Precise Measurement System Research Articles

A precise position measurement system of roll-to-roll printing using burst alignment patterns

Printed electronics involve a process of creating electrical devices by printing with conductive ink on flexible substrates. This process is environmentally-friendly and affordable, and thus suited for mass production. Roll-to-roll printing is a common method classified under printed electronics. This method uses a roll to apply pressure to film or metallic foil, and prints with conductive ink. To commercialize printed electronic technology using roll-to-roll printing, it is necessary to improve the superposition accuracy. Superposition accuracy refers to the position error between the layers. If the superposition accuracy is poor, the product quality drops due to electrical interference resulting from misalignment. To enhance the superposition accuracy of printed electronics, precise measurements of the web position must initially be obtained. In a previous study, this issue was resolved through the development of a position measurement system for precision alignment. This study improves the web position measurement system of the preceding study by applying a burst alignment pattern. The burst alignment pattern expands the linear measurement range of the optical encoder, and the directions of errors can be determined through signal analysis.

The Self-Calibration Method for the Vertex Distance of the Elliptical Paraboloid Array

The elliptical paraboloid array plays an important role in precision measurement, astronomical telescopes, and communication systems. The calibration of the vertex distance of elliptical paraboloids is of great significance to precise 2D displacement measurement. However, there are some difficulties in determining the vertex position with contact measurement. In this study, an elliptical paraboloid array and an optical slope sensor for displacement measurement were designed and analyzed. Meanwhile, considering the geometrical relationship and relative angle between elliptical paraboloids, a non-contact self-calibration method for the vertex distance of the elliptical paraboloid array was proposed. The proposed self-calibration method was verified by a series of experiments with a high repeatability, within 3 μ m in the X direction and within 1 μ m in the Y direction. Through calibration, the displacement measurement system error was reduced from 100 μ m to 3 μ m . The self-calibration method of the elliptical paraboloid array has great potential in the displacement measurement field, with a simple principle and high precision.

Precise monocular vision-based pose measurement system for lunar surface sampling manipulator

Space manipulator has been playing an increasingly important role in space exploration due to its flexibility and versatility. This paper is to design a vision-based pose measurement system for a four-degree-of-freedom (4-DOF) lunar surface sampling manipulator relying on a monitoring camera and several fiducial markers. The system first employs double plateaus histogram equalization for the markers to improve the robustness to varying noise and illumination. The markers are then accurately extracted in sub-pixel based on template matching and curved surface fitting. Finally, given the camera parameters and 3D reference points, the pose of the manipulator end-effector is solved from the 3D-to-2D point correspondences by combining a plane-based pose estimation method with rigid-body transformation. Experiment results show that the system achieves high-precision positioning and orientation performance. The measurement error is within 3 mm in position, and 0.2° in orientation, meeting the requirements for space manipulator operations.

Design & implementation of a high precision & high dynamic range power consumption measurement system for smart energy IoT applications

Internet of Things (IoT) devices have strict necessity for power consumption in order to achieve expected battery life. IoT nodes feature extreme power consumption range over 100 dB, between their operating modes. The main focus of this paper is to design and implement a high precision, high dynamic range, low power, and flexible power measurement system, which can be applied to different applications. The proposed system consists of a voltage regulating control loop, zero offset amplifiers, high precision analog to digital converters, and reference voltage. The proper operation of the proposed circuit are verified numerically with simulations and experimental measurements. The implemented system features maximum sampling rate of 5 MHz, load regulation error of 0.16%, and linearity error of 0.32%. It is expected that the proposed system provides clear information of power behavior of IoT devices, which can be used for network’s power optimization as well as a self-power test equipment.

Errors of Multiplying D/A Converters Used for Precise AC Voltage Division

High-resolution multiplying digital-to-analog converters (MDACs) are often used as digitally controlled ac voltage dividers in precise instruments and measurement systems. Proper application of these converters requires knowledge of their parameters, especially amplitude and phase errors, which are usually not specified by MDAC manufacturers. This paper presents the results of investigations of voltage amplitude ratio errors and phase errors, as well as the time stability of voltage ratio and phase shift of selected commercial 16- and 18-bit MDACs. These parameters were measured with a dedicated high-resolution sampling system. The amplitude ratio and phase errors were determined as a function of the MDAC digital input word. Phase errors were also determined as a function of frequency.

Fiber Brag grating monitoring of a morphing wing based on a polyvinyl chloride reinforced silicone substrate

Abstract Here, the three-dimensional (3D) shape monitoring of polyvinyl chloride (PVC)-reinforced silicone substrate for a morphing wing is detailed, using Fiber Bragg grating (FBG) sensors. An optical fiber FBG sensor was embedded into a soft silicone substrate, which was glued onto the surface of a PVC substrate. This substrate was aligned with the morphing wing’s flexible ribs of the. Sensing experiments were carried out both with and without the PVC reinforced silicone substrate, and the sensitivity and repeatability of the two sensors were compared. The PVC-reinforced silicone substrate sensor was calibrated using standard curvature calibration blocks to obtain a relationship between wavelength shift and the bending curvature of the PVC-reinforced silicone substrate, and the wing shape was reconstructed at different deformation states. Several wing shapes were also reconstructed using a precise visual measurement system. Comparing the FBG sensing method with this visual measurement system demonstrated the effectiveness of the FBG method proposed here. Its maximum error was

Infrared Thermopile Temperature Measurement Technique in Microwave Heating Systems

Temperature measurement in microwave systems is essential for thermally driven processes, namely, catalytic reactions and ceramic sintering. Although, the application of direct thermometry methods, namely, thermocouples, have been commonly articulated in the available literature, however, contacted temperature measurement mechanisms have aroused concerns associated with the disruption of the electromagnetic field and local distortion of the field pattern leading to unprecedented measurement uncertainties. Consequently, the application of optical measurement methods has been advocated to diminish the associated concerns. However, due to the economical constrains and measurement range restrictions, the application of optical measurement systems, namely, pyrometers and optical fibers, has been deferred. In this study, an infrared thermopile, a precise and feasible temperature measurement system has been developed and calibrated to perform in microwave irradiation. Furthermore, the accuracy of the developed temperature system has been compared with the thermometry technique. It was concluded that thermopile stipulates unrivalled precision, succeeding a profound calibration procedure. It was further demonstrated that the thermopile is capable of the temperature measurement of the dielectric surfaces, exclusively, while the grounded thermocouple monitored the bulk temperature, a proportion of the gas phase and the solid phase temperature values. Consequently, the application of a thermopile coupled with a thermometry measurement method has been proposed to monitor the temperature of the dielectric catalyst active sites in gas-solid catalytic microwave-heated reactions.

Design of a Measurement System for Simultaneously Measuring Six-Degree-Of-Freedom Geometric Errors of a Long Linear Stage.

This study designs and characterizes a novel precise measurement system for simultaneously measuring six-degree-of-freedom geometric motion errors of a long linear stage of a machine tool. The proposed measurement system is based on a method combined with the geometrical optics method and laser interferometer method. In contrast to conventional laser interferometers using only the interferometer method, the proposed measurement system can simultaneously measure six-degree-of-freedom geometric motion errors of a long linear stage with lower cost and faster operational time. The proposed measurement system is characterized numerically using commercial software ZEMAX and mathematical modeling established by using a skew-ray tracing method, a homogeneous transformation matrix, and a first-order Taylor series expansion. The proposed measurement system is then verified experimentally using a laboratory-built prototype. The experimental results show that, compared to conventional laser interferometers, the proposed measurement system better achieves the ability to simultaneously measure six-degree-of-freedom geometric errors of a long linear stage (a traveling range of 250 mm).

Optical based Precision Measurement System and Its Application on Dynamic Force Measurement

Force is one of the basic quantities of mechanics, which is usually measured using a force transducer. However, the force transducer is usually calibrated by a static method. While the dynamic calibration for the force transducer is not sufficient. Dynamic calibration and measurement are needed to measure and evaluate mechanical parameters of materials in industry and research applications such as material testing, measurement of friction of a material, motion control, and crash testing. Dynamic measurement of force is also very necessary to produce and evaluate force with micro-Newton levels. However, there are difficulties in dynamic measurement, namely: there are difficulties in evaluating the inaccuracies in the measurement of varying forces, then there is difficulty in evaluating the inaccuracy in the time when measuring force. To overcome this problem, an optical-based precision measurement system was developed. This system can measure the force with high accuracy without using a force transducer. In the developed system, a levitated load (moving part) is used as a reference force imposed on the material to be measured for mechanical parameters. The inertial force of the levitated load is calculated accurately as a result of the multiplication between the load mass and its acceleration. In systems that are developed, speed, acceleration, force, and position are calculated accurately from the shift in the laser beam Doppler frequency reflected by the load. So that the measurement accuracy is strongly influenced by the accuracy of frequency calculations. In this system, a special program for zero-crossing-based frequency estimation is also very accurate. The developed system has proven to be able to perform mechanical/dynamic measurements and can evaluate the style with newton-level micro very accurately.

Precise Cobb Angle Measurement System Based on Spinal Images Merging Function

BackgroundConvenient and precise measurement of the Cobb angle using a small size X-ray detector has been required for local clinics. MethodsCobb angle measurement system using a conventional X-ray source and detector is proposed for accurate Cobb angle measurement. The system consists of a conventional X-ray source, a ruler-added X-ray table, a conventional X-ray detector, and an image processing program. The X-ray table has the lead ruler patterns. The patterns remain white ruler patterns on X-ray images. The proposed image processing program merges the three spinal X-ray images into one whole spinal X-ray image by detecting the ruler patterns on the three spinal X-ray images. ResultsIn order to evaluate our program, Cobb angle measured in the merged image is compared with Cobb angle measured in the X-ray image taken by a large X-ray detector. Average of difference between them is 2.251 degree and standard deviation is 1.339. ConclusionThe developed measurement system demonstrated its measurement performance accurately and practically.

A Novel Approach to Investigating Transport of Lost Circulation Materials in Rough Fracture

The drilling fluid loss or lost circulation via fractures is one of the critical engineering problems in the development of deep oil and gas resources. The conventional treatment is to introduce granular lost circulation material (LCM) into the drilling fluid system to plug fractures. In this work, a method incorporating the fracture surface scanning technique and coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) numerical simulation is proposed for the first time to investigate how the LCM particles plug rough fractures. The rough fracture model is built utilizing a high resolution and high precision measurement system. The LCM particle transport and plugging process in rough fractures are captured in the CFD-DEM numerical simulations. The results show that the local fracture aperture has a significant influence on LCM particle transport and the distribution of the plugging zone. The drilling fluid loss rate will decrease, and the drilling fluid pressure will redistribute during the accumulation of LCM particles in the fracture. The fracture plugging efficiency of nonspherical LCM is improved as a result of formation of multi-particle bridges. This study provides a novel approach and important theoretical guidance to the investigation of LCM particle transport in rough fractures.

Fast and precise 6D pose estimation of textureless objects using the point cloud and gray image.

Pose estimation for textureless objects is a challenging task in robotics, due to the scanty information of surfaces. In this paper, we design a vision system for fast and precise position and orientation measurement of textureless objects with a depth camera and a CCD camera. The corresponding process includes two parts: object segmentation in the point cloud and pose measurement in the gray image. Considering the relation between the object and its fixed panel, we first extract the panel in the point cloud by combining a random sample consensus algorithm with local surface normal. We then coarsely segment the possible area of the object based on an oriented bounding box. Finally, we transform the point cloud coordinates into the image coordinate system, and measure the precise pose of the object with a view-based matching method. Two types of cameras are brought together to make their respective advantages play well. The downscale method and coarse-to-fine strategy are utilized sufficiently to increase efficiency. Experiments show that our vision system achieves high pose measurement precision and enough efficiency. The average error is less than 2 mm for x and y, less than 4 mm for z, and 1° in orientation, meeting the requirements for our robotic grasping task.

Advances in Sea Surface Layer Temperature Measurements with Fast Responding Thermistor Arrays on Drifting Buoys

A precise and accurate ocean temperature measurement system is essential for better understanding and knowledge of the spatial and temporal variability of thermal stratification of the upper-ocean layers is fundamental. The National Institute of Ocean Technology, Chennai has indigenously developed a novel negative temperature coefficient (NTC) thermistor based sensor array with RS232 digital output for drifting buoy (Pradyu) (DB) wherein, it is mainly used in ocean observation applications. The DB is built with Indian satellite (INSAT) for real time data telemetry. The NTC sensing element is used in developing the temperature sensor for the measurement of sea surface layer temperature. The Steinhart–Hart equation and coefficients are applied on each sampling to zero down the error components involved in temperature measurements which corresponds to the nonlinear functionality of the NTC element. In-house developed SST sensor and sensor array are calibrated and extensively tested in laboratory conditions. The results of the SST and sensor array laboratory calibrations and field validations are briefly presented here with significant data sets collected in the Bay of Bengal warm pool regions.

The EORTC CAT Core—The computer adaptive version of the EORTC QLQ-C30 questionnaire

BackgroundTo optimise measurement precision, relevance to patients and flexibility, patient-reported outcome measures (PROMs) should ideally be adapted to the individual patient/study while retaining direct comparability of scores across patients/studies. This is achievable using item banks and computerised adaptive tests (CATs). The European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ-C30) is one of the most widely used PROMs in cancer research and clinical practice. Here we provide an overview of the research program to develop CAT versions of the QLQ-C30's 14 functional and symptom domains. MethodsThe EORTC Quality of Life Group's strategy for developing CAT item banks consists of: literature search to identify potential candidate items; formulation of new items compatible with the QLQ-C30 item style; expert evaluations and patient interviews; field-testing and psychometric analyses, including factor analysis, item response theory calibration and simulation of measurement properties. In addition, software for setting up, running and scoring CAT has been developed. ResultsAcross eight rounds of data collections, 9782 patients were recruited from 12 countries for the field-testing. The four phases of development resulted in a total of 260 unique items across the 14 domains. Each item bank consists of 7–34 items. Psychometric evaluations indicated higher measurement precision and increased statistical power of the CAT measures compared to the QLQ-C30 scales. Using CAT, sample size requirements may be reduced by approximately 20–35% on average without loss of power. ConclusionsThe EORTC CAT Core represents a more precise, powerful and flexible measurement system than the QLQ-C30. It is currently being validated in a large independent, international sample of cancer patients.

Design of the Integral Field Measurement System of Dipole Magnets

A new proton therapy facility (HUST-PTF) is under construction in the Huazhong University of Science and Technology. The integral field measurement system of dipole magnets was designed for the beamline of HUST-PTF. The design goal is to build a reliable, precise, and automatic measurement system, which is accurate enough to characterize the magnetic field quality of the dipole magnets. The system consists of long coils, precision motion stages, data acquisition, and control system. The design of the whole system and the measurement method is described in this paper. The design and fabrication of the long coil are also discussed, and the errors from the geometric frame of coil and electronic equipment are analyzed.

Highly precise and real-time measurements of 13CO2/12CO2 isotopic ratio in breath using a 2 μm diode laser

Real-time breath gas analysis with high accuracy, precision and time resolution, as a promising, non-invasive, fast and reliable tool, is important in medical diagnostics. Especially stable isotopologues of carbon dioxide is applied to multiple research areas including the diagnosis of gastrointestinal diseases. Helicobacter pylori (H. pylori) is one of the most frequent bacterial infectious diseases in human beings and is now recognized as one of the key risk factors for chronic gastritis, peptic ulcers, stomach cancer and lymphoma. In contrast to traditional invasive tests, the most reliable non-invasive method in the diagnosis of the H. pylori infection is considered to be 13C-urea breath test which is implemented by measuring the 13CO2/12CO2 isotope ratio in human breath. Tunable diode laser absorption spectroscopy (TDLAS) has the advantages of fast response, low drift, good gas selectivity and high detection sensitivity, and it is very convenient to develop a high precision, real-time and online measurement system. A precision laser spectrometer for the measurement of CO2 isotope abundance in human breath (with CO2 concentration of 4%-5%) or high concentration gas is designed and evaluated based on TDLAS technology. The spectrometer contains a novel compact dense-pattern multipass cell with a small volume of 280 cm3 and an effective optical path length of 26. 4 m. The cell is in conjunction with a fiber-coupled distributed feedback diode laser operating at 2.008 μm. Wavelength modulation spectroscopy approach is used. The mass flow, pressure and temperature of the cell are actively controlled, and able to keep long-term stability. The influence of laser power fluctuation is eliminated by fitting the baseline with cubic polynomial to normalize the raw spectrum. Moving window regression is used to remove the influence of frequency drift on measuring isotope abundance. The system measurement precision is improved by wavelet denosing and Kalman filtering. The experimental results demonstrate that moving window regression method not only extends the stability time of the system but also improves the measurement precision of isotope abundance well, the wavelet denoising improves the signal-to-noise ratio by 2 times that by the method of multi-spectral average, the stability time of the system is 100 s given by Allan variance, and the measurement precision of CO2 isotope ratio is 0. 067‰ after Kalman filtering. The use of small multi-pass cell and the default of denoising devices make the system more portable and improve the real-time and online measurement performance of the system. In addition to the measurement of 13CO2/12CO2 isotope ratio in human breath, by replacing different lasers, the spectrometer can also be used to measure trace gas concentration and the stable isotope abundance of many gas molecules in atmosphere. Therefore, the spectrometer will have broad applications in the areas of medical diagnosis, carbon cycle study and environmental monitoring.

On-machine multi-directional laser displacement sensor using scanning exposure method for high-precision measurement of metal-works

We propose a multi-directional triangulation optical system and scanning exposure method for precise height displacement measurement of metal-works. It is difficult to measure metal surfaces precisely with a conventional triangulation-laser displacement sensor due to machining traces. Because reflection characteristics vary by position on the workpiece, measurement errors occur even with positions of the same height. Our multi-directional triangulation optical system performs triangulation using a lens array consisting of four lenses located in a cross. Since our optical system can detect reflected light from four directions, we can achieve high-precision measurement even if the reflection characteristics vary. In addition, our scanning exposure method accumulates reflected light from many positions by scanning a projection beam onto a workpiece during the image sensor’s exposure time. Because the shape of a spot image on an image sensor is the sum of the reflected light from many positions, measurement error due to measurement position is reduced. Our proposed methods can achieve on-machine deflection measurement of metal-works with a target accuracy of ±1μm.

Dynamic research of multi-body mechanical systems of angle measurement

Analysis of the influence of vibrations on the calibration uncertainty of an angle limb is crucial for achieving high calibration accuracy. In modern equipment, the calibration is implemented in dynamic mode when the position of the raster elements is detected in the motion of the comparator’s movable components. The research object of this work is a newly designed angle measurement comparator that operates in dynamic mode. The main aim of this research is to determine the dynamic effects influence to the accuracy of the angle comparator. During the modelling of calibration errors related to dynamic influences, it is necessary to evaluate elastic deformations related to the vibrations excited by internal and external sources. Dangerous resonance frequencies and the character of the elastic deformations of the precise angle comparator carriage, which increase the angle calibration error, were evaluated. The novelty of the research should show that the elastic deformation of main component, caused by dynamic effects, has a significant influence to an accuracy of the precision systems, which are working in dynamic mode. The evaluation of the dynamic effects is necessary during the design and exploitation of precision measurement systems.

Precision Measurement System for the Calibration of Phasor Measurement Units

Phasor measurement units (PMUs) are used for monitoring, protection, and control of smart grids. Characterization of PMUs to national standards of measurement is important to assure reliability and consistency of PMUs across the industry and is required by documentary standards. At the National Measurement Institute, Australia, we have developed a calibration system to provide some calibration points for the characterization of PMUs under steady-state conditions that can be compatible with standard tests. This paper describes the operation and calibration of the system with emphasis on traceability to national standards of measurement.

EHealth Search Patterns: A Comparison of Private and Public Health Care Markets Using Online Panel Data.

BackgroundPatient and consumer access to eHealth information is of crucial importance because of its role in patient-centered medicine and to improve knowledge about general aspects of health and medical topics.ObjectivesThe objectives were to analyze and compare eHealth search patterns in a private (United States) and a public (United Kingdom) health care market.MethodsA new taxonomy of eHealth websites is proposed to organize the largest eHealth websites. An online measurement framework is developed that provides a precise and detailed measurement system. Online panel data are used to accurately track and analyze detailed search behavior across 100 of the largest eHealth websites in the US and UK health care markets.ResultsThe health, medical, and lifestyle categories account for approximately 90% of online activity, and e-pharmacies, social media, and professional categories account for the remaining 10% of online activity. Overall search penetration of eHealth websites is significantly higher in the private (United States) than the public market (United Kingdom). Almost twice the number of eHealth users in the private market have adopted online search in the health and lifestyle categories and also spend more time per website than those in the public market. The use of medical websites for specific conditions is almost identical in both markets. The allocation of search effort across categories is similar in both the markets. For all categories, the vast majority of eHealth users only access one website within each category. Those that conduct a search of two or more websites display very narrow search patterns. All users spend relatively little time on eHealth, that is, 3-7 minutes per website.ConclusionsThe proposed online measurement framework exploits online panel data to provide a powerful and objective method of analyzing and exploring eHealth behavior. The private health care system does appear to have an influence on eHealth search behavior in terms of search penetration and time spent per website in the health and lifestyle categories. Two explanations are offered: (1) the personal incentive of medical costs in the private market incentivizes users to conduct online search; and (2) health care information is more easily accessible through health care professionals in the United Kingdom compared with the United States. However, the use of medical websites is almost identical, suggesting that patients interested in a specific condition have a motivation to search and evaluate health information, irrespective of the health care market. The relatively low level of search in terms of the number of websites accessed and the average time per website raise important questions about the actual level of patient informedness in both the markets. Areas for future research are outlined.