An integrated front-end vertical hall magnetic sensor fabricated in 0.18 μm low-voltage CMOS technology

An integrated front-end vertical CMOS Hall magnetic sensor is proposed for the in-plane magnetic field measurement. To improve the magnetic sensitivity and to obtain low offset, a fully symmetric vertical Hall device (FSVHD) has been optimized with a minimum size design. A new four-phase spinning current modulation associated with a correlated double sampling (CDS) demodulation technique has been further applied to compensate for the offset and also to provide a linear Hall output voltage. The vertical Hall sensor chip has been manufactured in a 0.18 μm low-voltage CMOS technology and it occupies an area of 1.54 mm². The experimental results show in the magnetic field range from –200 to 200 mT, the entire vertical Hall sensor performs with the linearity of 99.9% and the system magnetic sensitivity of 1.22 V/T and the residual offset of 60 μT. Meanwhile, it consumes 4.5 mW at a 3.3 V supply voltage. The proposed vertical Hall sensor is very suitable for the low-cost system-on-chip (SOC) implementation of 2D or 3D magnetic microsystems.     

A silicon MOS magnetic field transducer of high sensitivity

A structure has been devised which converts magnetic flux density change to a change in output current. The structure is essentially a P-channel MOST with the drain diffusion split into two halves. A magnetic field normal to the silicon surface deflects device current towards one half-drain. By operating the MOST in the "pinched-off" mode (VDS> VGS-VT) the output impedance is made high, so that large output voltage swings may be obtained. A theoretical study of the voltage and current distributions in the MOST channel has given data on the influence of device geometry on sensitivity. Experimental results indicate a linear relationship between output current and magnetic flux density, and an unexplained nonlinear variation of output with device current. Comparison of experimental results with theory indicates a carrier Hall mobility in the channel of 116 cm²/V.s.     

Monolithic magnetic Hall sensor using dynamic quadrature offsetcancellation

The offset voltage and its temperature drift and production spread, which generally degrades the zero-level stability and reproducibility of magnetic Hall sensors, can be reduced using a single Hall plate and switching means for periodic permutation of the supply and output contact pairs. The present work describes a chopper-based 5-V monolithic linear Hall sensor with a ±0.1 T full scale where this dynamic plate offset cancellation technique has been employed together with a cost-effective signal conditioner. The device was integrated using a 2-μm conventional BiCMOS process and the final chip, measuring 15×1.5 mm², shows, after packaging in a 3-pin plastic package, a residual offset with a production spread and a temperature-induced drift five to ten times smaller than in currently used multiplate dc quadrature cancellation approaches. The device does not require external components and provides an output free of HF residues     

差分霍尔效应加速度测量方法及其线性实验模拟

对磁场中对称结构的霍尔元件的输出特性进行研究,提出一种差分霍尔效应加速度测量方法。基于线性霍尔元件和圆柱形永磁体设计加速度测量模型,两个霍尔元件与磁体构成对称互补结构,以差分方式输出信号电压。建立加速度与输出电压的线性关系,实现以非接触的方式测量加速度。模型的对称互补式设计,减小了非线性因素对测量的影响,改善了输出线性度。差分式电压输出,能够抑制共模干扰和零点漂移,并提高了信号幅度。对模型进行线性模拟实验,实验结果符合理论结论。数据分析显示,测量方法具有较高灵敏度和线性度。     

Measuring system for development of stroke-sensing cylinder forautomatic excavator

In order to develop a stroke-sensing cylinder for automatic excavators equipped with Hall sensors of GaAs type, a measuring test facility is set up and used in investigating the design parameters. The measuring system itself is a kind of XZ table with two moving axes in X and Z directions, respectively, on which sensing parts, including Hall sensors, are installed. Furthermore, to attain a high precision of movement of the measuring system, a new sliding mode control is introduced, which diminishes chattering in the control loop by setting two dead zones along the switching line. The unknown parameters for sliding mode control are estimated by a signal compression method. The output signal from a Hall sensor was analyzed by using a measuring instrument. In particular, the detected signal according to the Hall sensor's movement on the piston rod, which has a magnetic scale, was investigated and the vertical distance between the Hall sensor and the piston rod, which gives direct effects on the detected signal, was obtained. Based on these results, the stroke-sensing cylinder was designed and fabricated     

A 2D CMOS microfluxgate sensor system for digital detection of weakmagnetic fields

This paper presents a CMOS two-dimensional (2-D) vector magnetic sensor system integrating two planar microfluxgate sensors and the complete electronics for sensor excitation and signal readout. The system is based on an industrial 0.8-μm double-poly, double-metal CMOS technology with ferromagnetic NiFeMo cores added in a simple postprocessing sequence. The fluxgate sensors are embedded in a ΣΔ analog-to-digital converter for a stable and precise digital detection of weak magnetic fields. A cascaded ΣΔ modulator topology is utilized to obtain second-order noise shaping and to suppress pattern noise. Within the range of ±50 μT, the system nonlinearity is less than 1.5 μT. The angular resolution as a 2D vector sensor is less than 4° for a measured magnetic induction of 50 μT. This makes the 2-D microfluxgate magnetometer suitable for use as fully integrated electronic compass     

Highly sensitive Hall magnetic sensor microsystem in CMOStechnology

A highly sensitive magnetic sensor microsystem based on a Hall device is presented. This microsystem consists of a Hall device improved by an integrated magnetic concentrator and new circuit architecture for the signal processing. It provides an amplification of the sensor signal with a resolution better than 30 μV and a periodic offset cancellation while the output of the microsystem is available in continuous time. This microsystem features an overall magnetic gain of 420 V/T     

Magnetic-field-sensitive multicollector n-p-n transistors

A recently introduced type of magnetic-field-sensitive silicon microtransducer is described. These devices consist of a multicollector n-p-n transistor fabricated with standard integration techniques. The dependence of output signals on bias conditions, which influence the emitter and collector-current distribution, is analyzed theoretically for both two- and four-collector structures. These one- and two-dimensional vector sensors have been fabricated and tested. The experimental results are compared qualitatively with the theory. Theory and measurements indicate that the two-collector structure gives a differential collector-output current, which is linearly proportional to a magnetic induction, applied along one axis only. Theory and measurements also indicate that the vector sensor gives output signals, which are a linear function of the two components of an in-plane magnetic-induction vector. Consequently, this device is capable of measuring the magnitude and direction of such a vector.     

Teleoperation of a Mobile Robot Using a Force-Reflection Joystick With Sensing Mechanism of Rotating Magnetic Field

Operators’ intelligent and skillful decisions are necessary for the teleoperation of a mobile robot when there are many scattered obstacles. Among the sensors used for environment recognition, the camera is the most popular and powerful. However, there are several limitations in the camera-based teleoperation of a mobile robot. For example, shadowed and curved areas cannot be viewed using a narrow view-angle camera, especially in an environment with bad illumination and several obstacles. Therefore, it is necessary to have other sensory information for reliable teleoperations. In this study, 16 ultrasonic sensors are attached around a mobile robot in a ring pattern to measure the distances to the obstacles and a collision vector is introduced as a new tool for obstacle avoidance, which is defined as the normal vector from an obstacle to the mobile robot. Based on this collision vector, a virtual reflection force is generated to avoid the obstacles and then the reflection force is transferred to the operator who is holding the joystick used to control the mobile robot. Based on this reflection force, the operator can control the mobile robot more smoothly and safely. For this bidirectional teleoperation, a master joystick system using a two-axis hall sensor was designed to eliminate the nonlinear region, which exists in a general joystick with two motors and potentiometers. The effectiveness of the collision vector and force-reflection joystick is verified by comparing two vision-based teleoperation experiments, with and without force reflection.      

一种新型的磁悬浮轴承磁场均匀性测试仪

设计了一种由微处理器控制的新型的磁悬浮轴承均匀性测试仪,采用集成霍尔传感器获得磁感应强度的信号,采用AD574完成信号的采集,微处理器采用STC89C51X系列,对测量的结果进行采用独立的模块进行显示和存储。由于霍尔传感器和放大器均为线性元件,整个系统的线性度较高,测量误差可以控制在测量最大值的2%左右。     

Magnetostrictive torque sensor performance-nonlinear analysis

The effects on performance of magnetostrictive torque sensors due to nonlinear properties of magnetic materials are analyzed. A solution for the nonlinear problem is described. For constant magnetomotive force (constant current) excitation, nonlinear effects dramatically reduce the predicted output signal of the sensor from that computed using linear models. Saturation and the subsequent fall-off of a sensor signal as excitation current is increased are predicted and agree well with experimental results. The sensor signal continually increases with the increase of excitation frequency. As is shown, this gain must be balanced against growing problems of sensor signal-to-noise ratio, surface-localized noise, and requirements for higher-power/higher-voltage excitation sources     

A Decoupled Approach for Near-Field Source Localization Using a Single Acoustic Vector Sensor

This paper considers the problem of three-dimensional (3-D, azimuth, elevation, and range) localization of a single source in the near-field using a single acoustic vector sensor (AVS). The existing multiple signal classification (MUSIC) or maximum likelihood estimation (MLE) methods, which require a 3-D search over the location parameter space, are computationally very expensive. A computationally simple method previously developed by Wu and Wong (IEEE Trans. Aerosp. Electron. Syst. 48(1):159–169, 2012), which we refer to as Eigen-value decomposition and Received Signal strength Indicator-based method (Eigen-RSSI), was able to estimate 3-D location parameters of a single source efficiently. However, it can only be applied to an extended AVS which consists of a pressure sensor separated from the velocity sensors by a certain distance. In this paper, we propose a uni-AVS MUSIC (U-MUSIC) approach for 3-D location parameter estimation based on a compact AVS structure. We decouple the 3-D localization problem into step-by-step estimation of azimuth, elevation, and range and derive closed-form solutions for these parameter estimates by which a complex 3-D search for the parameters can be avoided. We show that the proposed approach outperforms the existing Eigen-RSSI method when the sensor system is required to be mounted in a confined space.     

自适应双参考磁场梯度探测原理

本文使用4个单分量磁探头构成双参考磁场梯度探测装置.4个探头组成3个磁场梯度传感器,其中一个为信号传感器,另两个为噪声传感器.以信号传感器输出作为原始输入,噪声传感器输出作为参考输入,采用自适应噪声抵消技术,能有效消除因载体运动产生的涡流磁场及因磁探头方向相对地磁方向改变而引起的噪声输出.本文提出的双参考磁场梯度探测装置具有工艺性好,灵敏度高,虚警概率低的优点,可在实际磁探系统中使用.     

光纤电压传感器的温度跟踪补偿

分析了光纤电压传感器的温度特性 ,表明测量范围较宽时 ,传感器的输出易受环境温度的影响 ,并且呈非线性。提出一种基于人工神经网络的光纤电压传感器温度跟踪补偿方法。利用神经网络具有逼近任意非线性函数的特点 ,通过训练使神经网络建立在不同环境温度下传感器输出与其实际感受的电压值之间的非线性映射关系 ,实现光纤电压传感器温度全程跟踪补偿。计算机仿真表明 ,该方法不仅能有效地消除温度的影响 ,而且能在神经网络的输出端得到期望的线性输出。     

Nonlinear phase correction with an extended statistical algorithm

This paper presents a new magnetic resonance imaging (MRI) phase correction method. The linear phase correction method using autocorrelation proposed by Ahn and Cho (AC method) is extended to handle nonlinear terms, which are often important for polynomial expansion of phase variation in MRI. The polynomial coefficients are statistically determined from a cascade series of n-pixel-shift rotational differential fields (RDFs). The n-pixel-shift RDF represents local vector rotations of a complex field relative to itself after being shifted by n pixels. We have found that increasing the shift enhances the signal significantly and extends the AC method to handle higher order nonlinear phase error terms. The n-pixel-shift RDF can also be applied to improve other methods such as the weighted least squares phase unwrapping method proposed by Liang. The feasibility of the method has been demonstrated with two-dimensional (2-D) in vivo inversion-recovery MRI data.     

Design of linear combination of weighted medians

This paper introduces a novel nonlinear filtering structure: the linear combination of weighted medians (LCWM). The proposed filtering scheme is modeled on the structure and design procedure of the linear-phase FIR highpass (HP) filter in that the linear-phase FIR HP filter can be obtained by changing the sign of the filter coefficients of the FIR lowpass (LP) filter in the odd positions. The HP filter can be represented as the difference between two LP subfilters that have all positive coefficients. This representation of the FIR HP filter is analogous to the difference of estimates (DoE) such as the difference of medians (DoM). The DoM is essentially a nonlinear HP filter that is commonly used in edge detection. Based on this observation, we introduce a class of LCWM filters whose output is given by a linear combination of weighted medians of the input sequence. We propose a method of designing the 1-D and 2-D LCWM filters satisfying required frequency specifications. The proposed method adopts a transformation from the FIR filter to the LCWM filter. We show that the proposed LCWM filter can offer various frequency filtering characteristics including “LP,” “bandpass (BP),” and “HP” responses     

Magnetic backprojection imaging of the vascular lumen

Current injected into a phantom model generated a magnetic field which was distorted above a simulated atherosclerotic lesion. The output of a Hall effect magnetic sensor was used in a backprojection to reconstruct the centroid of the simulated blood flow and thus localize the modeled atherosclerotic plaque region     

A CMOS image sensor for high-speed active range finding using column-parallel time-domain ADC and position encoder

In this paper, a smart image sensor for real-time and high-resolution three-dimensional (3-D) measurement to be used for sheet light projection is presented. It realizes not only a sufficiently high frame rate for real-time 3-D measurement, but also high pixel resolution due to a small pixel circuit and high subpixel accuracy due to gravity center calculation using an intensity profile. Simulation results show that the ultimate frame rate is 32.6 k frames/s (i.e., 31.8 range/spl I.bar/map/s) in a 1024/spl times/1024 pixel sensor. A 3-b intensity profile allows subpixel accuracy under 0.1 pixel. The sensor using this architecture can acquire a two-dimensional (2-D) image as well, so a texture-mapped 3-D image can be reproduced by the same sensor. A 128/spl times/128 smart image sensor has been developed and successfully tested. A 2-D image, a range map, and a texture-mapped 3-D image have been acquired by the 3-D measurement system using the fabricated sensor.     

CMOS 2D Hall microsensor with minimal design complexity

A new silicon integrated 2D Hall sensor for high-accuracy magnetic-field in-plane vector measurements fabricated through a CMOS technology, has been suggested and tested. Its unique advantage is minimal design complexity: only four external connections, lack of cross-sensitivity between the channels and very high resolution. In addition, a simple, but highly effective circuitry fully compensates for the offsets and the nonlinear magnetoresistance of the two outputs     

Vector-sensor array processing for electromagnetic sourcelocalization

The authors present a new approach for localizing electromagnetic sources using sensors where the output of each is a vector consisting of the complete six electric and magnetic field components. Two types of source transmissions are considered: (1) single signal transmission (SST), and (2) dual signal transmission (DST). The model is given in terms of several parameters, including the wave direction of arrival (DOA) and state of polarization. A compact expression is derived for the Cramer-Rao bound (CRB) on the estimation errors of these parameters for the multi-source multi-vector-sensor model. Quality measures including mean-square angular error (MSAE) and covariance of vector angular error (CVAE) are introduced, and their lower bounds are derived. The advantage of using vector sensors is highlighted by explicit evaluation of the MSAE and CVAE bounds for source localization with a single vector sensor. A simple algorithm for estimating the source DOA with this sensor is presented along with its statistical performance analysis