激光陀螺锁区测试系统

介绍了激光陀螺仪的原理和应用,以及激光陀螺仪自锁效应产生的机理.重点研究了激光陀螺仪锁区测试系统的设计和使用方法.本文所研究的激光陀螺锁区自动测试系统是由计算机控制的智能化测试设备,通过与被测产品激光陀螺在电气上直接连接,能够自动完成对激光陀螺锁区的测试工作,并记录测试结果.该测试系统具有良好的可维护性和可开发的适应性,使用安全、可靠、高效.     

激光陀螺测角仪的角度计量误差分析

随着激光陀螺制造工艺的逐渐成熟以及闭锁等难题的突破,激光陀螺测角仪已成为高精度、高灵敏度、多参量测角仪器。本文针对其计量性能开展了测试,并详细分析了激光陀螺测角仪系统误差的主要来源,包括激光陀螺测角仪的安装误差、转台不水平误差、转速不稳定误差三项主要误差源,并仿真分析了各因素引入误差的大小,同时采用经典Allan方差法分析了激光陀螺测角仪的随机误差,结果表明：激光陀螺测角仪的综合测角不确定度为0.4″,角度测量误差优于±0.5″。     

基于小波降噪算法的动态测试系统

针对目前陀螺导航装备缺乏动态性能测试方法的状况,本文提出并实现了车载动态性能测试系统.并根据航向数据非连续变化的特点,提出了基于周期平移的小波阈值降噪算法.该算法通过对信号的分段周期平移、阈值降噪、逆平移的方法实现降噪,有效地克服了常规小波阈值降噪算法带来的Pseudo-Gibbs现象.仿真及实测数据表明采用该算法能够在有效剔除异常点、消除噪声的同时,消除降噪信号中的Pseudo-Gibbs现象.跑车实验表明车载动态性能测试系统为陀螺导航设备提供了有效的解决方案和统一的测试平台.     

激光陀螺中残余气体对其性能的影响分析及激光陀螺吸气剂的选择

利用四极质谱仪,通过实验分析了激光陀螺存储过程中释放的微量残余气体成分及其对激光陀螺光强的影响,进而分析了其对激光陀螺工作性能的影响;建立了激光陀螺吸气剂性能测试系统,通过实验测试了多种型号吸气剂室温条件下吸气性能,结合实验结果从理论上分析了这些不同型号吸气剂的吸气原理。实验结果表明,综合考虑吸气剂的吸气能力和抗恶劣环境能力,TPYZ型吸气剂是性能较好的适用于激光陀螺的吸气剂,它的使用将较好地解决激光陀螺存储过程中释放微量残余气体带来不利影响的问题。     

机抖激光陀螺稳频控制技术

激光陀螺的工作中心频率作为激光陀螺的工作计量基准,其频率的稳定性对激光陀螺的测量精度有着直接的影响．稳定激光陀螺工作中心频率最为有效的方法就是采用主动腔长补偿控制．在对腔长控制原理和方法介绍的基础上,提出了将激光陀螺输出光强信号进行交直流分量分离独立控制的方法,并给出了系统的硬件设计框图,最后介绍了软件设计流程．测试结果表明漂移均方差在0．4°·h-1以内,满足系统的使用要求．     

基于FPGA和DSP的激光陀螺信号处理电路设计

研究机械抖动激光陀螺的信号读出系统,设计激光陀螺的信号处理电路。光电转换后的微弱电流信号经过前置放大电路转化为电压方波信号,在FPGA中进行鉴相解调以及可逆计数,最后由DSP实现机抖偏频解噪和低通数字滤波。与激光陀螺联合测试并将结果输出至上位机,结果表明设计的电路实现了对激光陀螺输出信号的有效采集,满足激光陀螺功能测试的需要。     

基于滑动滤波技术的激光陀螺评价方法

激光陀螺是一种以量化脉冲的形式输出角增量的数字传感器,量化误差如同白噪声一样影响着激光陀螺的测试精度。为了准确评价激光陀螺的性能,减少量化误差对激光陀螺测试数据的影响,本文应用滑动滤波技术对激光陀螺采样数据进行滤波处理,理论分析及实验结果表明,该方法有效地降低了量化噪声从而实现了对激光陀螺的准确评价。     

激光陀螺及减小闭锁效应的方法

主要介绍了激光陀螺的工作原理——Sapnac效应;并对减小闭锁效应的光学抖动及机械抖动方法进行了分析比较。     

基于Lighttools的激光陀螺光学仿真

LightTools是一个全新的具有光学精度的交互式三维实体建模软件体系,在系统初步设计、复杂系统设计规划、照明系统设计分析等方面发挥重要作用。介绍一种基于Lighttools的激光陀螺光学仿真,依靠Lighttools完成对激光陀螺光学模型的建立,并对模型可靠性进行测试,从而在实际的陀螺生产中提供设计指导。     

基于视觉的环形激光陀螺自动调腔系统

针对激光陀螺调腔,设计了一种基于视觉的自动调腔系统.采用基于统计的图像分析方法,对激光陀螺光学谐振腔中的光阑和光束进行定位.根据几何光学,分析了谐振腔中反射镜位置失调与光束偏移之间的关系,并设计了基于图像的闭环位置控制律,对反射镜的位置进行调整.实验表明,该系统能够完成对光阑和光束的自动识别,能够较好地实现激光陀螺的调腔.     

跑道异物检测光学传感器舱环控系统实验研究

通过对机场跑道异物检测光学传感器舱内温度以及环控系统运行参数的实验测试,分析镜头类型、环控系统控制方式及控制参数对舱内温度的影响.实验结果表明:镜头类型对舱内空气平均温度稳态变化值影响小于3％;环控系统采用串级调节,供液温度设置为28℃,压缩机差动范围设置为1℃,主调节器死区温度取0.2℃、采样时间取10min、比例系...     

等径角挤压过程中材料的流变行为研究

分析了等径角挤压过程中材料流变的原因和特征,认为每道次挤压材料内部发生的剪切变形量与时间的函数曲线呈近似正态分布,适当升高温度和增加背压能有效减小难变形区,降低通道与试样接触面之间的摩擦能减小材料内部的滞变区.通过实验证明,随着挤压道次的增加,材料内部的滞变区将减小,均匀化程度会逐步提高.     

Cr3+掺杂对快速生长KDP晶体的生长习性和光学性能的影响

采用快速法生长了掺杂不同Cr3+浓度的KDP晶体,测试了KDP晶体(100)面在不同Cr3+掺杂浓度下的生长速度及死区,表征了Cr3+掺杂的KDP晶体的Cr3+元素分布、透过光谱、散射颗粒分布和光损伤阈值.实验表明Cr3+易吸附在晶体(100)面,从而增大了(100)生长死区,并降低了(100)面生长速度.Cr3+使快...     

基于卡尔曼滤波滑模控制的伺服系统设计仿真

应用变结构控制策略时,由于系统存在时间滞后、空间滞后、死区等不利条件,会导致系统运行到相平面中滑动面时出现不期望的抖振现象.本文分析了抖振对系统性能的影响及产生原因,针对伺服控制系统存在随机干扰和随机噪声的特性,提出一种基于卡尔曼滤波的指数趋近律滑模变结构控制算法,很好地抑制了抖振.仿真算例表明,与普通滑模控制算法相比,基于该算法的控制器无论在抖振抑制上还是在伺服系统动态品质改善上都具有良好效果.     

Concept of stress dead zone in cracked plates: Theoretical,experimental, and computational studies

This paper presents a study on stress dead zone implications and its characterization with uniaxial tensile testing on MT polycarbonate plate specimens. To obtain the experimental solution, digital image correlation (DIC) is used. Numerically, based on LEFM, the problem is solved using advanced discretization techniques, finite element, and meshless methods. Considering stress dead zone notion, it aims to determine alternative analytical solution of the SIF. Thus, the compliance method is adopted, which is associated with the specimen's dead zone region that does not involve the cracking resistance. Hence, LEFM formulations complying with strain energy release rate criterion are assumed. A proper comparison is made amongst results obtained from all theoretical, experimental, and numerical analyses. Furthermore, this work focuses on the variational fields' evaluation and, in particular, verification on the theoretical assumption of dead zone characteristics. The obtained results support adopted methodologies and are encouragingly robust and cost‐effective.     

数字化光电跟踪伺服系统定位极限环的抑制

数字光电跟踪系统定位时将产生自振荡,在相平面下可描述为极限环。自振荡对定位精度影响较大,因此必须对其进行抑制。针对实际的数字光电跟踪伺服系统,提出一种描述方法,即用等效间隙非线性来描述其定位时非线性特性,且该间隙主要由光电传感器的滞后效应和伺服系统的摩擦死区引起。理论分析表明,双极PWM功率放大器的零点振颤特性可以抑制伺服系统的定位极限环。实验也证明,通过软件补偿以及PWM驱动模式设计来改善光电跟踪系统定位精度是可行的,定位精度由1.77提高到了22.23,大大抑制了定位非线性特性。     

Thermal-light-based ranging using second-order coherence

A novel thermal-light-based ranging scheme utilizing second-order coherence in the time domain is proposed and studied. Such a scheme allows ultrahigh accuracy to be achieved for absolute range measurement. Besides, the scheme has the advantages of high immunity to noise and no measuring dead zone. A proof-of-principle experiment has been done, and the result shows a ±10 cm accuracy at a distance of 1 km, which is currently limited by our detectors. The accuracy can be greatly improved to the nanometer scale by using state-of-the-art detectors with an appropriate data processing algorithm.     

Optimal tool angles for equal channel angular extrusion of strain hardening materials by finite element analysis

Equal channel angular extrusion (ECAE) is a novel deformation process capable of imparting a large amount of plastic strain to bulk material through the application of uniform simple shear. ECAE die geometry, material properties and process conditions influence the shear deformation behavior during extrusion that in turn governs the microstructure and mechanical properties of the extruded materials. Finite element analysis, the most appropriate technique was used to analyze the deformation behavior of extruded materials without neglecting important and realistic factors like strain hardening behavior of the material, frictional conditions and speed of the process. In this study the deformation behavior of material, dead zone/corner gap formation and strain homogeneity achieved in the samples during ECAE were studied by using commercial finite element code Abaqus/Explicit. The influence of tool angles, strain hardening behavior of material and friction between the billet and die was considered for simulations. Results showed that the optimal strain homogeneity in the sample with lower dead zone formation, without involving any detrimental effects, can be achieved with channel angle of 90° and outer corner angle of 10°.     

Circadian clocks optimally adapt to sunlight for reliable synchronization

Circadian oscillation provides selection advantages through synchronization to the daylight cycle. However, a reliable clock must be designed through two conflicting properties: entrainability to synchronize internal time with periodic stimuli such as sunlight, and regularity to oscillate with a precise period. These two aspects do not easily coexist, because better entrainability favours higher sensitivity which may sacrifice regularity. To investigate conditions for satisfying the two properties, we analytically calculated the optimal phase–response curve with a variational method. Our results indicate an existence of a dead zone, i.e. a time period during which input stimuli neither advance nor delay the clock. A dead zone appears only when input stimuli obey the time course of actual solar radiation, but a simple sine curve cannot yield a dead zone. Our calculation demonstrates that every circadian clock with a dead zone is optimally adapted to the daylight cycle.     

大型调节阀死区的颤振补偿研究

针对大型电液调节阀的死区是导致其调节滞后的主要因素,分析了调节阀死区的产生原因,研究了在调节阀的执行机构叠加高频颤振进行死区补偿的机理。利用AMESim仿真软件,建立了电液调节阀的死区补偿模型,并对该模型进行了实验验证。在此基础上,讨论了颤振信号的幅值、频率和均值对死区补偿效果的影响。结果表明,通过叠加适当的高频颤振信号,使电液调节阀的执行机构始终处于微小的颤振状态,可以有效克服死区的影响,改善调节阀的动态响应特性,实现对调节阀死区的有效补偿。