基于GDOP的分布式雷达网航迹关联阈值选择新方法

分布式雷达组网的航迹关联不仅与网内各雷达的性能有关,而且与目标的相对位置有关。本文提出一种新的雷达组网航迹关联方法,该方法在综合网内各雷达性能的基础上,将组网雷达定位精度几何稀释模型引入航迹关联算法当中。根据各雷达对观测同一目标定位精度的差异为参考,给出一种新的航迹关联门限阈值选择算法。本文介绍了航迹关联阈值的计算过程,并利用该方法对真实航迹数据进行了仿真。     

寒冷地区新风机组热水盘管冻裂根源与防治方法

通过对中国计量科学研究院昌平院区工艺性空调系统新风机组热水盘管冻裂根源的分析,提出几种不同的防治方法,结合现场实际条件选出了一种最适合本系统的解决方案,以期通过本项目的成功实施能对寒冷地区类似空调系统的设计、施工和运行起到一定参考和指导作用。     

曲面重构模型精度分析研究

运用Geomagic Qulify软件,以测量点到曲面模型的距离为主要评价指标,对用传统曲面造型方式和快速曲面造型方式重构的鞋楦曲面分别进行质量评价,通过模型的3D比较、2D比较及特殊点的比较,得到模型的3D偏差图、误差分布百分比图表、截面标准偏差图和截面百分比偏差图,通过分析比较图表,可知两种曲面重构方式所得曲面均符合要求,可根据曲面重构质量的不同要求选择恰当的曲面重构方式,为其他模型的曲面测评和曲面重构方式的选择提供了参考依据。     

视觉检测与激光精密测量在轴承加工检测中的应用

机器视觉测量技术是利用机器模拟人类视觉对待测工件的各种参数进行测量的一种新兴技术,测量速度快。利用面阵CCD传感器拍摄图像并结合相应的平面标定算法,即可测得工件的平面尺寸。此方法测量速度快,但精度相对较低。高精度激光位移传感器的测量精度较高,但测量速度相对较慢。结合以上两种视觉传感器的优点,提出一种同时具有高速、高精度特点的精密测量方法,并将其应用在精密轴承的制造、加工、检测中。     

平面三滚柱定心夹具主要结构参数及公差分析

针对使用带平面三滚柱自定心夹具的工件需自锁并能方便松开的要求,分析了夹具各结构参数的公差对工件内孔尺寸精度要求的影响程度,提出了滚柱直径和楔紧平面到心轴中心距的公差计算方法。得出如下结论：工件内孔尺寸必须满足一定的精度要求;内孔所需的精度等级不仅与滚柱和楔紧平面到心轴中心距离的制造精度有关,还与工件内径的大小有关,且内径尺寸越大,所需的精度等级越低,为带平面三滚柱自定心夹具设计提供参考。     

插入式超声波温度计设计

基于超声波在棒状固体介质中传播速度与温度的关系,运用高速高分辨率的硬件电路和软件细分插补算法,精确地测量超声波的回波时间,从而精确地测量超声波的传播时间并计算出对应的温度值.根据在固体介质中传播时间和温度的关系建立数学模型,通过已测得的传播时间求出对应的温度值.设计的温度计结构简单,能够实时地测量液体温度的变化,并且能在各种高温环境中广泛应用.     

A Large Range Flexure-Based Servo System Supporting Precision Additive Manufacturing

This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography (MSL) process. As a key enabler of high accuracy in this process, a compact desktop-size beam flexure-based nanopositioner was designed with millimeter range and nanometric motion quality. This beam flexure-based motion system is highly suitable for harsh operation conditions, as no assembly or maintenance is required during the operation. From a mechanism design viewpoint, a mirror-symmetric arrangement and appropriate redundant constraints are crucial to reduce undesired parasitic motion. Detailed finite element analysis (FEA) was conducted and showed satisfactory mechanical features. With the identified dynamic models of the nanopositioner, real-time control strategies were designed and implemented into the monolithically fabricated prototype system, demonstrating the enhanced tracking capability of the MSL process. The servo system has both a millimeter operating range and a root mean square (RMS) tracking error of about 80 nm for a circular trajectory.     

精密弹簧固定件复合模设计

在对精密弹簧固定件作了充分工艺分析的基础上,确定了冲压加工工艺方案,通过排样设计,设计了落料、拉深、弯曲、冲孔复合模。并详细介绍了模具的结构特点和功能。     

Sphere mass center determination by velocity modulation

This paper presents a new technique, called velocity modulation, for measuring the mass center location of a sphere, improving upon the accuracy of previous methods by at least a factor of 4. The sphere is rolled down a set of parallel rails. The offset of the sphere’s mass center with respect to its geometric center modulates the sphere’s velocity at the rolling frequency, which is detected by a series of differential optical shadow sensors. The measured times that the sphere crosses the sensors is compared with a simplified mechanics model in order to recover the sphere’s mass center location. The precision of the technique is demonstrated by the repeatability of independent measurements in one plane of a 50.8 mm (2 in.) stainless steel gage sphere. The best standard deviation achieved is 145 nm (95% confidence interval = 227 nm).