Conditioning Circuitry Research Articles

Control of a piezoelectrically actuated high-speed serial-kinematic AFM nanopositioner

Controller design to compensate vibration, hysteresis and time delay in a high-speed serial-kinematic X–Y nanopositioner is presented in this paper. A high-speed serial-kinematic X–Y nanopositioner, designed in-house, is installed in a commercial AFM and its scanning performance is studied. The impediments to fast scanning are (i) the presence of mechanical resonances in the nanopositioning stage, (ii) nonlinearities due to the piezoelectric actuators and (iii) time delay introduced by finite clock speeds of the signal conditioning circuitry associated with displacement sensors. In this paper an integral resonant controller is designed to mitigate the effect of the resonance along the X axis (fast axis). The control design accommodates for the time delay, thereby ensuring robust stability. A high gain integral controller is wrapped around the damped nanopositioner to ensure sufficient linearity near the region of operation. For actuation along the Y axis (slow axis), where the bandwidth requirement is less demanding, a notch filter is used to increase the gain margin and the nonlinearity is compensated using a high gain feedback controller. Enhancement in the scanning speed up to 200 Hz is observed. Imaging and tracking performance for open loop and closed loop scans up to 200 Hz line rate is compared and presented. Limitations and future work are discussed.

A New Scheme for Determination of Respiration Rate in Human Being using MEMS Based Capacitive Pressure Sensor: Simulation Study

Abstract In this paper, a MEMS based capacitive nasal sensor system for measuring Respiration Rate (RR) of human being is developed. At first two identical diaphragm based MEMS capacitive nasal sensors are designed and virtually fabricated. A proposed schematic of the system consists of signal conditioning circuitry alongwith the sensors is described here. In order to measure the respiration rate the sensors are mounted below Right Nostril (RN) and Left Nostril (LN), in such a way that the nasal airflow during inspiration and expiration impinge on the sensor diaphragms. Due to nasal airflow, the designed square diaphragm of the sensor is being deflected and thus induces a corresponding change in the original capacitance value. This change in capacitance value is to be detected by a correlated- double-sampling (CDS) capacitance-to-voltage converter is designed for a precision interface with a MEMS capacitive pressure sensor, followed by an amplifier and a differential cyclic ADC to digitize the pressure information. The designed MEMS based capacitive nasal sensors is capable of identifying normal RR (18.5±1.5 bpm) of human being. The design of sensors and its characteristics analysis are performed in a FEA/BEA based virtual simulation platform.

Physical insight into electromagnetic kinetic energy transducers and appropriate energy conditioning for enhanced micro energy harvesting

This paper proposes a new method for modeling electromagnetic kinetic energy transducers and gives analytical expressions that enable the design of efficient energy conditioning circuitry. The introduced transducer modeling approach achieves high accuracy without requiring a large set of parameters. The presented transducer characterization allows physical insight into fully assembled and packaged transducers in order to extract the required transducer model parameters without knowledge of the individual components. Moreover, the electromagnetic coupling, the parasitic damping, and the optimal load can be modeled with a dependence on the external excitation. Precise co-simulation with CMOS integrated energy conditioning circuitry is possible implementing this model in a circuit simulator.

Signal conditioning circuitry in ultrahigh-speed photoelectric raster interpolators

A circuitry of signal conditioners of ultrahigh-speed photoelectric raster interpolators used in absolute high-resolution optical encoders is described.

Improvement of the off-diagonal magnetoimpedance sensor white noise

This work deals with the analysis of noise sources of the off-diagonal magneto-impedance sensor with stress-annealed amorphous ribbon. This experimental analysis shows that the equivalent magnetic noise spectral density is mostly due to the electronic conditioning circuitry that operates the sensor. The electronic noise was then reduced with employment of an improved excitation-detection technique for our sensor and an equivalent magnetic noise spectral density below 1pT/Hz in white noise region has been reached. Indeed, the equivalent magnetic white noise level of the output signal decreased from 5pT/Hz to 560fT/Hz. Nevertheless, this noise level is still limited by the electronic conditioning, leaving room for further improvement.

A negative imaginary approach to the actuation of a guitar string

A feedback control approach to damp the resonances of a guitar string is considered. A guitar string is tightly stretched and fastened at both its ends. This string is placed in a magnetic field and set to vibrations by passing current through it. A displacement sensor is placed such that the actuator and the sensor are collocated. The linear dynamics characterizing the input/output (supplied current/measured displacement) relationship is identified and a model is fit. It is observed that the model satisfies the negative imaginary condition. An Integral Resonant Controller (IRC) is designed, by exploiting the negative imaginary characteristics, to damp the first five modes of the string. Signal conditioning circuitry associated with the sensor could introduce significant time delays that destroy the negative imaginary property. Here, an IRC is designed even when the system does not exhibit negative imaginary characteristics. The effectiveness these control designs are experimentally validated.

Energy Scavenging Device Based on Electric Field in Substations

Wireless sensor network has many advantages while energy supplying is a main limit. However, energy scavenging technology affords an efficient solution, especially in high voltage substations, there is swarmed with strong electromagnetic field, and the scavenging device based on electric field has an irreplaceable advantage. An equivalent mathematical model of the converter was established to study the energy harvesting effect. Another model of conditioning circuitry was further built to analyze the factors affecting charging current. Finally, several main factors and corresponding methods are analyzed to improve the energy scavenging efficiency.

Design Issues for a Portable Vocal Analyzer

The aim of this paper consists in identifying the main design specifications of a portable analyzer that allows the vocal signal of a person under monitoring to be acquired and stored. Suitable calibration procedures will be also defined for the microphone used in the portable device in order to ensure the traceability of the obtained measurements. The collected data will be used to identify voice disorders, to prevent an improper use of the voice, and to evaluate the vocal effort induced by noisy and/or reverberant environments. The vocal analyzer is based on a contact microphone worn by the person under monitoring and a portable microcontroller-based unit that hosts the conditioning circuitry, analog-to-digital converter, and storing memory. Two alternative sensors are investigated as contact microphones: an accelerometer and an electret condenser microphone. The former is expected to exhibit a negligible sensitivity to airborne effects, and the latter would provide a larger bandwidth, thus allowing parameters related to the vowel quality to be estimated. Particular attention will be paid toward traceability assurance and uncertainty estimation, and a calibration procedure for each of the estimated parameters will be proposed. In this paper, a data-acquisition-board-based setup has been used instead of a portable microcontroller unit in order to easily perform tests that allow the used microphones to be characterized and the calibration procedures for the parameters of interest to be assessed. Experimental results are reported that refer to the estimation of the parameters sound pressure level ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SPL</i> ) and fundamental frequency ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ).

Sensor less Wash Fluid Detection in Automotive Application

The proposed paper describes the hardware and software method used for detection of wash fluid level in water tank used in automotive; thereby eliminating the need for sensor (Reed type switch mounted on washer bottle) for low wash fluid detection. Wash motor is used for water spray on windscreen during wash and wipe operation. The proposed system makes use of hardware circuit used to drive the wash motor usually of DC (Direct current) type and a feedback circuitry to read back the current consumed by motor during particular wash operation. This hardware system is coupled with software algorithm such that during IGNITION ON instance wash motor will be turned on such as to get motor current readings to determine amount of load operated by motor which is related to wash fluid inside the washer bottle. Motor operation is optimized so as to avoid water spray causing nuisance to user. It also eliminates the cost of the sensor, wiring harness and related signal conditioning circuitry used for sensor data processing. The proposed invention does not suffer from mundane sensor faults such as short to battery / ground, sensor open wire output, variation due to vibration and wear/tear. Language: en

A Fully-Integrated, Miniaturized (0.125 mm²) 10.5 µW Wireless Neural Sensor

A wirelessly powered 0.125 mm2 65 nm CMOS IC for Brain-Machine Interface applications integrates four 1.5 μW amplifiers (6.5 μVrms input-referred noise with 10 kHz bandwidth) with power conditioning and communication circuitry. The multi-node backscatter frequency locks to a wireless interrogator using a frequency-domain multiple access communication scheme. The full system, verified with wirelessly powered in vivo recordings, consumes 10.5 μW and operates at 1 mm range in air with 50 mW transmit power.

MEMS-Integrated Load Cell for Measuring Pressure, Erosion, and Deposition in Dynamic Environmental Flows

A microelectromechanical system-based load cell is integrated with signal conditioning circuitry, temperature, and tilt sensors for measurement of sediment-fluid interaction and flow under turbulent conditions. Such an instrument has potential value for quantifying geophysical flows and sediment dynamics within a range of environments. Sensor sensitivity is tested to a mass of 0.5 g but can be shown theoretically to extend to 50 mg. The sensor is found to have no attenuation of frequencies up to 2.5 Hz and would therefore be suitable for monitoring turbulent flow. Laboratory flume experiments, simulating a dam burst, demonstrate the applicability of the sensor for measuring highly dynamic and transient flow phenomena in unprecedented detail.

Low-Power Circuits and Energy Harvesting for Structural Health Monitoring of Bridges

In this paper, we present a self-powered wireless sensor system for structural health monitoring of highway bridges. The system consists of an energy harvesting material, power conditioning circuitry, a sensor, an analog-to-digital converter, and a wireless transmitter. The energy harvesting material is a recently discovered NiMnCoIn magnetic shape memory alloy (MSMA), which converts mechanical vibrations first into a magnetization change and then, with assistance from a pick-up coil, into an alternating current (ac) output. The ac output of the MSMA is converted to a direct current (dc) voltage for powering a sensor and circuitry. Measurement results from a self-powered rectifier (SPR) and a six-bit successive approximation register analog-to-digital converter (SAR ADC) are presented, and implementation considerations are presented for the sensor and wireless transmitter. The SPR produces dc output voltages larger than 700 mV for loads larger than 100 kΩ with peak input amplitudes >;400 mVpk. A four-stage rectifier-multiplier is also implemented utilizing the proposed SPR as the first stage. The implemented SAR ADC is functional with a 0.9-V dc supply voltage (Vdd) and achieves an improved performance with a Vdd of 1.8 V, where the SAR ADC achieves a measured integral nonlinearity and differential nonlinearity of +1.2/-1.9 least significant bit and +1.3/-0.99 LSB, respectively. The SPR and SAR ADC are fabricated in a standard 0.5-μm CMOS process. The proposed sensor system can be fully optimized due to co-design capabilities. The lack of batteries makes this system ideal for deployment in bridge monitoring systems.

Noninvasive Temperature Measurement Based on Microwave Temperature Sensor

In this study, we have a research of the noninvasive temperature measurement based on microwave temperature sensor. Moreover, in order to solve the surface temperature measurement for designing microwave temperature sensor, the microwave was issued by the transmitting antenna. Microwave encountered by the measured object to return back to the measured object and then convert it into electrical signals, the use of the quantitative relationship between this signal and input noise temperature to real-time calibration. In order to calculate the antenna brightness temperature and then after signal conditioning circuit, which can show the temperature value, in order to achieve the detection of microwave temperature. Microwave-temperature measurement system hardware based on 89C51 microcontroller consists of the microwave temperature sensor, signal conditioning circuitry and chip control circuit, AD converter circuit and display circuit. The system software is by the main program, the AD conversion routines, subroutines and delay subprogram. The microwave temperature measurement characterize has: without gain fluctuations, without the impact of changes in the noise of the machine, to provide continuous calibration, wide dynamic range.

Analysis and Design of Conditioning Circuitry Used for Energy Scavenging Device

Energy scavenging device used for smart grid can achieve energy from electromagnetic field and convert it into electricity to power wireless sensors within substations. Due to the energy collected by the energy scavenging unit is unstable, a conditioning circuitry is essential. A conditioning circuitry is proposed, and modeling method is also established accordingly. Both large-signal model and dynamic disturbance model of the topology are presented as to analyze the static and dynamic characteristics. Remarkably, one duty cycle of the sensors is divided into the launch period and dormant period. At different period, their equivalent impedance is different, so the performance of conditioning circuit at different stages is analyzed. To realize it, a feedback control circuit should be considered in the design of the topology. Further, simulation based on PSIM is done to certify effectiveness of the proposed topology and optimized parameters.

Simulating Displacement and Velocity Signals by Piezoelectric Sensor in Vibration Control Applications

Intelligent structures with built-in piezoelectric sensor and actuator that can actively change their physical geometry and/or properties have been known preferable in vibration control. However, it is often arguable to determine if measurement of piezoelectric sensor is strain rate, displacement, or velocity signal. This paper presents a neural sensor design to simulate the sensor dynamics. An artificial neural network with error backpropagation algorithm is developed such that the embedded and attached piezoelectric sensor can faithfully measure the displacement and velocity without any signal conditioning circuitry. Experimental verification shows that the neural sensor is effective to vibration suppression of a smart structure by embedded sensor/actuator and a building structure by surface-attached piezoelectric sensor and active mass damper.

Embedded Module for 3-D Mechanical Strain Measurement

This paper presents the development and evaluation of a miniature (1 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) embedded electronic module that can resolve temperature-compensated mechanical strain in three dimensions. The module is designed to be embedded into materials and to measure, in-situ, all nine components of strain and to relay the information back to a PC via wired communications. The module can also be assembled as a component in a “parent” encapsulated electronic system and interface with the system's digital bus. The module comprises three miniature, off-the-shelf, three-gauge, rectangular rosettes that are assembled in a 3-D array so that all components of strain can be resolved. The module format is a cube, with the gauges on the outer faces of the cube, and the electronics on the inside. The electronics consists of signal conditioning circuitry, a 24-bit sigma-delta ADC, a microcontroller which sends the digital data directly to a master device such as PC, and an onboard temperature sensor for thermal compensation of the gauges. The module was evaluated by encapsulating it in epoxy and subjecting it to compressive and tensile testing in a mechanical tester. The results were compared to finite element simulations with an average of 7% difference between magnitudes and a standard deviation of 4%. Thermal evaluation of the module was also carried out by subjecting the test pieces to thermal loads and monitoring the response of the system. The module is believed to be the smallest yet reported self-contained, embedded system capable of resolving all components of 3-D strain, it is small enough to be embedded in a wide range of materials and structures without significant impact on the mechanical properties of its host. It can, therefore, be used in applications such as structural health monitoring and reliability prognostics and for calibration of mechanical/thermo-mechanical simulations.

POSFET touch sensor with CMOS integrated signal conditioning electronics

This paper presents the design, fabrication and evaluation of the new version of POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) touch sensing device based tactile sensing chip. Implemented using CMOS (Complementary Metal Oxide Semiconductor) technology, the chip consists of POSFET device and the integrated bias and signal conditioning circuitry. In particular, a high compliance current sink and an output buffer have been integrated to respectively bias the POSFET device and to decouple the sensor from chip output. The performance of tactile sensing chip has been evaluated in the dynamic contact forces range of 0.01–3N and the sensitivity of POSFET devices (without amplification) is 102.4mV/N.

Balloon-borne disposable radiometer for cloud detection

A low cost, disposable instrument for measuring solar radiation during meteorological balloon flights through cloud layers is described. Using a photodiode detector and low thermal drift signal conditioning circuitry, the device showed less than 1% drift for temperatures varied from +20 °C to -35 °C. The angular response to radiation, which declined less rapidly than the cosine of the angle between the incident radiation and normal incidence, is used for cloud detection exploiting the motion of the platform. Oriented upwards, the natural motion imposed by the balloon allows cloud and clear air to be distinguished by the absence of radiation variability within cloud, where the diffuse radiation present is isotropic. The optical method employed by the solar radiation instrument has also been demonstrated to provide higher resolution measurements of cloud boundaries than relative humidity measurements alone.

Powering a wireless sensor node with a vibration-driven piezoelectric energy harvester

This paper discusses the direct application of scavenged energy to power a wireless sensorplatform. A trapezoidal piezoelectric harvester was designed for a specific machine toolapplication and tested for robustness and longevity as well as performance. The designfocused on resonant performance and distributed strain concentrations at a given resonantfrequency and acceleration. Critical issues of power coupling and conditioning betweenharvester and wireless platform were addressed. The wireless platform consistedof a sensor, controller, power conditioning circuitry, and a custom low powerradio. The system transmitted a sensor sample once every 10 s in a scavengingenvironment of 0.25 g and 100 Hz for a system duty cycle of approximately 0.2%.

Impact of Electronic Conditioning on the Noise Performance of a Two-Port Network Giant MagnetoImpedance Magnetometer

The performance of giant magneto-impedance (GMI)-based magnetometers is currently limited by the noise due to the electronic conditioning circuitry. We propose a simple model of this noise for a GMI sensor using a synchronous detection scheme. The GMI sensing element consists of a thin pick-up coil wound around a Co-rich amorphous micro-wire. It is fully described by a two port network model and associated impedance matrix. Noise and sensitivity behavior are studied for the four measuring configurations, corresponding to four terms of the impedance matrix. The model yields a good description of experimental data from noise measurements. The magnetic noise spectral density is dominated either by the excitation or detection stages, depending upon whether the excitation currents are high or low. The nontrivial noise behavior exhibited by each configuration leads to better understanding of the noise limitations of GMI magnetometers. The configuration in which the signal at the coil terminals is measured (often called offdiagonal) is the most efficient in decreasing the equivalent output magnetic noise spectral density.