High-accuracy Measurement System Research Articles

Mathematical model of checkweigher with electromagnetic force balance system

Our aim was to develop a high-speed and high-accuracy mass measurement system to be used with a conveyor belt (a checkweigher). The objective in this paper was to present a dynamic model of our proposed measurement system. The checkweigher with an electromagnetic force balance system was approximated using a spring-mass-damper system as the physical model, and the equation of motion was derived. The model parameters could be obtained from experimental data. Finally, the validity of the proposed model was confirmed by comparison of the simulation results with the experimental responses. The dynamic model obtained offers practical and useful information to examine the control scheme and to achieve high-performance mass measurement.

Design and Evaluation of a High-Accuracy Measurement System for Sheet Resistance of Thin Films

Inspection and measurement for the sheet resistance and resistivity play a pivotal role in the semiconductor industry. In this study, a high-accuracy measurement system for sheet resistance of thin films was designed based on dual-measurement with four-point probe method. The measurement system was composed of a special switching circuit, a digital output module, Keithley 2400 SourceMeter, and a computer running LabVIEW. The special switching circuit designed based on the multiplexer played an important role in current probes and voltage probes automatic switching under the control of virtual instrumentation software LabVIEW and National instruments digital output module hardware NI 9401. Keithley 2400 SourceMeter controlled by LabVIEW was used for two-times high-precision voltage measurement. Van der Pauw correction factor were calculated based on the results of the two-times voltage measurement. Then the sheet resistance of thin films was calculated by LabVIEW softwares powerful computing. The experimental results show that the designed and developed system can meet the needs of fast on-line measurement of thin films sheet resistance with a wide range, and moreover, the accuracy of measurements and the level of automatization have been dramatically improved compared to the conventional measurement system.

Research of Super-Size Intelligence Flow Measurement System

In this paper, we study a kind of intelligent and high-accuracy flow measurement system, which is a type of venturi tube flowmeter that surpassed the international standard ISO5167. This paper analyzes the characteristics of the super-size flow measurement in the water transportation and industrial projects, and the choice for suitable flow meters. We study the practical compensation technology for discharging coefficient “C” of the international-standard-exceeding venturi tube, and puts forward water calibration method for venturi tube, and design the intelligent and high-accuracy flow metering system based on computer technology. Furthermore, this paper analyzes the calibration data of water flow, and propose the segment and compensation method for discharging coefficient “C” practically. We solved the limitations of the international-standard-exceeding venturi tubes, and effectively improved the accuracy and range of the flow measurement system.

ECT Evaluation by an Error Measurement System According to IEC 60044-8 and 61850-9-2

A high-accuracy error measurement system for calibration of digital-output equipped electronic current transformers (ECTs) is described. The system has been developed in conformity with the requirements for digital information networks in IEC 61850-9-2 and for accuracy class and error measurement procedures in IEC 60044-8. The system has also been designed to achieve simultaneous and synchronous samplings between an ECT/MU and a reference measuring unit, a procedure for capturing and filtering sampled value (SV) packets and data processing using the discrete Fourier transform with error compensations for an integrating analog-to-digital converter. The system employs a prototype commercial digital-output equipped ECT consisting of an optical current transformer (OCT) and a merging unit (MU). The error sources of the system are discussed for the error compensations and uncertainty estimations. Based on the principle of the system, the accuracy and temperature dependence of the prototype OCT/MU are evaluated and are confirmed to be within the limits of errors of accuracy class 0.2S.

A high-accuracy and convenient figure measurement system for large convex lens

We present a novel optical configuration of a phase-shifting interferometer for high-accuracy figure metrology of large dioptric convex spherical surfaces. The conformation and design considerations according to measurement accuracy, practicability, and system errors analysis are described. More in detail, we show the design principle and methods for the crucial parts. Some are expounded upon with examples for thorough understanding. The measurement procedures and the alignment approaches are also described. Finally, a verification experiment is further presented to verify our theoretical design. This system gives full-aperture and high-precision surface testing while maintaining relatively low cost and convenient operation.

A Study on Position Measurement System Using Laser Range Finder and its Application for Construction Work

This paper describes a study of high accuracy and low cost position measurement system using Laser Range Finder (LRF), and its application for construction pile work. Since the LRF is a sensor which can measure distance to surfaces of objects by radiating laser beams from itself and receiving the reflected ones, an obtained data from the LRF are nothing more than the contours of objects. In proposed system, the obtained data from LRF assumed the arc-shaped contours of the bar, the center position was analyzed introducing the least square method and maximum likelihood estimation. The error between the analysis and the measurement corresponds enough to the allowable accurate range. Additionally, improving the angular resolution of the LRF by using a pan unit, the highest accurate center position was able to be acquired. Applying this system to the construction work, the high accurate pile marking and the pile drive positioning were recognized. Since this measurement was achieved by only a worker and the position and direction of the worker was easily found, the high efficient and short term works were surely performed.

High-accuracy photoreceiver frequency response measurements at 155 µm by use of a heterodyne phase-locked loop

We demonstrate a high-accuracy heterodyne measurement system for characterizing the magnitude of the frequency response of high-speed 1.55 µm photoreceivers from 2 MHz to greater than 50 GHz. At measurement frequencies below 2 GHz, we employ a phase-locked loop with a double-heterodyne detection scheme, which enables precise tuning of the heterodyne beat frequency with an RF synthesizer. At frequencies above 2 GHz the system is operated in free-run mode with thermal tuning of the laser beat frequency. We estimate the measurement uncertainties for the low frequency range and compare the measured high-frequency response of a photoreceiver to a measurement using electro-optic sampling.

A Low-cost Ultrasonic 3D Measurement Device for Calibration for Cartesian and Non-Cartesian Machines

The major obstacles to the widespread adoption of 3D measurement systems are accuracy, speed of process and the cost. At present, high accuracy for measuring 3D position has been achieved, and there have been real advances in reducing measurement time, but the cost of such systems remains high. A high-accuracy and high-resolution ultrasonic distance measurement system has been achieved in this project by creating multi-frequency continuous wave frequency modulation (MFCWFM) system. The low-cost system measures dynamic distance (displacements of an ultrasound transmitter) and fixed distance (distances between receivers). The instantaneous distance between the transmitter and each receiver can be precisely determined. New geometric algorithms for transmitter 3D position and receiver positing have also been developed in the current research to improve the measurement system‟s practicability. These algorithms allow the ultrasound receivers to be arbitrarily placed and located by self-calibration following a simple procedure. After the development and testing of the new 3D measurement system, further studies have also been carried out on the system, considering the two major external disturbances: air temperature drifting and ultrasound echo interference. Novel methods have been successfully developed and tested to minimize measurement errors and evaluation of speed of sound. All the enabling research described in the thesis means that it is now possible to build and implement a measurement system at reasonable cost for industrial exploitation. This will have the necessary performance to provide ultrasonic 3D position measurements in real time for monitoring position.

1A1-A18 植物群落精密計測プラットフォームの開発 : GPSとセンサーの高精度同期手法

High-accuracy 3-dimensional measurement system was developed to acquire the Information of topography and plant status in the farm land. Laser scanners and a hyperspectral camera were used as sensors. The method which synchronizes between a GPS time and sensors were developed using low-cost synchronization circuit board. As a result, 1pps signal and 75Hz signal provided for laser scanners were synchronized with accuracy of 0.2μs and the laser scanner and 75Hz signal were synchronized with accuracy of 0.12ms.

An Evaluation of Calibration Techniques for In Situ Carbon Dioxide Measurements Using a Programmable Portable Trace-Gas Measuring System

Abstract The construction and deployment of a portable trace-gas measurement system (TGaMS) is described. The air-collection system (dubbed HYDRA) collects air samples from 18 different locations and was connected to either one or two LI-COR LI-7000 gas analyzers to measure CO2. An in situ “field calibration” method, that uses four calibration gases with an uncertainty on the order of ±0.1 μmol mol−1 relative to the WMO CO2 mole fraction scale, revealed CO2 output from the LI-7000 had a slightly nonlinear relationship relative to the CO2 concentration of the calibration gases. The sensitivity of the field-calibrated CO2 to different forms of the field-calibration equation is investigated. To evaluate TGaMS performance, CO2 from collocated inlets, portable gas cylinders, and nearby independent CO2 instruments are compared. Results are as follows: 1) CO2 measurements from HYDRA multiple inlets are feasible with a reproducibility of ±0.4 μmol mol−1 (based on the standard deviation of the CO2 difference between collocated inlets when HYDRA was operating with two LI-7000s); 2) CO2 differences among the various field-calibration equations were on the order of ±0.3 μmol mol−1; and 3) comparison of midday hourly CO2 measurements at 30 m AGL between TGaMS and an independent high-accuracy CO2 measurement system (within 300 m of TGaMS) had a median difference and standard deviation of 0.04 ± 0.81 μmol mol−1 over two months.

A technique for high-accuracy flux measurement using a relaxed eddy accumulation system with an appropriate averaging strategy

Continuous observation of carbon dioxide (CO2) flux is an important issue to understand the global carbon cycle. Although the eddy covariance (EC) method is a promising means of measuring the fluxes, its high cost is often constraint. We therefore developed a technique for a high accuracy measurement system using a relaxed eddy accumulation (REA) method with an inexpensive gas analyzer, and tested the measurement system compared with the EC measurement at a cypress forest. Since spectral analysis revealed that the gas analyzer had both high and low frequency noise, we eliminated the former by using a moving average, and then calculated mean concentration with a shorter averaging period to avoid the low frequency noise, whereby the accuracy of the gas analyzer was improved at least 10-fold beyond the specification. The measured diurnal variation and the magnitude of CO2 fluxes by the EC and REA methods were almost identical, suggesting that our REA system was highly accurate as well as the EC system. The estimated root mean square error (RMSE) of the CO2 flux between the EC and the REA methods was 0.17 mg CO2 m-2 s-1. Although the open-path EC method could not be used to measure the flux during the rain event, spectral analysis suggested that the measured flux by the REA method was reliable during rainfall. The proposed measurement system will be applicable to the backup of the EC measurement as well as other trace gas flux measurements.

Voltage-Modulated Flow Rate for Precise Thrust Control in Colloid Electrospray Propulsion

We describe a feature of electrospray operation that allows precise control of flow rate through an electrospray emitter by use of the extraction voltage. The effect of extractor voltage on the propellant flow rate through an electrospray emitter has been determined for triethylene glycol and ethylene glycol solutions doped with varying levels of sodium iodide and the ionic liquid 1-ethyl-3-methyl imidazolium tetrafluoroborate using an in-line high-accuracy flow measurement system. In these experiments, a nominally fixed flow rate, obtained by providing a fixed supply pressure, is observed to be influenced by the applied voltage during stable cone-jet electrospray production. The relative sensitivity of flow rate to applied voltage was found to be higher as the nominal flow rate decreased. This method of flow rate control holds particular significance for colloidal electrospray thruster systems, which operate at or near minimum flow rate conditions.

Development of a High-Speed and High-Accuracy Measurement System for Micro Edge Radius of Long Precision Tool

This paper describes a measurement system for the edge radius of a long precision tool. A line-CCD camera is employed to scan the tool edge over the entire tool length. The edge width of the tool at each scanning point is first evaluated from the image of the line-CCD camera. The edge radius is then calculated from the edge width based on the calibration results using pin gauges. A multi-line scanning method is proposed to reduce the defocus errors caused by the out-of-straightness error of the scanning stage. Experimental results have shown that the edge radii over the entire length of a 5100 mm long tool can be evaluated in 30 minutes.

High Accuracy Measurement System of Surface Shape Using Grating Projection Method with Image Composition

High Accuracy Measurement System of Surface Shape Using Grating Projection Method with Image Composition

High-accuracy absolute measurement of the refractive index of air

A high-accuracy absolute measurement system of the refractive index of air is proposed. The measurement of the instantaneous index of refraction is achieved by comparing two laser optical paths with a differential laser interferometer. The vacuum optical path length is varied via a motor-driven trapezoidal vacuum cavity moving through a known distance. Compared to other measurement methods, the sealed vacuum cavity requires no vacuum pumping between measurements, and allows this method to function well in industrial applications. The measurement accuracy is better than 5×10–8.

Observation and analysis of large-scale human motion

Many team sports include complex human movement, which can be observed at different levels of detail. Some aspects of the athlete's motion can be studied in detail using commercially available high-speed, high-accuracy biomechanical measurement systems. However, due to their limitations, these devices are not appropriate for studying large-scale motion during a game (for example, the motion of a player running across the entire playing field). We describe an alternative approach to studying such large-scale motion, and present a video-based, computer-aided system, developed specifically for the purpose of acquiring large-scale motion data. The baseline of our approach consists of sacrificing much of the spatial accuracy and temporal resolution of widely used biomechanical measurement systems, to obtain data on human movement that span large areas and long intervals of time. Data can be obtained for each of the observed athletes with reasonable amount of operator work. The system was developed using the recordings of a handball match. Several field tests were performed to assess measurement error, including comparison to one of the widely available biomechanical measurement systems. With the help of the system presented, we could obtain position data for all 14 handball players on a 40×20 m large court with RMS error better than 0.6 m, covering 1 h of action. Several results, obtained during the handball match study are presented, in order to highlight the importance of large-scale motion acquisition.

Electronic devices for controlling high-accuracy IR measurement systems

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text A. G. Bugaenko and R. I. Zaripov, "Electronic devices for controlling high-accuracy IR measurement systems," J. Opt. Technol. 69, 241- (2002) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

High-accuracy wavelength-change measurement system based on a Wollaston interferometer, incorporating a self-referencing scheme

A novel wavelength-difference measurement scheme with a Wollaston prism is presented. By using a suitable reference wavelength, a small variation in the signal wavelength can be converted into a relatively larger change in the modulated wavelength, as a result of the so-called fringe beating effect, resulting in enhanced measurement sensitivity by use of autocorrelation and Gaussian filtering techniques. From the results of a simulation carried out, we observed a wavelength variation of 0.01 nm over 15 nm or 0.1 nm over 60 nm for a typical pair of laser diodes with wavelengths of 785 and 810 nm, and wavelength variations of 0.5 nm over 40 nm or 1 nm over 110 nm for 671-and 785-nm wavelengths. These results were partially verified by the experimental results obtained for which a resolution of 0.01 nm over a range of 2.5 nm for the first pair and 0.5 nm over 4 nm for the second pair of laser diodes was seen. The results have applications to the determination of wavelength variations in a wavelength-division multiplexing system or measurement of the wavelength changes induced in a range of optical sensors.

LASERTRACE

AbstractLasertrace is a high accuracy measurement system for the remote, non‐contact determination of position, velocity, or acceleration in two or three dimensions. It uses advanced two axis laser steering technology to locate and measure the angular position, from itself, of an identified point on an object under investigation. If the object subsequently moves, the steerable laser beam actually tracks the point providing updated position coordinates as it does so. An operating window of 40° in both axes guarantees system versatility in a wide range of applications.

Automated High-Accuracy Phase Measurement System

Automated High-Accuracy Phase Measurement System