虚拟传声器的有源噪声控制

研究虚拟传声器的有源噪声控制问题。该技术适用于控制区域不适合放置误差传声器的场合。将误差传声器置于控制区域之外,得到测量误差。采用前向差分预测算法预测控制区域内的残余误差信号,然后利用自适应LMS算法,得到最优的噪声控制滤波器。为了尽量消除预测中存在的误差,采用自适应变权值预测算法。仿真结果表明该方法能有效地抑制噪声,使控制区域内的噪声信号得到明显衰减。     

Precision pointing of imaging spacecraft using gyro-based attitude reference with horizon sensor updates

Remote sensing satellites are required to meet stringent pointing and drift rate requirements for imaging operations. For achieving these pointing and stability requirements, continuous and accurate three-axis attitude information is required. Inertial sensors like gyros provide continuous attitude information with better short-term stability and less random errors. However, gyro measurements are affected by drifts. Hence over time, attitudes based on the gyro reference slowly diverge from the true attitudes. On the other hand, line-of-sight (LOS) sensors like horizon sensors provide attitude information with long-term stability. Their measurements however are affected by the presence of random instrumental errors and other systematic errors. The limitations of inertial and line-of-sight sensors are mutually exclusive. Hence, by optimal fusion of attitude information from both these sensors, it is possible to retain the advantages and overcome the limitations of both, thereby providing the precise attitude information required for control. This paper describes an improved earth-pointing scheme by fusion of the three-axis attitude information from gyros and horizon sensor roll and pitch measurements along with yaw updates from the digital sun sensor. A Kalman Filter is used to estimate the three-axis attitude by online estimation and corrections of various errors from the sensor measurements. Variations in orbit rate components are also accounted for using spacecraft position and velocity measurements from the satellite positioning system. Thus precise earth-pointing is achieved     

基于球杆仪和光栅尺的工作台精度调整

用球杆仪和光栅尺同时测量了两轴联动精密工作台的走圆运动．结果显示,光栅尺的主要误差源是测量噪声和定位误差,球杆仪的主要误差源是定位误差．尽管对于单轴实时位置反馈来说,光栅尺的测量精度已经足够,但是两个方向光栅尺的测量数据不能反映两轴间的相对精度．通过对光栅尺和球杆仪测量的工作台走圆运动测量数据的分析,建立了测量系统的数学模型,在此基础上解耦并识别出了球杆仪和光栅尺的定位误差．提出了根据光栅尺倾角误差实现工作台精度调整的策略．     

Responses of simple optical standing wave sensors

Optical standing wave sensors have been manufactured by amorphous silicon deposition. The responses of these sensors, when subjected to standing waves, have been calculated and measured. It is shown that the responses are different depending on the way the standing wave is created. The responses also depend on the thickness and material properties of the layers used to create the sensors. Quantitative agreement between measurements and model calculations can be obtained by including alignment errors, incoherent light interaction and scaling factors. The simple construction of the sensors allows for a broad application range.     

Measurement accuracy in control of segmented-mirror telescopes

Design concepts for future large optical telescopes have highly segmented primary mirrors, with the out-of-plane degrees of freedom actively controlled. We estimate the contribution to errors in controlling the primary mirror that results from sensor noise and, in particular, compare mechanical measurements of relative segment motion with optical wave-front information. Data from the Keck telescopes are used to obtain realistic estimates of the achievable noise due to mechanical sensors. On the basis of these estimates, mechanical sensors will be more accurate than wave-front information for any of the telescope design concepts currently under consideration, and therefore supplemental wave-front sensors are not required for real-time figure control. Furthermore, control system errors due to sensor noise will not significantly degrade either seeing-limited or diffraction-limited observations.     

动态力校准中力传感器端部等效质量测量方法研究

力传感器端部等效质量是动态力校准中的重要部分,其测量误差会对动态力校准产生较大影响。本文通过了解力传感器结构,确定力传感器端部等效质量的构成,并简单介绍了四种测量端部等效质量的方法。最后,利用两次配重消去法进行实验,将不同配合不同工况下得到的结果进行对比分析,说明该方法可以较好的解决测量端部等效质量问题。     

Bandpass-resampling effects for the retrieval of surface emissivity

The retrieval of surface emissivity in the 8-14-microm region from remotely sensed thermal imagery requires channel-averaged values of atmospheric transmittance, path radiance, and downwelling sky flux. Band-pass resampling introduces inherent retrieval errors that depend on atmospheric conditions, spectral region, bandwidth, flight altitude, and surface temperature. This simulation study is performed for clear sky conditions and moderate atmospheric water vapor contents. It shows that relative emissivity retrieval errors can reach as much as 3% for broadband sensors (1-2-microm bandwidth) and 0.8% for narrowband instruments (0.15 microm), even for constant surface emissivity. For spectrally varying surface emissivities the relative retrieval error increases for the broadband instrument by approximately 2% in channels with strong emissivity changes of 0.05-0.1. The corresponding retrieval errors for narrowband sensors increase by approximately 3-4%. The channels in the atmospheric window regions with lower transmittance, i.e., 8-8.5 and 12.5-14 microm, are most sensitive to retrieval errors.     

Phase-demodulation error of a fiber-optic Fabry-Perot sensor with complex reflection coefficients

The influence of reflector losses attracts little discussion in standard treatments of the Fabry-Perot interferometer yet may be an important factor contributing to errors in phase-stepped demodulation of fiber optic Fabry-Perot (FFP) sensors. We describe a general transfer function for FFP sensors with complex reflection coefficients and estimate systematic phase errors that arise when the asymmetry of the reflected fringe system is neglected, as is common in the literature. The measured asymmetric response of higher-finesse metal-dielectric FFP constructions corroborates a model that predicts systematic phase errors of 0.06 rad in three-step demodulation of a low-finesse FFP sensor (R = 0.05) with internal reflector losses of 25%.     

Correction of Systematic Errors of Ratiometric Measurement Transducers

New methods are considered for correcting additive and multiplicative systematic errors of ratiometric measurement transducers utilizing sensors whose output signal u(x) is proportional to their power supply voltage or current. It is shown that synthesized algorithms for processing the intermediate results of measurements provide a reduction in the additive errors by several orders of magnitude and almost completely eliminate multiplicative errors.     

飞机环控系统管道气流温度的测量

根据实际使用中出现的问题，对各种实用的管道气流温度传感器的误差进行了计算，对电阻式和热电偶式温度传感器的误差原因作了定量分析。由于带密封罩的温度传感器在实际使用中存在着明显的缺点，建议今后使用热电偶测量飞机环控系统管道气流温度，并提出了一种实用热电偶温度传感器的结构形式，同时也介绍了如何减小由于热传导和热辐射引起的误差。     

Linearization of calibration characteristics of capacitance pressure sensors

The nonlinearity of the calibration characteristics of capacitance pressure sensors and the approximation of these characteristics by means of various analytic functions are considered. The resulting approximation errors are estimated. A method and algorithm for digital linearization of the calibration characteristic of a sensor with the use of a cubic spline are proposed.     

三测头同方位同步测量实时分离轴系回转误差

本提出的三测头同方位同步测量衬时分离轴系回转误差的新方法,能在一次测量过程中将系回转误差的系统误差和随机误差一并分离,可提高测量准确度几倍至几十倍。     

CAN总线的机器人传感器网络设计

研发了基于CAN总线的移动机器人传感器网络,有效地保证了移动机器人多传感器信息通讯的实时性和稳定性.详细阐述了该移动机器人的体系结构和传感器网络的组成,同时设计了一套CAN网络通讯协议,实现了传感器节点的多主通讯,在很大程度上改进和提高了移动机器人的性能.     

主动测量信息的智能化处理与控制

主动测量仪正朝着智能化和多参数测量的方向发展,传感器检测信号的滞后特性是产生动态误差的主要原因,本文提出了一种对被测信息进行智能化处理的方法,通过在线辨识传感器滞后时间常数Ｔｍ,再利用校正（补偿）的方法减少或消除滞后时间常数Ｔｍ的影响,从而减少或消除动态误差,实现测量与控制熔为一体、主动测量技术的自动化。     

Compensating for Thermal Size Change in Platforms for Gyroscopes and Laser Angle Sensors

Devices are described for compensating the thermal size change in platforms for gyroscopes and laser rotation angle sensors that employ various optical systems. Ways are considered of reducing the measurement errors and improving the resolving power.     

Optimal selection of commercial sensors for linear model representation of daylight spectra

The average spectral power distribution of a set of measured daylight spectra, E(av)(lambda), is used for preliminary screening to select optimal sensor sets for daylight recovery. Spectra quite different from E(av)(lambda) are applied to the screened sets to obtain minimum total spectral error, which is closely related to recovery metrics but not to the coefficient of error. All basis functions should be utilized to make these two errors equal, to predict precisely the best sensor set, and to extend a set of few sensors to a set of many sensors. These are not acquirable by an exhaustive full search method.     

利用抽样率变换提高渡越时间测量精度方法

为了克服低采样率对信号渡越时间测量精度的影响,提出一种互相关与抽样率变换相结合的渡越时间估计方法.首先对上下游传感器信号进行采样率变换,然后对它们进行傅立叶变换;并通过低通滤波器滤除多余的镜像,最后根据卷积定理求出上下游传感器信号的相关函数和渡越时间.仿真实验结果表明:文章方法得到的渡越时间估计值误差比较小,结果更可靠...     

A Novel Miniature Four-Dimensional Force/Torque Sensor With Overload Protection Mechanism

Force sensors play a key role in modern technology. Specifically, they can measure the force of mechatronics systems used in automated manufacturing environments, thereby enabling such systems to function effectively, thus facilitating decision making. However, the most current generation of force and torque sensors is complicated and expensive. Moreover, these sensors cannot be used for many applications because they are too brittle to sustain a large load. Accordingly, this paper presents a novel miniature four-dimensional force sensor, whose element is in the form of an E-type membrane connected to double rectangle slices. This sensor is aimed at obtaining the accurate interaction forces, including the normal force, both tangential force terms and the torque about the normal axis, in most applications. Furthermore, the sensor contains the advantages of configuration simplicity, overload protection and high sensitivity. Experiment results demonstrate its strong linearity, weak couplings among dimensions and simple calibration. The maximum nonlinearity errors is 0.18% F.S. and the maximum interference errors is 1.9% F.S.      

高精度电容测微仪的自校正方法

本详细叙述了一种电容测微仪的自校正方法,并就其工作原理进行了讨论。采用这 方法不需要其它高精度标准,仅利用两相同精度的电容传感器和自校正装置即可进行多次相互校准,最终得到各自准确度达到自身能力极限的校正结果。     

Acoustic emission source localization technique based on least squares support vector machine by using FBG sensors

An intelligent acoustic emission (AE) source localization technique by using fiber Bragg grating (FBG) sensors was investigated. Four FBGs sensing network was established for detecting the AE signal. And power intensity demodulation method was initialized employing narrow-band tunable laser. The intelligent AE source localization method was proposed based on wavelet transform, cross-correlation analysis, and least squares support vector machines (LS-SVM). LS-SVM modal’s input is signal time difference and output is AE source position. The location experiments were carried out on a 500 mm × 500 mm × 2 mm aluminum alloy plate. The results showed that the AE source position abscissa and ordinate localization errors are all less than 10 mm. The maximum and average localization errors are 8.65 and 6.78 mm, respectively. The research results provided a novel method for AE source localization by using FBG sensors.