Analog Voltage Signal Research Articles

Development of wireless sensor node hardware for large-area capacitive strain monitoring

Conventional resistive-type strain sensing methods have limitations in large-area sensing due to their relatively small size. The soft elastomeric capacitive (SEC) sensor is a capacitance-based stretchable electronic strain sensor, which has shown distinct advantages for mesoscale sensing over conventional strain-based structural health monitoring (SHM) due to its wide surface coverage capability. While recent advances in wireless sensor technologies have provided an attractive alternative to wired and centralized SHM, the capacitive strain sensing methods have not benefitted from the wireless approaches due to the lack of appropriate hardware element. This study develops a wireless sensor board to use the SEC sensor in combination with a wireless sensor network for SHM by addressing key implementation challenges. An alternating current (AC)-based De-Sauty Wheatstone bridge circuit is employed, converting dynamic capacitance variation from the SEC sensor into analog voltage signal. A high-precision bridge balancer and two-step signal amplifiers are implemented to effectively apply for low-level structural strain vibrations. An amplitude modulation-demodulator has been designed to extract the baseband signal (i.e. strain signal) from the carrier signal (i.e. AC excitation for the Wheatstone bridge). And a dual-step shunt calibrator has been proposed to remove the parasitic capacitance effect of lead wires during on-board calibration process. The performances of the sensor board developed in this study have been validated via a series of lab tests, outperforming a conventional wired capacitance measurement system.

CHIMERA: A Field-Programmable Mixed-Signal IC With Time-Domain Configurable Analog Blocks

This paper presents a field-programmable mixed-signal IC named CHIMERA, for low-cost and rapid prototyping of mixed-signal systems. The proposed IC implements field-programmable analog functions with time-domain configurable analog blocks (TCABs). A single TCAB can be programmed to various analog circuits, including a time-to-digital converter, digitally-controlled oscillator, digitally-controlled delay cell, digital pulse-width modulator, and phase interpolator. The TCABs convey and process analog information using the frequency, pulse width, delay, or phase of digital pulses or pulse sequences, rather than using analog voltage or current signals for reduced susceptibility to attenuation and noise. The overall CHIMERA chip also includes arrays of configurable logic blocks (CLBs) and programmable arithmetic logic units (ALUs) for programmable digital functions. By programming the functionality of the TCAB, CLB, and ALU arrays and configuring the interconnects, the chip can implement various mixed-signal systems. A prototype IC fabricated with 65-nm CMOS technology demonstrates the versatile programmability of CHIMERA by being successfully operated as a 1-GHz phase-locked loop with a 12.3-psrms integrated jitter, as a 50-MS/s analog-to-digital converter with a 32.5-dB SNDR, and as a 1.2-to-0.7 V DC–DC converter with 95.5% efficiency.

Roll Stability Early Warning System Based on Tilt Sensor

In view of the over-speed phenomenon of heavy haul vehicles at high speed, the estimation of the effective range of the dynamic stability and inclination angle of the truck was carried out a rollover stability alarm system based on liquid pendulum angle sensor and virtual instrument software was developed. The working principle and data processing module of tilt sensor are discussed, through the data lines to output analog voltage signal transmitted to the vehicle electronic control unit. A control command is sent by the electronic control unit and sent to the driver via an alarm device, which enables the driver to control the speed in time, and so it reduces the risk of a rollover accident. The results show that the warning system is of good accuracy. The early warning system preventing malignant road traffic accidents has important social significance and actual application value for a safe vehicle.

A Low-Power Wireless Piezoelectric Sensor-Based Respiration Monitoring System Realized in CMOS Process

This paper presents a methodology of monitoring respiration pattern using piezoelectric transducer incorporating CMOS integrated circuits for signal processing and data transmission. As a proof of concept, the system has been tested by placing electrodes on human chest using adhesive hydrogel to detect the pulsatile vibration due to respiration. The system can be used either as a wearable device itself or alternatively can be attached to a jacket or a chest belt. The front-end transducer is a piezoelectric material-based sensor, which is comprised of a ferroelectric polymer named polyvinylidene-fluoride (PVDF). PVDF is also biocompatible, which makes the sensor suitable to be used as a wearable device. The charge produced by the sensor is converted to a proportional voltage signal with the help of a charge amplifier designed in a standard 130-nm CMOS process with eight metal and one poly layer. The analog voltage signal acquired from the charge amplifier is then converted into a digital signal using a reconfigurable pipelined analog-to-digital converter for ease of transmission. An impulse-radio ultra-wideband transmitter operating in the frequency range of 3.1–5 GHz is designed for wireless transmission of the data. The smaller footprint, lighter weight, wireless telemetry, and low-cost material along with the low-power integrated CMOS circuitry for signal processing and data transmission make the proposed system an attractive choice for stable respiration monitoring system.

Design and Fabrication of Low Cost Eddy Current Sensor for Position Control Applications

Background/Objectives: Eddy current sensors are noncontact displacement sensors of high resolution providing measurement of the absolute position or change in position of any electrically conductive target. They are most suitable in dusty, smoky, dirty industrial environments where most other sensors would fail. This paper presents a design method and fabrication of a low cost eddy current sensor used in real time servo-control feed-back in Active magnetic Bearing. Method/Statistical Analysis: The primary functional piece of the eddy-current sensor is the sensing coil. This is a coil of wire near the end of the sensor probe. This piece of coil forms a part of an oscillator circuit there by carrying an alternating current through it which creates an alternating magnetic field. This field creates an eddy-current to flow on the target material whose distance is to be measured. This variation in field is used to sense the distance to the target. The coil is encapsulated in plastic and epoxy and housed in threaded stainless steel housing. Findings: The designed sensor has a measuring range of 0-3 mm and displacement resolution of 7 microns at a speed of 20 kHz sampling rate. This sensor was designed for the purpose of servo control feed-back in Active Magnetic Bearing System for position control. In this feedback control system we have employed a novel method of using time to digital conversion which converts the time period of the eddy current sensor’s square wave signal into digital counts using the 32bit timer counter of the enhanced capture module available in Texas Instruments C2000 controller. The digital counts give us the direct displacement value that can be used as feedback to generate the required error signal in the PID control loop. Application: The output frequency of the sensor is in the range of 700 kHz. We scale down this signal to 20 KHz by using the built-in divide by counter in the C2000 controller before feeding it to the capture module to capture the time period in a 32bit timer counter. This method of time period to digital count converter or displacement measurement helps reduce noise and errors in signal processing usually associated with ADC chips which converts analog voltage signal to digital counts.

A 25 MHz crystal less clock generator with background calibration against process and temperature variation

This paper presents a crystal-less clock generator using an automatic process and temperature variation calibration technique. The crystal-less clock generator comprises a voltage-controlled oscillator (VCO), differential-input-single-output (DISO) circuit, and frequency-to-voltage converter (FVC). The VCO was developed using a four-stage differential ring oscillator to generate an output frequency of 25MHz. The DISO circuit ensures a full-swing output voltage swing of the clock generator and a 50% duty cycle. The output clock is integrated by the FVC circuit to generate an analog voltage signal to control the VCO's oscillation frequencies. The FVC can compensate and calibrate the VCO to provide a stable output frequency through the closed-loop system. The chip was fabricated using a 0.18µm standard CMOS process with a 0.9V supply voltage. The measured temperature coefficient was 513ppm/°C in the temperature range of −40°C to 125°C at a 25-MHz output frequency.

금속 부품의 결함 판단을 위한 고유 주파수 분석 시스템 개발

In this study, we developed a system to detect the various defects in the metallic objects using the phenomenon that the defects cause the changes of the natural resonant frequencies. Our system consists of a FFT Amp, an Auto Impact Hammer, a Hammer controller and a PC. Auto Impact Hammer creates vibrations in the metallic objects when tapped on the surface. These vibrational signals are converted to the voltage signals by an acceleration sensor attached to the metallic part surface. These analog voltage signals were fed into an ADC (analog-digital converter) and an FFT (fast fourier transform) conversion in the FFT Amp to obtain the digital data in the frequency domain. Labview graphical program was used to process the digital data from th FFT amp to display the spectrum. We compared those spectra with the standard spectrum to find the shifts in the resonant frequencies of the metal parts, and thus detecting the defects. We used PCB's acceleration sensor and TI's TMS320F28335 DSP (digital signal processor) to obtain the resolution of 2.93 Hz and to analyze the frequencies up to 44 kHz.

A photonic analog-to-digital converter using phase modulation and self-coherent detection with spatial oversampling.

We propose a new type of photonic analog-to-digital converter (ADC), designed for high-resolution (>7 bit) and high sampling rates (scalable to tens of GS/s). It is based on encoding the input analog voltage signal onto the phase of an optical pulse stream originating from a mode-locked laser, and uses spatial oversampling as a means to improve the conversion resolution. This paper describes the concept of spatial oversampling and draws its similarities to the commonly used temporal oversampling. The design and fabrication of a LiNbO(3)/silica hybrid photonic integrated circuit for implementing the spatial oversampling is shown, and its abilities are demonstrated experimentally by digitizing gigahertz signals (frequencies up to 18GHz) at an undersampled rate of 2.56GS/s with a conversion resolution of up to 7.6 effective bits. Oversampling factors of 1-4 are demonstrated.

Development and Application Road Testbench on Vehicle Hydraulic Power Steering System

In order to study operation characteristic of the hydraulic power steering (HPS) system, a data gathering system, based on the testbench, was designed to test HPS system operating on-road. By using various kinds of sensors, such as hydraulic pressure, fluid flow rate, steering torque, corner angle, angular velocity, vehicle speed, gyro sensors and so on, convert steering wheel angle, angular velocity, torque and other operation parameters into analog voltage signals, which provided to real-time data acquisition, storage and analysis. 11 physical quantities can be tested simultaneously, including steering system and operation parameters of vehicles. Different angular velocity of steering wheel speed and "S" shape road were tested on different vehicle speeds, and the result shows that the tests are in accordance with theoretical analysis, which proves the data gathering system's credibility.

Implementation of a Wireless Strain Collection Terminal

In order to resolve the problem of complex wire routing, reliability and lightning-proof difficulty in automatic monitoring system of water conservancy engineering, the paper proposes a volume-compact, easily connected wireless strain collector. The collector modulates the differential strain signal by half-bridge and precise instrumentation amplifier, and employs an up-to-date RF system on chip to realize digitalization for analog voltage signal and wireless transmission. The wireless sensor nodes based on TI's Z-stack protocol possess high performances of network self-organization and network self-healing, and support low power consumption in wireless transmission by sleep mode.

Field-programmable gate array based arbitrary signal generator and oscilloscope for use in slow light and storage of light experiments

We present a field-programmable gate array (FPGA) based device that simultaneously generates two arbitrary analog voltage signals with the maximum sample rate of 1.25 MHz and acquires two analog voltage signals with the maximum sample rate of 2.5 MHz. All signals are synchronized with internal FPGA clock. The personal computer application developed for controlling and communicating with FPGA chip provides the shaping of the output signals by mathematical expressions and real-time monitoring of the input signals. The main advantages of FPGA based digital-to-analog and analog-to-digital cards are high speed, rapid reconfigurability, friendly user interface, and low cost. We use this module in slow light and storage of light experiments performed in Rb buffer gas cell.

SCM Based High Precision Temperature Controller Design

t is designed by adopting SUNPLUS SPCE061A version 16-bits Single Chip Microcomputer; it has realized functions as manual setting temperature, automatic temperature control, showing the real-time temperature of water. The testing mode of water temperature adopts AD590 version integrated analog temperature sensor to perceive the temperature of water in vessels and uses operational amplifier to amplify minute analog voltage signal outputted by sensor. It employs keyboard scan mode to set target temperature (40°C~90°C) and displays dynamically the real-time temperature of water with digestion. The system controls the guide circuit and closing of the heating device by using relay circuit, achieving the aim of keeping design temperature constant essentially. PID algorithm is adopted in water temperature control method. The proportion, integration and differential constant in PID algorithm are debugged with experiments in order to control the proportion of heating time and reduce the adjusting time of the system. The system boasts the advantages of high controlling precision, stability and reliability, flexible operation, strong currency.

Design of an Electronic Voltage Transformer Suitable for Digital Transformer Substation

In this paper an electronic voltage-current voltage transformer (EVCVT) scheme has been proposed based on voltage-current transformation, using the voltage - current transformation technology and weak current detection technology to achieve the accurate measurement of the grid voltage. It transforms the high voltage into low current by high voltage thick film resistor, then the current sensor transforms the low current signal into a standard analog voltage signal, thus an AD converter collects the voltage signal, and the value be imported into the microprocessor for filtration, calibration, coding. After filtering the data would be transmitted to the upper computer or relay protection devices of the digital substation. This paper focused on the design of hardware circuit of digital voltage transformer, developed the software package and produced a prototype control board. Initial experiments show that the scheme is valuable for digital substation.

Novel analog pulse‐width‐modulated 15‐μm SiGe micromirrors

Abstract— A novel six‐electrode SiGe micromirror pixel enabling analog pulse‐width modulation (PWM) in display applications is presented. Instead of utilizing bitplanes, arbitrary duty cycles can be realized, resulting in an analog gray‐level distribution. This eliminates the posterization (contouring) effect that is typical for digital micromirrors. Moreover, the pixel design does not require the incorporation of electronic comparators and the gamma compensation can be processed externally. Two out of the six electrodes are used as landing electrodes. The other four attracting electrodes are driven by two anti‐phase saw‐tooth signals and two fixed analog voltage signals. By applying this signal scheme, the duty cycle of the mirror is modulated in an analog manner. Test vehicles were manufactured where SiGe is the microelectromechanical systems (MEMS) material. The use of SiGe as a structural layer is advantageous to build MEMS since the CMOS and MEMS layers can be deposited in a monolithic manner. Measurements using a Laser Doppier Vibrometer (LDV) have confirmed the feasibility of analog PWM for 15‐μm SiGe micromirrors.

A digital technique for the on-line measurement of dissipation factor and capacitance

This paper reports a computer-aided system for on-line monitoring of dielectric dissipation factor tan /spl delta/, and capacitance of HV apparatus. The method employs the discrete Fourier transform (DFT) which is performed on the scaled down analog voltage and current signals obtained using a digital storage oscilloscope (DSO) board. The results are displayed using the graphic user interface implemented with graphic (G) language, This technique uses optimal values of measurement parameters as indicated by software simulation and laboratory tests. Field tests were conducted at Manitoba Hydro's Dorsey station to evaluate the insulation of a 230 kV current transformer unit using the developed system.

Enhanced Quantitative Analytical Capability with a Nuclear Magnetic Resonance (NMR) Spectrometer by Use of an External Integrating Recorder

Abstract A basic 60-MHz nuclear magnetic resonance (NMR) spectrometer (Varian EM360A) can be economically upgraded by external connection to an integrating chart recorder (Shimadzu C-R3A). The analog voltage signal corresponding to vertical pen position for signal peaks on the spectrometer's flatbed recorder can provide an input signal to the external recorder. Major benefits include improved objectivity in quantitation by digital electronic integration of peak areas, ability to reprocess spectra stored in memory, and improved tracing of fast signal peaks. Details of the interfacing procedure and a discussion of results are provided.

A novel wide dynamic range silicon photodetector and linear imaging array

A silicon photodetector structure utilizing the MOSFET subthreshold effect is discussed. This photodetector, which can be integrated on the same chip with MOSFET circuits or CCDs, provides an analog voltage signal over a wide dynamic range. Photodetector and arrays showed, in the visible spectrum an incoming radiation-detection light-intensity dynamic range of greater than 10/SUP 7/. In addition, the photodetector device was used to realize CCD and self-scanned MOSFET linear arrays. The theory of the new photodetector device and its use in forming linear imaging arrays are discussed. Experimental results are presented.

A novel wide dynamic range silicon photodetector and linear imaging array

A novel silicon solid-state photodetector structure utilizing the MOSFET subthreshold effect was conceived, developed, fabricated, and experimental results were obtained. This photodetector device, which can be integrated on the same chip with MOSFET circuits or CCD's, provides an analog voltage signal over a wide dynamic range. Fabricated photodetector devices and arrays showed experimentally, in the visible spectrum, an incoming radiation detection light intensity dynamic range of greater than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> . In addition, the novel photodetector device was used to realize CCD and self-scanned MOSFET linear arrays. In this paper, we describe in detail the theory of the new photodetector device and its applications to form linear imaging arrays. Finally, we present experimental results obtained on developed and fabricated devices and arrays.

A data converter for analog/fuzzy‐logic interface

AbstractInput signals are often fed as analog quantities into fuzzy logic processing systems. This paper proposes a method for configuring interface necessitated by fuzzy logic systems featuring analog inputs and digital processing. This interface is a data converter which processes input analog voltage signals and outputs digital signals suitable for fuzzy logic processing.The conversion principle is based on the concept of level sets within the fuzzyset theory, i.e., depending on whether a given analog signal belongs to level sets, the signal is quantized and converted to membership grade, simultaneously. Having programmable conversion characteristics, it can realize typical membership functions such as Z‐, ‐, and S‐functions.The operation of the converter, which is configured of counters, a memory, a digital‐to‐analog converter, and a comparator, is verified experimentally as regards a non‐monotonic and asymmetric membership function. the conversion accuracy is then discussed and the causes for error are described.

A NEW APPROACH TO TRANSIENT WAVE GENERATION

An analytical model of an "episodic" wave as a function of time is given. The linear dispersion theory is applied to the transient to hindcast the wave train at a wave board which is a specified distance up-wave from a test site. First order wave board theory and linear system theory is used to convert the wave train at the wave board into a control signal. Conversion of the time discrete control signal into a smooth analog voltage signal by means of a real time digital program is described. Examples of numerical simulations and physical measurements are given.