Algorithms for optimal scheduling and management of hidden Markovmodel sensors

The author considers a hidden Markov model (HMM) where a single Markov chain is observed by a number of noisy sensors. Due to computational or communication constraints, at each time instant, one can select only one of the noisy sensors. The sensor scheduling problem involves designing algorithms for choosing dynamically at each time instant which sensor to select to provide the next measurement. Each measurement has an associated measurement cost. The problem is to select an optimal measurement scheduling policy to minimize a cost function of estimation errors and measurement costs. The optimal measurement policy is solved via stochastic dynamic programming. Sensor management issues and suboptimal scheduling algorithms are also presented. A numerical example that deals with the aircraft identification problem is presented     

曲率光纤传感器的智能夹层系统研究

根据光纤自诊断系统模块化、集成化要求,将曲率光纤传感器以环形布置在PE膜的对称两面,研制了一种智能夹层系统,它可以同时测量结构的曲率和扭转。提出了智能夹层系统的标定方法。对埋有光纤智能夹层的玻璃纤维增强树脂基复合材料试件在CMT6305型电子万能试验机上进行了轴向拉伸、压缩试验和三点式弯曲性能试验,结果表明,智能夹层的埋入对智能结构力学性能有一定的影响,但影响不大。将光纤智能夹层埋入复合材料内部进行了结构曲率测试,在埋入过程中,光纤传感器的完好率达100%。与埋入前的标定结果相比,智能夹层在埋入后的曲率测量最大偏差为5.2%,说明光纤智能夹层可以在埋入复合材料之前进行标定。     

Calibration of resistance type die level temperature sensors usinga single temperature technique

Thermal test chips are widely used to develop electronic packaging thermal solutions and to evaluate electronic package assembly processes. Temperature sensors are an integral component on thermal test chips. Unfortunately, each temperature sensor must be calibrated in order for them to be effective. Each calibration can take up to one hour to complete. In a time when increasing sample sizes and shorter development cycles are taxing current equipment and manpower resources, new calibration techniques must be established to keep development costs down. This paper discusses simplified calibration procedures, which can significantly reduce the time needed for temperature sensor calibration. The simplified calibration procedures utilize single-resistance measurements either at room temperature or at the anticipated test temperature. For four different test chip designs included in the current study, calibration error variations less than ±0.6°C at a ±2σ confidence level are possible. The simplified calibration procedures can be applied to any resistor type temperature sensor that has a linear correlation between its electric resistive properties and temperature     

多星敏感器地面热漂移标定位置误差检测研究

为了减少多个星敏感器地面热漂移标定时受到不同安装平台的位置误差影响, 采取一种多星敏感器地面热漂移标定位置误差检测方法,进行了理论分析和实验验证,取得了-25℃~60℃真空状态下系统中基准方棱镜变形的位置偏移量数据,并进行了标定位置误差精度分析。结果表明,多星敏感器位置绕各轴产生的最大偏移量分别为-39.341″/℃, -0.060″/℃, -24.137″/℃,通过建立误差检测模型对位置误差进行计算,将其从姿态测量结果的偏移量中剔除后获得更准确的星敏感器姿态测量四元数,剔除位置误差后的系统精度至少提高了11%。该研究在提高星敏感器热漂移标定精度方面具有很好的应用前景。     

光纤光栅和静态电阻在静压模型管桩测试中的对比试验研究

为了提高光纤布拉格光栅(fiber Bragg gratin g,简称FBG)应变传感器测量精度,针对光纤光栅传 感器在模型管桩试验应用情况,提出了一种光纤光栅传感器理论灵敏度系数和实验灵敏度系 数应变标定方 法。该方法通过实验标定微型光纤光栅应变传感器的灵敏度系数,与理论分析传感器灵敏度 系数进行对比, 同时在模型管桩安装传感器位置粘贴应变片。实验结果表明,标定后的FBG应变传感器测试 结果更加准确, 为基于FBG应变传感器的模型管桩监测技术奠定了基础。同时,该方法适用于FBG传感器应 用与模型管 桩前的标定,可以得到准确反映模型管桩受力变形的真实数据,提高了光纤光栅传感器在模 型管桩试验中 的测量精度。同时,该方法简单、易操作,为光纤光栅传感器在试验和工程中应用奠定了基 础,加快了FBG 传感器在模型管桩荷载传递监测应用的步伐。     

A time-to-digital-converter-based CMOS smart temperature sensor

A time-to-digital-converter-based CMOS smart temperature sensor without a voltage/current analog-to-digital converter (ADC) or bandgap reference is proposed for high-accuracy portable applications. Conventional smart temperature sensors rely on voltage/current ADCs for digital output code conversion. For the purpose of cost reduction and power savings, the proposed smart temperature sensor first generates a pulse with a width proportional to the measured temperature. Then, a cyclic time-to-digital converter is utilized to convert the pulse into a corresponding digital code. The test chips have an extremely small area of 0.175 mm/sup 2/ and were fabricated in the TSMC CMOS 0.35-/spl mu/m 2P4M process. Due to the excellent linearity of the digital output, the achieved measurement error is merely -0.7/spl sim/+0.9/spl deg/C after two point calibration, but without any curvature correction or dynamic offset cancellation. The effective resolution is better than 0.16/spl deg/C, and the power consumption is under 10 /spl mu/W at a sample rate of 2 samples/s.     

表面式FBG应变传感器及其在高速公路桥梁工程中的应用

报道一种表面安装式光纤布喇格光栅(FBG)应变传感器及其在高速公路高架桥的车辆载荷压力试验中的应用。提出了一种具备应变放大能力且可调节的不锈钢封装的应变感测弹性结构,布设有FBG的弹性圆筒结构位于传感器中间部分,其横截面积小于传感器其他部分,传感器的应变测量放大系数可通过改变圆筒结构的长度和横截面积来调节。将24个经过测试标定后的应变传感器和6个FBG温度补偿传感器安装在甬台温高速吊水沿大桥箱梁底部,并对大桥实施一系列车辆载荷作用下的静态和动态试验,传感器表现出了良好的测量能力,3种静态载荷工况下的桥梁底部应变大小以及3种动态载荷工况下的应变变化情况被清晰地展现出来,理论分析与实验结果一致。     

基于24位置的MEMS惯性传感器快速标定方法

针对微惯性测量单元原始输出信息受零偏、标度因数、非正交误差等误差项干扰影响测量精度的问题,提出一种无需借助高精度转台的MEMS IMU快速原位标定方案。在分析MEMS惯性传感器输出特性的基础上建立传感器误差模型,利用六面体夹具设计IMU 24位置连续转停标定方案,以重力及各次旋转角度为参考信息完成传感器误差标定。针对加速度计零偏、标度因数、非正交误差9个参数构造标定模型,采用牛顿法估计误差参数最优值,考虑陀螺仪零偏与标度因数6个误差参数,利用最小二乘法计算误差参数最优估值。分别进行加速度计、陀螺标定补偿实验,实验结果表明,提出的MEMS IMU快速原位标定方法能快速得到传感器误差参数,提高了输出数据精度。     

One summer at NASA's John C. Stennis Space Center

The test stands at SSC are enormous structures, each with several hundred - even thousands - of sensors. With such a high sensor count and variety it is incredibly difficult to do anything useful with the influx of data in real time beyond recording it for future examination. However, it would be ideal if the test controller could not only view all of the data in an intuitive and information rich environment but also have the complementary sensor data fused together to provide more robust information. Enter the integrated intelligent health management system (IIHMS). The IIHMS is a collection of smart sensors, each aware of the local process they are measuring, controlled by an expert system with a global view of the entire system. The long-range goal is to develop an expert system to provide the test controller with a fully immersed environment in which to monitor the condition of every system component and receive advice on anomalies and proper courses of action. The IIHMS is now termed intelligent system health management (ISHM). Dave was assigned the hardware design of a smart temperature sensor that would form the foundation layer of the IIHMS; Don was responsible for the firmware that would add the intelligence to Dave's hardware by enabling it to monitor the health (i.e., quality) of the sensor and the quality of measurements in real time; Jon was left the task of designing the link between the smart sensor and the expert system. This work discusses the summer experience of the authors at SSC.     

基于自适应学习的多传感器融合时间管理

由于多传感器测量不同步,需要将各传感器时间校准到融合时间;以往采用的时间管理方法应用条件有限,且带入了较大的校准误差;为了减小校准误差,在内插和外推预测算法的基础上,引入自适应学习控制算子,利用学习算子的适应性能力调节估计参数;并利用时间序列预报,将内插和外推两个相反方向的估计值进行加权,进一步减小校准误差.最后以目标位置测量为例,对该方法进行仿真验证.     

Reducing Aging Impacts in Digital Sensors via Run-Time Calibration

Hazards or intentional perturbations must be identified in safety- and security-critical applications. Digital sensors have been shown to be an appealing approach to detect such abnormalities. However, as any sensor technology, digital sensors are prone to mis-calibration. In particular, even if the digital sensor initial calibration is correct, the rate of false and missed alarms might increase when the sensor is aged. In this paper, we thoroughly study the impact of aging-induced false and missed alarms. Indeed aging relates to the usage time, and a priori model (historical data for environmental variation) for predicting the aging is unrealistic for digital sensors as tracking the usage time with related temperature and voltage variation imposes high overhead. Accordingly, we propose an alternative approach where not one but two sensors are deployed. In practice, one sensor is used to detect environmental deviations, while the second one is used as the reference. In this respect, the second sensor is only operated seldom, mostly to re-calibrate the active sensor when aged. From this dual input (unaged and aged sensor), corrective models are derived. We account for two methods, namely simple but effective offset correction, and adjustment based on machine-learning. We conduct extensive characterizations (both pre-silicon simulations and post-silicon measurements on FPGA) which quantitatively confirm the applicability and high sensitivity of digital sensors.

     

检测多传感器标定失效的方法

为了提高智能车观测周围的环境的能力,其感知系统采用多传感器融合技术已经成为一种共识。采用多传感器融合技术可以对环境目标的位置进行融合,核心在于时间和空间对齐,其中空间对齐高度依赖于传感器的标定参数。由于车辆行驶过程的恶劣环境,传感器的标定参数会有失效的风险,从而使空间融合失败。因此,本文提出了一种检测多传感器标定失效的方法,提高智能车的安全性。     

微型四旋翼无人机磁测系统误差的两步校准法研究

用于地磁测量的MEMS三轴磁阻传感器越来越普遍的应用到无人机上进行姿态测量,为提高磁测系统的测量精度需要对传感器误差进行分析和补偿。现采用了一种两步校准法,即首先利用基于最小二乘的椭球假设拟合法对三轴矢量磁传感器的零偏、灵敏度与不正交误差进行标定补偿,目的是得到准确正交的传感器坐标系;利用四位置法对标定后传感器坐标系与测量系统坐标系之间的安装误差进行校准,从而得到磁测系统坐标系下的准确测量数据。无磁转台实验表明：经两步法后测量的磁场模值误差均值由校准前的2900nT降低为900nT,校准效果明显;测量系统单轴（Z轴）的误差均值由2736nT降低为49nT,有效的验证了安装误差校准的正确性。通过实验数据比较得出此方法优于传统的摇摆法,实际操作简单,不需要高精度辅助设备,能够有效的应用于无人机姿态测量系统校准,提高姿态角解算精度。     

Asynchronous particle filter for tracking using non-synchronous sensor networks

This paper deals with the problem of tracking using a sensor network when the sensors are not synchronised. We propose a new algorithm called the asynchronous particle filter that, with much less computational burden than the traditional particle filter, has a slightly poorer performance. Thus, it is a good solution to real-time applications with non-synchronised sensors when high performance is required. The low computational burden of the method lies in the fact that we do not predict and update the state every time a measurement is collected. Its high performance is due to the fact that we account for the time instant at which each measurement was taken.     

线结构光三维测量系统扫描方向的标定

提出一种基于平面标靶的线结构光三维传感器扫描方向的标定方法。利用平面标靶对摄像头进行标定,得到摄像头的内部参数,将棋盘格平面标靶固定在空间某一位置,测量系统沿着扫描方向移动并采集一系列图像。根据这一系列图像求出摄像机的外部参数,并结合已经求出的摄像机内部参数计算出标靶上同一特征点在摄像机坐标系下的坐标值,对这些点进行直线拟合得到一直线方程,直线的方向就是测量系统的扫描方向。实验表明,该方法测量精度高,操作简单,无需辅助的调整设备,降低了标定设备的成本和系统校准的难度,适合现场标定。     

Fault tolerance in multisensor networks

Replicating sensors is desirable, not only to tolerate sensor failures, but to increase the average accuracy of the ensemble of replicated sensors beyond that obtainable with a single sensor. Such replication is used in a multi-sensor environment or in a distributed-sensor network. Following Marzullo (1990), the authors have modeled a continuous valued sensor as an interval of real numbers containing the physical value of interest. Given n sensors of which at most f can suffer arbitrary failures, this paper presents an efficient O(n·log(n)) fault-tolerant algorithm (J/FTA) whose output is reliable (guaranteed to contain the correct value at all times) and is fairly accurate when f1/₂(n+1)). The output of J/FTA can be either a single-interval or a set-of-intervals, depending on the nature of the multi-sensor environment. J/FTA can be used not only to detect all possibly-faulty sensors but to detect all sets (combinations) of possibly-faulty sensors. This paper proves the following results pertaining to the possibly-faulty sensors identified by J/FTA: the number of sets each containing f possibly-faulty sensors is at most (f+1); the number of sets each containing f or fewer faulty sensors is at most (2f+1); and the number of possibly-faulty sensors identified by J/FTA is at most 2f. These results help to: narrow the search to detect faulty sensors; bound the number of intervals needed to construct an accurate and reliable abstract sensor; and identify at least one correct sensor     

壳体电容式电子测压器动态校准系统的合理性研究

针对微型电子测压器在实测过程中受到环境因素影响比较大,且将测压器置于实炮内进行实测校准的理想校准方法成本高、周期长等问题,提出了一种电容式电子测压器的动态校准方法。该方法采用模拟膛压发生器对微型电子测压器进行准动态校准,分析动态校准系统组成和工作原理,通过对标准传感器的特性和环境相似性的分析表明,对电容式电子测压器进行应用环境下校准的测试系统是满足要求的,这种校准方法也能有效用于动态高压的测量。     

一种智能车寻迹算法的研究

智能车自动寻迹技术,是体现其智能水平的一个重要标志.在利用光电传感器寻迹技术中,光电传感器的排布及其算法尤为重要.文中设计了一种传感器阵列"伞"型布局方式,并提出了相应的PID控制算法.试验证明,用此算法即使在路面导引线复杂的情况下,也能很好的保证智能车沿正确的方向前进,同时保证了运行时的平稳性.     

MEMS传感器和智能传感器的发展

MEMS传感器和智能传感器可以被称为新时代传感器的典型代表,在智能化以及集成化方面体现出独特的优势。随着我国科学技术发展水平的提高,MEMS传感器和智能传感器也处于不断发展的过程中,同时应用的范围不断拓宽,为各行各业带来了极大的便利。文章对此展开分析。     

基于神经网络的传感器非线性误差校正方法

为对传感器进行非线性校正以进一步提高其测量精度,提出了基于神经网络的校正办法。理论分析了传感器非线性误差的复杂性,并以位移传感器标定为例,详细介绍了传感器非线性校正的过程和方法。采用了最小二乘拟合、BP神经网络以及RBF网络三种方法进行校正,设计并实现了RBF网络的校正模型。实验结果证明,RBF网络的校正方法比BP网络校正方法精度提高了约44%,其补偿效果更优,且其在传感器种类变化或环境影响较大的情况下比最小二乘拟合更具非线性补偿优势。