三悬线式光学头力矩器低频特性分析

光学头力矩器是BD/DVD系统最重要的部件之一,其力学特性决定着光学读取头的性能。力矩器的阻尼特性是力矩器重要的特性之一,影响着力矩器的响应幅值和响应灵敏度。文中建立力矩器的力学模型,采用有限元软件ANSYS中的等效阻尼系统模拟力矩器的阻尼特性,仿真得到了力矩器的低频特性参数,与实验结果对比,验证了仿真模型的正确性。     

光学头三维悬线式力矩器的高次谐振

研究了分布在聚焦和循迹特性曲线上的高次谐振。对高次谐振的产生机理、物理模型、模态分布和测试方法等进行了研究。根据三维力矩器实际受力状况建立了低转角转动物理模型。利用有限元法分析计算了三维悬线式力矩器的模态分布和振型。介绍了高次谐振的测试方法,并对存在装配误差的力矩器进行实测。测试结果表明:不良力矩器往往在聚焦特性曲线上存在1 700 Hz左右的俯仰共振,在循迹特性曲线上存在4 800 Hz左右的偏转共振,其结果和有限元分析结果一致。结果还表明:高次谐振是光学头三维力矩器的固有属性,抑制高次谐振需要有效减小三维力矩器的装配误差。     

三悬线式光学头力矩器等效刚度模型

一阶共振频率是光学头力矩器的重要特性之一,研究的力矩器在聚焦方向、循迹方向和倾斜补偿方向上的固有频率分别为50.5 Hz,54.8 Hz和205.2 Hz。力矩器中支承部件悬线当作悬臂梁处理,利用材料力学和振动理论中梁挠度理论,将力矩器的受力转化为悬线受力,建立了力矩器的在聚焦运动、循迹运动和倾斜补偿运动三个方向的等效刚度模型,等效刚度模型计算结果与仿真结果、实验结果对比,误差均小于1%。     

用有限元和灵敏度分析法改善 光学头力矩器高频动态特性

在分析了力矩器高频共振机理的基础上,通过有限元仿真分析,研究了影响力矩器高频动态特性的因素。采用有限元仿真和灵敏度分析相结合的方法找出各影响因素的贡献率,优化了结构设计参数。结果表明:聚焦和循迹方向的二阶共振频率分别提高了6.6%和17.5%,明显提高了力矩器的高频动态性能。该方法可以广泛应用于其它优化设计领域。     

用于蓝光光学头的力矩器的动力学特性分析

作为光学读取头中的最终执行部件，力矩器在驱动电流的作用下带动物镜上下运动，高频动态跟踪光盘上信息坑位置的高频小幅移动。力矩器的动态性能直接决定着聚焦伺服和循迹伺服的精度，也就决定着光学头的读盘性能。本文结合蓝光光学头这一项目，针对用于蓝光光学头中的力矩器，用有限元方法进行了动力学仿真分析。首先建立了力矩器的有限元模型，设置材料参数并划分或建立单元；接着进行了力矩器可动部的模态分析，并对几种特定模态进行了阐述；然后进行了力矩器可动部的谐响应分析；最后给出了实验测试结果，验证了仿真模型的有效性。     

高隔离度光学环形器偏振灵敏度分析

本文在介绍一种光学环形器基本原理和结构的基础上,着重分析了影响该环形器偏振灵敏度的因素,给出了偏振灵敏度的数学表达式。实验研制的光学环形器的测试值与理论值吻合较好。     

电磁平衡头齿盘齿形参数对自锁力矩的影响研究

针对电磁主动平衡头自锁力矩问题,通过大量仿真分析的方法,得出了磁盘参数对自锁力矩的影响规律.首先,根据磁路自锁原理,针对特定结构,将自锁磁路简化为由磁盘、永磁体和支撑环3个零件构成的结构并建立了三维模型;其次,借助有限元分析的方法,通过改变单一变量,分别计算了齿盘上不同齿数、齿长、齿边距、齿张角对自锁力矩峰值的影响;最...     

用光学对点器快速安置经纬仪

本文介绍快速安置经纬仪的方法 ,按其步骤实践可在 2min内在测点上快速安置好经纬仪 ,且用图解方法指出其原理 ,从而在理论上给予证明 ,说明该方法的正确性。     

双进给珩磨头灵敏度元分析及结构优化

双进给珩磨头,可保证工件一次安装后完成粗、精两道珩磨工序提高加工精度。而采用非接触式气动测量,使珩磨头在加工中实现自动测量,避免了接触式测头对工件的划伤及测头的磨损,同时又减小了机床振动、热变形等对测量精度的影响。因此,双进给珩磨头的灵敏度对加工质量的影响非常大。通过ANSYS软件建模对不同结构参数的珩磨头进行实际加工应用实验,力学分析及灵敏度分析以便简化计算的结果,从而得出影响双进给珩磨头刚度的关键因素,得到结构参数对加工质量影响的规律。     

阵列式光学层析传感器的灵敏度分布计算与分析

对阵列式光学层析传感器灵敏度分布进行分析与计算不仅有利于了解激励光场与被测物质特性之间的相互作用关系 ,而且对于优化阵列式传感器的空间结构 ,提高成像质量以及进一步对光 CT层析图进行合理的解释均具有指导意义。光学层析传感器的灵敏度分布主要与光波长、被测物质的消光能力及传感器的空间结构形式有关。采用网格法对被测区域进行剖分 ,分析多方向角扇束光在监测区域中的二维空间分布格局以及对灵敏度系数进行归一化处理 ,提出了光层析传感器的灵敏度分布图的近似数值计算方法。并分析了不同传感器阵列结构对灵敏度水平、均匀性和空间分辨率的影响     

Rapid prototyping in the development of optical pickup unit

Rapid prototyping (RP) has already proven itself in the electronics industry as a method for shortening the product development time cycle. In the development of the optical pickup unit (OPU), extremely high precision is needed to make a functional model. Very often, in the design phase of the product development cycle, the prototype of the OPU is machined from a single piece of aluminium block to make the working sample. In this project, a comparison of the machined aluminium sample, RP samples from various RP processes and that moulded out from the injection moulding machine is made on surface finishing as well as dimensional accuracy. Finally, a comparison of tooling cost, piece part cost and lead time of obtaining the parts is also discussed on the different prototyping and manufacturing processes.     

Influence of contact wire pre-sag on the dynamics of pantograph-railway catenary

Stiffness variations and wave propagation in railway catenaries are the main sources of contact loss between the pantograph and the railway catenary. The pre-sag of a contact wire is sometimes introduced to compensate for the stiffness variation. To include the pre-sag’s influence on the dynamic interaction of the pantograph-catenary, we present a modified single-degree-of-freedom (SDOF) dynamic system with a time-varying stiffness that is based on a simplified model from a previous study. The pantograph-catenary parameters that are related to the optimal pre-sag to minimise variations in the contact force are obtained by solving the equations of the SDOF dynamic system. The amount of optimal pre-sag is determined from parameters such as speed, span length, uplift, and the stiffness variation coefficient. Because wave propagation is not allowed in the SDOF model, we investigate the influence of pre-sag on the dynamic interaction between the pantograph and the catenary by using both SDOF and finite element method (FEM) models. These models show that, by using the optimal pre-sag, we can significantly reduce the variation in the contact force in the medium-speed range, which is near the 1/2 sub-resonance speed. The influence of pre-sag is confirmed by a field test that was performed on a Korean conventional catenary. However, the FEM model shows that in the high-speed range near 300 km h⁻¹, the introduction of the pre-sag can reduce the variation in the contact force slightly only if uplift force subject to the pantograph is large enough to cause slackening in the droppers next to the supports. Otherwise, it does not reduce the variation in the contact force. The FEM also shows that the optimal pre-sag (less than 1/2000 of span length) in the high-speed range is much smaller than that (about 1/1000 of span length) in the medium-speed range.     

Design and analysis of a mini linear optical pickup actuator

This paper describes a mini linear optical pickup actuator. To reduce the size, inner yokes are designed to guide the mover and outer yokes of permanent magnets are removed. Magnetic circuit method is used to determine the thrust force. Virtual path method is proposed to analyze the open magnetic circuit analysis. The magnetic circuit of the proposed actuator can be a closed circuit due to the virtual path model of the outer magnetic flux. The validity of virtual path method is evaluated by comparing to the FEM analysis. Structural vibration is investigated using FEM and the design of the mover is modified to improve the vibration characteristic. Dynamic characteristic experiments shows that the performance of the proposed actuator is enough to be used as a coarse and fine seeking actuator simultaneously and the thrust force margin for loading a focusing actuator is guaranteed.     

A numerical study on dynamic characteristics of a catenary

Dynamic characteristics of a catenary that supplies electrical power to high-speed railway is investigated. The catenary is a slender structure composed of repeating spans. Each span is in turn composed of the contact and messenger wires connected by the hangers in regular intervals. A finite element based dynamic model is developed, and numerical simulations are performed to determine the dynamic characteristics of the catenary. The influence of the structural parameters on the response characteristics is investigated. The structural parameters considered include tension on the contact and messenger wires, stiffness of the hangers, and the hanger and span spacing. The hanger characteristics are found to be the dominant factors that influence the overall dynamic characteristics of the catenary.     

基于DSP LF2407A的啮合式微型电机控制驱动器

啮合式微型电机是一种新型电机,作为一种与磁阻电机类似的电机,其控制驱动需要专门的控制驱动器实现。文中介绍了一种基于DSP2407的适合于啮合式微型电机的控制驱动器,利用该控制驱动器实现了啮合式微型电机的斩波恒流驱动、细分驱动控制。     

钛对LF9镍基合金力学性能的影响

采用SEM、TEM、XRD、化学相分析及拉伸试验等方法,对不同钛含量的四种LF9合金的组织和力学性能进行了研究.结果表明:随着合金中钛含量的提高,合金的室温和高温强度随之提高,而塑性和韧性随之下降.这主要是由于随着钛含量的提高,γ'、γ″、η相的析出数量增多、尺寸增大及形态改变所造成的,其中η相的影响更显著.     

Facilitating the pickup of individual DNA molecules by AFM nanomanipulation with tips mechanically worn on bare mica

The tip is one of the critical factors to improve the efficiency in picking up individual DNA molecules from solid substrates based on atomic force microscope (AFM) nanomanipulation. We found that wearing AFM tips on certain solid substrates in advance to nanomanipulation operation would largely improve the pickup efficiency, which was ascribed to the increasing affinity of the tip to the DNA molecules along with the increase of the tip radius after wearing. It was demonstrated that bare mica was superior to APTES-modified mica to keep the tip clean while wearing, which was crucial for DNA pickup during AFM nanomanipulation.     

悬架扭杆和稳定杆刚度对车辆转向灵敏度的影响分析

为研究悬架和横向稳定杆的刚度对车辆操纵性能的影响,进而为悬架设计和调整提供参考,以某轻型客车为原型,在ADAMS/Car中构建了无横向稳定杆和前悬架装配横向稳定杆的两辆虚拟样车及其变型车,通过转向盘转角阶跃输入仿真试验,得到了前悬架扭杆和横向稳定杆角刚度对车辆转向灵敏度的影响曲线。研究结果表明,对于无、有稳定杆两种车型,扭杆角刚度自0.5倍增大至2.0倍基准刚度,转向灵敏度分别产生相对于经验值域约20%和1%的下降量;横向稳定杆角刚度自基准角刚度减小至0或增大至2.0倍基准刚度,转向灵敏度分别产生相对于经验值域约10%的增长量或1%的下降量。