupling coefficient K ₃₁, the larger the rate of vibration reduction, and hence, the higher the vibration control efficiency. It also shows that the vibration responses of the first mode of the plates bonded with different PZT patches can be reduced by about 30.5%, 48.58%, 85.47%, and 89.91%, respectively. It comes to a conclusion that the vibration control efficiency of the piezoelectric shunt damping system decreases with the increase of the area of the PZT patch, whereas the vibration reduction of the plate increases with the area of the PZT patch. Therefore, it is necessary to make topology optimization for the PZT patch in the vibration control utilizing the piezoelectric shunt damping technique.     

Vibration control efficiency of piezoelectric shunt damping system

The piezoelectric shunt damping technique based on the direct piezoelectric effect has been known as a simple, low-lost, lightweight, and easy to implement method for passive damping control of structural vibration. In this technique, a piezoelectric material is used to transform mechanical energy to electrical energy. When applying the piezoelectric shunt damping technique to passively control structural vibration, the piezoelectric materials must be bonded on or embedded in host structure where large strain is induced during vibration, thus to ensure vibrational mechanical energy to be transformed into electrical energy as much as possible. In this paper, the concept of vibration control efficiency of a piezoelectric shunt damping system is proposed and studied theoretically and experimentally. In the study, PZT patches are used as energy converter, and the vibration control efficiency is expressed by the vibration reduction rate per area of the PZT patches. Emphasis is laid on the effect of the generalized electromechanical coupling coefficient K₃₁ on the vibration control efficiency. Four PZT patches with different sizes are bonded on the geometrical central area of four similar clamped aluminum plates, respectively, and vibration control experiments are conducted for these plates using the R-L shunt circuit. The results indicate that the bigger the coupling coefficient K₃₁, the larger the rate of vibration reduction, and hence, the higher the vibration control efficiency. It also shows that the vibration responses of the first mode of the plates bonded with different PZT patches can be reduced by about 30.5%，48.58%，85.47%, and 89.91%, respectively. It comes to a conclusion that the vibration control efficiency of the piezoelectric shunt damping system decreases with the increase of the area of the PZT patch, whereas the vibration reduction of the plate increases with the area of the PZT patch. Therefore, it is necessary to make topology optimization for the PZT patch in the vibration control utilizing the piezoelectric shunt damping technique.     

基于铌酸锂制作光弹调制器用压电驱动器

基于石英(SiO2)制作光弹调制器(PEM)的压电驱动器时,存在机电耦合系数小、需高压驱动且谐振频率随温度漂移严重等缺陷,故本文研究了PEM的优化设计方法。考虑铌酸锂(LiNbO3)特殊的晶体结构,从理论上推导了LiNbO3晶片作为压电驱动器的可行性,并确定其切型为zyw/35°切。基于有限元分析软件COMSOL4.3a仿真,确定了晶片体积和谐振频率,设计了LiNbO3压电驱动器。对设计出的压电驱动器进行了压电性能测试,并和SiO2压电驱动器进行了比较。将LiNbO3压电驱动器和硒化锌(ZnSe)光弹晶体组合成PEM,用671nm激光进行了光弹调制实验。实验结果表明:实现相同位移时,SiO2压电驱动器需要的驱动电压是LiNbO3压电驱动器的100多倍,且后者横向长度伸缩振动模式单一性和稳定性均优于前者。驱动电压为3.76V时,671nm的激光通过基于LiNbO3压电驱动器的PEM的调制光程差为3.7μm。得到的结果表明:基于LiNbO3压电驱动器的PEM易于驱动控制,调制性能优于基于SiO2驱动器的PEM。     

基于路径识别的巡线机器人控制系统设计

本文主要介绍了基于摄像头的黑线识别以及相应的控制策略.在获得路径图像的同时,实时图像处理系统识别黑线中心,从而判断出路径的信息,对智能车的舵机和速度施行控制,使之达到较为准确的转弯和快速行驶的性能.首先,在摄像头所获取的图像信息基础上,在图像预处理中使用了二值化和图像滤波算法,并且在黑线提取中提出了重心提取算法,以预判前方的路径信息;然后,根据所获得的路径信息控制舵机转向和行驶速度.实验表明,该方法简便可靠,能够满足机器人路径识别的需求.     

A piezoelectric resonator for optical power measurement with radiation beam quality retaining

A method for measuring the power of laser radiation in a wide range of wavelengths is introduced. The method is based on weak heating of an optically transparent piezoelectric resonator through which laser radiation is transmitted. After passing through such a resonator, the beam quality of laser radiation remains unchanged and the optical power can be utilized in laser technologies.     

双光路信号段交替合成压缩加密系统研究

介绍了一种光信号时域压缩的双光路信号段切换处理方法,在全光系统中实现了光信号分段切换,避免电子系统中存在的抗电磁干扰能力差等固有缺陷。红激光差拍干涉形成的移动干涉条纹等间隔匀速擦除由紫外光差拍干涉形成的移动光腔。通过调整系统参数,使两光波导之间写入光栅和擦除光条纹的移动速度分别相同,实现在同一时刻,两光波导对应位置的擦除红光明暗条纹分布相反,使得双路输入光信号被压缩切换到一路光信号输出,从而实现光信号的分段切换,可用于置乱加密等信号处理装置。     

Design of a piezoelectric transducer cylindrical phase modulator for simulating acoustic emission signals

To conveniently carry out the pipeline leak experiment in a laboratory, leak acoustic signals are simulated by using the converse piezoelectric effect of a piezoelectric transducer (PZT) cylindrical phase modulator. On the basis of the piezoelectric equations and electromechanical equivalence principle, the transfer function of a PZT cylindrical phase modulator is delivered. A PZT cylindrical phase modulator is designed, and the numerical simulation is conducted. Results prove that the PZT cylindrical phase modulator can effectively simulate leak acoustic emission signals when the frequency is lower than 25 KHz. __________ Translated from Journal of Beijing University of Technology, 2006, 32(8): 683–687 [译自: 北京工业大学学报]     

A path tracking control algorithm for underwater mining vehicles

In this paper, a path tracking control algorithm is formulated for the use of tracked underwater mining vehicles. The algorithm consists of two parts, the forward velocity control and the heading angle control. The control algorithm is designed based on kinematics, and it considers the track slips and the longitudinal and yaw dynamic models of the tracked vehicle including the soil-track interaction force model. The desired heading angle is obtained by the so-called “Line of Sight” method. The suggested algorithm is tested by numerical simulations using the TRACSIM software developed by MOERO/KORDI, Korea. After the control gains are tuned by a series of numerical simulations, the algorithm is verified on a scale vehicle on air on a soil bin test bed containing the cohesive soil of the Bentonite-water mixture. This paper was recommended for publication in revised form by Associate Editor Kyongsu Yi Sup Hong received the B.Sc. and the M.sc. degree in the department of naval architecture and ocean engineering from Seoul National University, Korea, and the Doctor of Engineering degree in mechanical engineering from the Technical university of Aachen, Germany. Currently, he is the principal researcher at MOERI (Maritime and Ocean Engineering Research Institute), Korea. His main research areas include dynamics of marine structure, and development of marine mineral resources. Especially, he is focusing on the development of deep seabed mining technologies since 1994. Mooncheol Won received the B.Sc. and the M.sc. degree in the department of naval architecture and ocean engineering from Seoul National University, Korea, and the Ph.D. degree in mechanical engineering from the University of California at Berkeley, USA. Currently, he is a professor in the department of mechatronics engineering of Chungnam national university, Korea. His research interests include control of maritime and mechatronics systems, and machine learning applications of robotic systems.     

空间光学遥感器扫描控制系统设计

研究了正弦波永磁同步电机驱动的空间光学遥感器扫描控制系统。采用复合控制与微分负反馈相结合的控制策略,实现了扫描镜的低速高精度往复运动。分析了扫描镜运动的数学模型,建立了d-q坐标系下的永磁同步电机数学模型;采用id=0矢量控制策略,在MATLAB/SIMULINK环境下搭建了基于空间矢量脉宽调制技术的控制系统仿真模型,设计了电流环、速度环和位置环调节器,给出了仿真结果。实验验证显示:采用复合控制后,仿真得到恒速运行的平均速度误差由1.27%优化到0.92%,扫描镜在恒速扫描过程中稳态平均角速度误差为2.06%,满足扫描镜系统速度精度优于5%的设计要求。理论分析、仿真和实验证明:该控制方法能够较好地改善控制系统的动态特性,具有调节时间短、超调小和动态响应准确等优点。     

光开关技术及其控制系统

光开关是全光网络中的关键器件.介绍光开关在光传输交换中的功能,分析光开关的性能要求与指标参数.基于不同工作原理,介绍了典型光开关及其技术特点与性能.最后分析光开关控制系统,将其分为控制单元、驱动单元、执行单元和反馈单元四部分.     

可控磁路式并联型永磁悬浮系统

提出一种主要由伺服电机、径向磁化盘状永磁铁、"F"形导磁体及悬浮物构成的可控磁路式并联型永磁悬浮系统。系统中,并联悬浮物是置于导磁体正下方两个不同重量的铁球,伺服电机驱动盘状永磁铁旋转,改变通过悬浮物的有效磁通量,进而控制悬浮力大小,实现两铁球的稳定悬浮。根据系统结构及可控磁路式并联型永磁悬浮原理将系统模型简化,并建立系统的数学模型,分析使系统稳定悬浮的可能性,计算使系统稳定悬浮的PD控制器反馈增益范围。实验结果表明:在控制器参数满足计算范围条件下,当给系统一较小阶跃外扰时,在实时控制系统作用下,系统在很短的响应时间内可达到新的稳定悬浮状态;相同的外扰可导致左右球异向的位移响应结果,左球移动方向与外扰相同,而右球相反。     

Tests of an adaptive optical system on a model atmospheric turbulent path

Physical modeling is a powerful tool for studying and testing various technical objects. In tests of an adaptive optical system (AOS), it is necessary to measure phase distortions of real objects (paths, devices, etc.) to identify real requirements and ranges of modeling. This paper presents estimates of modeling conditions and results of AOS tests under model conditions, namely, experimental results of adaptive correction of a laser radiation wavefront in a turbulent atmospheric path ∼100 m long. In the experiments, the standard deviation of the wavefront and the divergence of the radiation before and during the correction were recorded. In some cases, the correction efficiency in terms of standard deviation exceeded 10 times.     

Acousto-optic modulator system for femtosecond laser pulses

Femtosecond laser pulses have made a revolution in multiphoton excitation microscopy, micromachining, and optical storage for their unprecedented high peak power. However, modulation of their intensity with acousto-optic modulator (AOM) is frustrated by dispersion which results in a significant stretch in pulse width. Here we report a scheme composed of two acousto-optic deflectors (AODs) to modulate the intensity of the femtosecond laser pulses with simultaneous compensation for the temporal dispersion. With commercial AODs, we demonstrated such an AOM system for the femtosecond laser pulses with overall transmission efficiency of around 80%. The pulse width of the exit beam is 115-177 fs for an input pulse of 110 fs, across the wavelength range of 720-920 nm when the temporal dispersion compensation is optimally tuned at 800 nm. The fluorescence intensity in a two-photon microscopy experiment performed using this system increased 5.5-fold over that of the uncompensated AOM.     

光学电压传感器互易性光路研究

提高光学电压传感器光路中光波相位差传输稳定性的关键是对系统光路寄生干扰相位差的抑制。为此研究了一种基于晶体材料Pockels效应,并结合sagnac光路结构形成的光学电压传感器,在分析该光路结构互易性机理基础上,提出了将系统光路改为使用熊猫型保偏光纤和低双折射旋转光纤相结合的形式以消除光敏感电路段产生的模式相位差,从而提高了传感器光路互易性。建立了系统光路温度场与热应力数学模型,利用有限元仿真研究了外界环境温度对其相位差传播产生的影响特性,得到外界温度每增加1℃,光路双折射平均减小2.275 21×10~(-7)。基于此,对该互易性光路进行了实验研究,实验表明:温度对测量结果最大影响为1.733 9%/℃,当环境温度上升10℃时,相比光路全采用熊猫型保偏光纤,传感器测量准确度从6.008%提高至1.53%;当温度上升20℃时,准确度从52.016%提高至8.13%。可初步证明该互易性光路的可行性。     

压电陶瓷与电流变液结合的声学与振动控制系统

通过分别制备高性能压电陶瓷FD3-PZT,FD4-PZT和复合电流变液并测量它们的性能之后,研究和制作了由压电陶瓷与电流变液结合的一种新型声学与振动控制系统(在该系统中的压电陶瓷与电流变液之间连接有一高压延迟电路).当外界施加一个瞬时冲击力作用于该新型声学和振动控制系统中的压电陶瓷上时,压电陶瓷由于压电效应产生瞬时高压(d-c current)输入复合电流变液,电流变液在短时由于其具有的流变性(其电致流变性可逆)而迅速由液态变为固态,从而抵消了外来的瞬时冲击力.该新型声学与振动控制系统在振动控制和声学方面极有应用前景,例如抗(防)次声、声震波和爆炸冲击波的危害以及用于制造高效防弹衣、防护头盔(安全帽)等;在声学方面可制备新型电控激励器、制动器、强振隔离体、无后坐力装备及各种抗震、减振、防噪所需装置等.     

基于模式识别的压电精密驱动与控制系统

提出了基于图像识别技术的精密驱动与控制系统,以及将驱动系统分为步进电机丝杠的宏驱动系统和压电驱动器的精密驱动系统,并将两者有机地结合成完整宏/微的驱动系统。并且提出了基于计算机视觉技术与串口通信技术相结合的控制系统。这个精密驱动与控制系统的微操作平台连接上不同的机械执行机构就可以用于不同的精密加工和制造系统中。     

Multichannel control system for an acousto-optical modulator of laser radiation based on direct digital synthesis of frequencies

A module of control of an acousto-optical modulator of laser radiation in a multifrequency mode on the basis of a multichannel synthesizer with direct digital synthesis of frequencies is described. Specific features of system operation during multichannel laser recording with controlled amplitude, phase, and frequency of the channels with automatic calibration of intensity in each channel are considered. Application of the system in a photoplotter for producing photomasks of printed circuit boards makes it possible to increase the resolution of the device and to improve stability and reproducibility of recording.     

基于路径规划的粮食物流输送控制系统设计

为了解决传统地区粮食仓储物流存在的输送效率低,劳动强度大等问题,设计了基于路径规划的自动化粮食仓储物流智能输送控制系统.该系统由西门子PLC主控制器,扩展输入输出模块,人机界面模块,传感器模块,电机等执行模块构成.通过分析控制系统原理,确定PLC输入输出信号,设计电气接线图,软件程序及人机界面.运行结果表明:该系统实现...