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1.
Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode, this paper proposes a current measurement method based on triangular constant transformation to reconstruct magnetic rotation angle, so as to avoid the large current measurement error caused by the approximate measurement of the magnetic rotation angle. By extracting the direct current (DC) component and the alternating current (AC) component of the light intensity signal detected by the photoelectric detector (PD), the sine signal containing the magnetic rotation angle is directly obtained by dividing the two components, and then the triangular identity transformation method is used to linearly demodulate the magnetic rotation angle and reconstruct the current waveform. The experimental results show that the relative error of current measurement does not exceed 1.40% in the current range of 0.05—0.50 A, which is less than the approximate linear measurement (ALM) method, and the magnetic rotation angle and the current have a good linear relationship.  相似文献   

2.
In recent years, context aware technology has been widely used in many fields, such as internet of vehicles (IoV). Consistent context information plays a vital role in adapting a system to rapidly changing situations. However, sensor's precision variance, equipment heterogeneity, network delay and the difference of statistical algorithms can lead to inconsistency context and inappropriate services. In this paper, we present an effective algorithm of context inconsistent elimination which is based on feedback and adjusted basic reliability distribution. Through feedback, each sensor's perception precision can be obtained, and with the adjusted basic reliability distribution scheme, we can make full use of all context information by adjusting the influence of every context on whole judgment based on sensor's perception precision and threshold of sensor's perception precision, and then eliminate context inconsistency. In order to evaluate the performance of the proposed context inconsistency elimination algorithm, context aware rate is defined. The simulation results show that the proposed context inconsistency elimination algorithm can obtain the best context aware rate in most cases for the varied error rates of sensors.  相似文献   

3.
A multisensor distributed extended Kalman filtering algorithm is presented for nonlinear system, in which the dynamic equation of the system and the equations of sensor's measurements are linearized in the global estimate and global prediction respectively and the suboptimal global estimate based on all available information can be reconstructed from the estimates computed by local sensors based solely on their own local information and transmitted to the data fusion center. An analysis of the properties of the algorithm presented here shows that the global estimate has higher precision than the local one and smaller linearization error than the existing method. Finally, an application of the algorithm to radar/IR tracking of a maneuvering target is illustrated. Simulation results show the effectiveness of the algorithm.  相似文献   

4.
The multisensor detection area partitioning is considered. An approach is presented to the fusion in each detection area where the sensor uses different thresholds and then at system level. The expressions of the detection probability and false alarm probability are given. An application of the method is illustrated to distributed CFAR detection systems. The result shows that the system detection probability may be improved by setting different thresholds for a detector.  相似文献   

5.
Aiming at the problem of resource allocation in multiuser multi-input multi-output (MIMO) systems, a new power allocation algorithm based on dual waterfilling is proposed. Block diagonalization is adopted to cancel the inter-user interference, and then the complete diagonalization method is employed to derive the spatial sub-channels for each user. The overall power of the system is divided among users based on each user's large scale fading; then the power of each user is further allocated to its spatial sub-channels based on the small scale fading. Simulation results show that compared with the existing resource allocation strategies, the proposed algorithm can provide more ergodic capacity for multi-user MIMO systems. When the total transmit power is 100w, it has 15% capacity advantage over the traditional waterfilling method.  相似文献   

6.
刘洋  章国安 《光电子快报》2014,10(5):352-355
In order to mitigate atmospheric turbulence, the free space optical (FSO) system model with spatial diversity is ana- lyzed based on intensity detection pulse position modulation (PPM) in the weak turbulence atmosphere. The slot error rate (SER) calculating formula of the system without diversity is derived under pulse position modulation firstly. Then as a benchmark, independent of identical distribution, the average slot error rates of the three linear combining tech- nologies, which are the maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SelC), are compared. Simulation results show that the performance of system is the best improved by MRC, followed by EGC, and is poor by SelC, but SelC is simpler and more convenient. Spatial diversity is efficient to improve the performance and has strong ability on resistance to atmospheric channel decline. The above scheme is more suitable for optical wire- less communication systems.  相似文献   

7.
In a radio frequency identification (RFID) system, the backscattered signal is small and prone to interference. The performance of RFID tag identification in interference scenarios is degraded compared to that in error-free scenarios. In this paper, a novel Mahalanobis distance estimate (MDE) method is proposed to jointly estimate the number of tags and packet error rate (PER). The MDE method is error resilient owing to its ability to achieve a stable estimation when interference is impairing the observed information. The proposed method achieves significantly enhanced accuracy over existing methods by taking all the information and correlations among the observed results into account. The MDE method improves the estimate performance based on efficient decorrelation and classification of the observed information. Moreover, the performance of the PER estimate is analyzed both in theory and through simulations. It can be concluded from the analysis that the estimated PER is unbiased and variance-bounded. Simulations show that the proposed estimate outperforms the previous proposals in terms of accuracy and stability, which makes it suitable for application in interference scenarios.  相似文献   

8.
This paper presents a readout system for the passive pressure sensors which consist of a pressure- sensitive capacitor and an inductance coil to form an LC circuit. The LC circuit transforms the pressure variation into the LC resonant frequency shift. The proposed system is composed of a reader antenna inductively coupled to the sensor inductor, a measurement circuit, and a PC post-processing unit. The measurement circuit generates a DC output voltage related to the sensor's resonant frequency and converts the output voltage into digital form. The PC post-processing unit processes the digital data and calculates the sensor's resonant frequency. To test the performance of the readout system, a sensor is designed and fabricated based on low temperature co-fired ceramic (LTCC), and a series of testing experiments is carried out. The experimental results show good agreement with the impedance analyzer's results, their error is less than 2.5%, and the measured values are almost insensitive to the variation of readout distance. It proves that the proposed system is effective practically.  相似文献   

9.
Avalanche photodiodes(APDs) are promising light sensors with high quantum efficiency and low noise. It has been extensively used in radiation detection, laser radar and other weak signal detection fields. Unlike other photodiodes, APD is a very sensitive light detector with very high internal gain. The basic theory shows that the gain of APD is related to the temperature. The internal gain fluctuates with the variation of temperature. Investigated was the influence of the variation of the gain induced by the fluctuation of temperature on the output from APD for a very weak laser pulse input in laser radar. An active reverse-biased voltage compensation method is used to stabilize the gain of APD. An APD model is setup to simulate the detection of light pulse signal. The avalanche process, various noises and temperature's effect are all included in the model. Our results show that for the detection of weak light signal such as in laser radar, even a very small fluctuation of temperature could cause a great effect on APD's gain. The results show that the signal-tonoise ratio of the APD's output could be improved effectively with the active gain-control system.  相似文献   

10.
Attacks such as APT usually hide communication data in massive legitimate network traffic, and mining structurally complex and latent relationships among flow-based network traffic to detect attacks has become the focus of many initiatives. Effectively analyzing massive network security data with high dimensions for suspicious flow diagnosis is a huge challenge. In addition, the uneven distribution of network traffic does not fully reflect the differences of class sample features, resulting in the low accuracy of attack detection. To solve these problems, a novel approach called the fuzzy entropy weighted natural nearest neighbor(FEW-NNN) method is proposed to enhance the accuracy and efficiency of flowbased network traffic attack detection. First, the FEW-NNN method uses the Fisher score and deep graph feature learning algorithm to remove unimportant features and reduce the data dimension. Then, according to the proposed natural nearest neighbor searching algorithm(NNN_Searching), the density of data points, each class center and the smallest enclosing sphere radius are determined correspondingly. Finally, a fuzzy entropy weighted KNN classification method based on affinity is proposed, which mainly includes the following three steps: 1、 the feature weights of samples are calculated based on fuzzy entropy values, 2、 the fuzzy memberships of samples are determined based on affinity among samples, and 3、 K-neighbors are selected according to the class-conditional weighted Euclidean distance, the fuzzy membership value of the testing sample is calculated based on the membership of k-neighbors, and then all testing samples are classified according to the fuzzy membership value of the samples belonging to each class;that is, the attack type is determined. The method has been applied to the problem of attack detection and validated based on the famous KDD99 and CICIDS-2017 datasets. From the experimental results shown in this paper, it is observed that the FEW-NNN method improves the accuracy and efficiency of flow-based network traffic attack detection.  相似文献   

11.
本文从紫外光通信技术的发展趋势及研究背景出发 ,针对特定环境下实现目标定位的 应用需求,结合偏振光的振动特性,提出了基于偏振紫外光单次散射实现非视距目标定 位的方法。首先,基于紫外光大气散射传输特性,建立了偏振紫外光非视距单次散射模型, 利用矩阵光学的方法推导了紫外光偏振散射传输特性;建立了接收光强与方位角及收发距离 之间的关系。其次,利用Matlab软件仿真并分析了收发仰角及视场角对接收光强及方位角测 量范围的影响,选取了合适的收发仰角及视场角。根据接收信号光强随方位角的变化获得目 标方位角,并通过解算得出收发距离,理论上验证了系统可行性,并对各误差影响进行了仿 真分析,在距离500 m,收发仰角偏离(预设值25°)3°时,距离测量误差为25.3 m。噪声对光 强的影响导致方位角判定误差对测距误差的影响较小,但方位角判定误差为3°时,会引起 距 离500 m时真实位置横向偏离误差26.2 m。本 文研究结果为拓展紫外光通信系统的功能及实 际应用提供了理论基础,有一定的指导意义。  相似文献   

12.
顾帅  王宇野 《电子科技》2014,27(9):178-180
设计了一种基于光电传感技术的物体检测系统,采用红外发光二极管和红外光电三极管的方式,进行传感电路设计。使用单片机NUC130LE3CN进行发光强度的控制与接收端电平的检测,发光强度由单片机IO口输出PWM波形进行控制。利用发光强度可调节这一特性,该方案可在不同环境光强下达到较高的检测灵敏度,同时还可提供报错功能。  相似文献   

13.
为了提高测距的红外测距的精度,提出了以MSP430F149单片机为控制核心,红外线发射接收模块为传感器,通过测量红外发射管发出的红外线反射的光线强度来测量距离。此系统将测量的光线强度转换为电压信号,并测得电压信号和距离的对应关系,最后通过最小二乘法进行分段拟合,得到电压信号和距离的关系式以实现测距。该红外测距系统误差达到1 mm,可以广泛近距离测距和汽车防撞系统中。  相似文献   

14.
使用背照减薄型CCD器件的色散型成像光谱仪在近红外波段会出现呈条带状干涉条纹现象,该干涉条纹对入射光波长分布敏感,空间频率稳定,特别适用于微小光谱偏差的测量与校准.针对一台光栅色散型推扫式成像光谱仪样机,先估计出条纹分布的规律,再以此为基础,采用频域滤波、最小二乘拟合等方法提取干涉条纹中包含的相位信息,以此作为光谱定标的辅助参数.实验表明,当入射光强变化达到130%以上时,拟合谱线位置的不确定度最大为0.007 3 nm,模拟光谱位置改变后,以汞灯谱线作为基准光谱位置曲线,测得拟合算法的最大误差为0.135 8 nm,该结果证明,干涉条纹拟合定标方法可有效减少定标系统对光源稳定性的依赖,提高对光谱维微小偏移量的检测精度.  相似文献   

15.
提出一种新型的光纤智能结构监控系统,主要由光源组、光学系统、光电传感器、监控主机组成.分析了系统的工作原理,研究了基于此种新型光纤智能结构承载与损伤位置判别的方法,并进行了相应实验,得出相应的实验数据,并作出光纤网络输出光强与加载量的变化曲线图.经实验分析与讨论,实验数据与理论分析能较好地符合,结果表明这种新型光纤智能结构监控系统对结构的承载及损伤位置的判别方法具有快速、准确和可靠的优点,为特殊光纤智能结构的进一步应用提供了新途径.  相似文献   

16.
We propose a weighted average indoor positioning algorithm, which is an improved version of the M.S. Rahman’s algorithm, for the calculation of unknown positions in a visible light communication system consisting of light-emitting diodes (LEDs) and image sensors. The algorithm considers the LED illumination intensity as a key factor, and the generalized Lambert illumination model is adopted to estimate the LED illumination intensity of each pixel in the images obtained at the sensors. The LED illumination intensity is normalized as a weighting factor, following the determination of the center position of the LED image. Simulations showed that the average signal-to-noise ratio in our positioning system was 19.3 dB. The simulation results also showed that the root mean square positioning error was reduced from 6.6 to 3.7 cm when the resolution of the image sensor was 3000 pixels per cm, which is comparable to the error in the widely used M.S. Rahman’s algorithm. The distance between the centers of the lenses and the focal lengths of the lenses also affects the positioning error. After the simulations, the relationship between the positioning error and the lens distance or focal length is deduced. It is observed that this algorithm has lesser positioning errors than the M.S. Rahman’s algorithm.  相似文献   

17.
胡恒  杜小平  张朋  渠晋 《红外与激光工程》2018,47(10):1006004-1006004(7)
为减小传统激光测距方法中复杂电路系统对脉冲计时或相位比较引起的测距误差,针对偏振调制激光测距技术,利用电光调制器中晶体折射率随施加电场线性变化的特性,将待测物体反射的光脉冲调制成时间的函数,通过所得偏振光两个垂直方向上的光强比值求解待测距离。在研究其测距原理、距离方程及误差分析的基础上,推得文中测距方法所能达到理论测距精度的表达式,并分析调制过程中正弦、锯齿、指数三种调制函数对测距精度的影响,在相同距离范围内,锯齿函数具有更好的适用性,正弦函数与指数函数的组合函数具有更高的测距精度。进一步分析正弦函数不同波段对测距精度的影响可知,采用-/6~/6波段调制时其适用性及测距精度都有很大提高。研究结果对提高偏振调制激光测距精度具有重要意义。  相似文献   

18.
为了提高礼仪机器人在复杂环境中测量数据的可靠性以及解决同一类型多传感器测距盲区无法补偿的问题,使得礼仪机器人可以测得300cm以内障碍物的距离信息,本设计采用红外传感器和超声波传感器组成礼仪机器人的测距系统,并应用自适应加权数据融合技术对传感器所测数据进行融合,实现了两种传感器在功能上的互补,提升了系统的实时性,减小了系统的测距误差。实验结果表明系统可在300cm以内精确测距,提高了整体测距精度,得到了被测距离更加准确的估计。  相似文献   

19.
位置敏感探测器(PSD)是一种可以探测光斑重心位置的光学传感器,具有响应速度快、位置分辨率高和处理电路简单等优点,在角度测量、位置检测等精密测量系统中具有广泛的应用。介绍了在实验室内光学平台上搭建光路,选用A823数据采集卡,并在DOS操作系统Borland C++ builder环境下编写C程序连续实时采集模拟电压信号,实现AD转换,计算光斑位置坐标并进行误差分析。实验选用瑞典SiTek公司型号为2L10_SU65_SPC02的四边形位置敏感探测器,通过误差分析得出主要结论,包括PSD存在边缘效应,室内实验影响传感器位置坐标的主要因素是自然光和日光灯,去除影响因素后精度明显提高。  相似文献   

20.
针对位置已固定的双目立体装置,提出了一种基于非平行模式测距原理的双目系统光轴-光心参数标定方法,减小了光轴-光心位置误测量带来的测距误差;为解决低照度下双目立体视觉中存在的立体匹配误匹配点多、目标识别度低的问题,采取了最大熵法结合整体光强变化的阈值选取方法提取显著目标,提高了目标识别率,搭建了显著目标测距系统.结果表明:采用文中的系统标定与阈值选取方法的双目立体视觉装置在低照度下具有较高的测距精度及目标识别率.  相似文献   

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