High-precision Measurement System Research Articles

3D scanning techniques in power engineering

Information about component geometry is a key parameter for assessing residual life and monitoring degradation processes during the life cycle of a technology. High-precision optical measurement systems are complex metrology devices that enable the collection of complex data on the physical properties of components and their rapid evaluation in CAD-based programs. These solutions offer an analysis of changes in component characteristics over time and comparing them with as-built documentation. The quality of production can be evaluated by comparing the condition of the equipment with the product documentation or monitoring the influence of service conditions on the degradation of the equipment and the trend of future development of defects. All this in digital form of data, which enables new progressive approaches to repair and maintenance programs of monitored equipment. The use of advanced metrology and diagnostic systems and the procedures they offer can reduce the time required for measurement by conventional methods and multiply the data yield from metrology, which in conjunction with modern IT technologies can detect new degradation mechanisms and increase safety service and extend projected lifetime. Up-to-date technology data can significantly save on maintenance costs or even eliminate maintenance procedures. It also provides important data for the setup of LTO.

High-precision and wide-range temperature measurement and control system of satellite-borne calibration blackbody

The accurate measurement and control of blackbody temperature can play an important role in radiometric calibration. A novel circuit suitable for the aerospace environment is designed to measure and control the temperature of the blackbody. A coarse-fine measurement method considering the wire resistance and self-heating effect of the platinum resistance is presented to calculate the resistance values of the platinum resistors. The precision of temperature measurement is improved using a line fitting algorithm with error calibration and temperature drift error compensation. A fuzzy self-adaptive PID controller is designed to improve the temperature control effect. The performances of the developed system are implemented on an FPGA/A3PE3000-FG484I controller board. The test results show that the device temperature measurement precision can reach ±0.03K for the entire temperature range 238 K to 367 K, the temperature stability is better than 0.02 K/20 s, and the temperature uniformity is better than 0.1 K.

A high-precision experimental measurement system and method for the parahydrogen concentration and the Ortho-Para hydrogen catalyst's catalytic performance

An experimental system that combines the measurement of parahydrogen concentration with the assessment of ortho-para hydrogen catalyst's catalytic performance was created for this investigation. The concentration of parahydrogen was detected by a thermal conductivity detector integrated into the gas chromatograph. The catalyst sample and the generator of standard gas were integrated into one experimental setup for easier operation. Meanwhile, a new method for catalytic performance evaluation of ortho-para hydrogen catalyst was developed based on this system. This method can decrease test time and yield more valuable test results than the conventional way. Throughout the experiments, the system's dependability was increased by optimizing the utilization of the carrier gas. The deviation analysis and repeatability verification of the relevant test data showed that the relative standard deviation was less than 0.35% and the mean value of the variation coefficient was less than 0.20%, which demonstrated the method had high accuracy, stability, and reliability. Further studies have shown that the catalysts should be densely packed inside the converter and kept out of the air to maximize their catalytic activity. These pertinent findings regarding the application of ortho-parahydrogen catalysts in this study can guide the design of the ortho-parahydrogen converter in actual hydrogen liquefiers. Moreover, the method and the procedure proposed in this study may contribute to the optimization of the ortho-parahydrogen catalyst production process as well as the calibration of the parahydrogen concentration in liquid hydrogen products.

Measurement and analysis of impact dynamic parameters of micron-sized single particles using particle shadow velocimetry

The impact dynamics of micro-sized particles is still a fascinating topic of research, which can contribute to the understanding of the mechanisms of adhesion and rebound of these particles. A high-precision measurement system was developed that combines hardware, software, and numerical simulation methods to determine the impact dynamics parameters of micro-sized single particles under high temperature conditions by using Particle Shadow Velocimetry (PSV). The impact dynamic parameters of three standard particles (impact velocity, impact angle, coefficient of restitution, critical sticking velocity, etc.) were measured as examples to validate the reliability of this measurement system. The results demonstrated the reliability of the developed particle image processing algorithm. Corrections on the impact velocity and rebound velocity of small particles at low impact velocities were necessary. Particle size had a significant influence on the variation characteristics of the normal coefficient of restitution in particle impacts. A power function relationship between the critical sticking velocity and particle size was obtained. This paper provides a strong technical guidance for the future research on the impact dynamics of fly ash particles produced in the boiler field or other related fields.

Phase Retrieval Algorithm for Surface Topography Measurement Using Multi-Wavelength Scattering Spectroscopy

We are currently developing a high-precision and wide-range in-process surface topography measurement system using the laser inverse scattering method. In the laser inverse scattering method, a monochromatic plane wave is illuminated perpendicular to the target surface and the surface topography is measured by retrieving the phase distribution of the reflected light. However, the dynamic range of this method is limited to the sub-micrometer range because of phase wrapping during phase retrieval. In this paper, we propose a laser inverse scattering method using a multi-wavelength light source based on the fact that the phase of light is inversely proportional to the wavelength with the propagation distance as a coefficient. We also constructed a surface profilometer based on the proposed method and measured the profile of a single rectangular groove with a width of 50 µm and a depth of 2 µm. The dimensions of the measured profiles agree well with the nominal dimensions of the rectangular groove.

A high-precision TMR sensor array system for detecting surface and internal defects in thin sheet of steel

The online detection of small defects within thin steel holds significant importance in the field of steel manufacturing. This paper presents a high-precision flux leakage measurement system based on tunneling magnetoresistance sensors for detecting small defects in thin steel. We optimized the probe size and magnetic circuit design through numerical simulations and used the developed instrument to detect a standard mimicking through-hole defect plate, achieving a high signal-to-noise ratio and successfully detecting artificial defects small to a diameter of 50 μm. Additionally, we detected an actual internal defect in thin steel provided by the steel plant, meeting the required industrial accuracy. The data acquisition process in this study has been optimized to achieve real-time display and defect localization. The measurement scheme proposed in this paper has great potential for online monitoring of the thin steel production process.

Highly precise and stabilized measurement system for long-term oxygen measurement at atmospheric concentration level

We developed a high-precision oxygen measurement system with long-term stability using a magneto-pneumatic oxygen analyzer for atmospheric observations. A high precision of 1.4 per meg (which is less than the Network compatibility goal of the Global Atmosphere Watch programme of the World Meteorological Organization) was achieved in a 12-day continuous measurement by maintaining the sample-gas pressure and temperature constant, and by correcting the measured values using a predetermined temperature correction factor. The oxygen measurement system does not require a control gas to compensate for signal drift. The calibration cycle was evaluated to be one week based on the Allan standard deviation. This indicates that the system can measure continuously for over one year without changing the cylinders for calibration gases. The developed oxygen measurement system is likely to be suitable for in situ atmospheric observation because of its high measurement precision and capability to use fewer high-pressure gas cylinders.

A Study on the Contact Characteristics of Tires-Roads Based on Pressure-Sensitive Film Technology.

Tire-road characteristics are a critical focus of research in the automotive and transportation industries. On the one hand, the research can help optimize tires' structural design; on the other hand, it can analyze the mechanical response of the pavement structure under the vehicle load. In addition, the non-uniformity distribution of the tire ground stress will also have a direct impact on the skid resistance, which determines the driving safety. Due to the limitation of testing technology, the measurement of tire ground pressure was mainly carried out on a flat test platform, ignoring the roughness of the actual pavement surface texture. The tire-road contact characteristics research on the macro-texture and micro-texture of asphalt pavement needs to be broken through. A high-precision pressure-sensitive film measurement system is utilized to examine the actual contact characteristics between two types of automobile tires and three types of asphalt pavement in this paper. The influence law of pavement texture and patterned tires on the contact area and stress was explored, and the concentration effect of tire-road contact stress was evaluated. The results indicate that the contact area of grounding tires exhibits a nearly linear relationship with tire inflation pressure and load. Notably, the change in load has a more significant influence on the contact area than tire inflation pressure. On asphalt pavement, the contact reduction rate decreases by approximately 5-10% for block pattern tires and 10-15% for longitudinal pattern tires. Furthermore, as the texture depth of the pavement increases, the contact area between tires and the pavement texture decreases. The actual tire-road interface experiences significant stress concentration due to the embedding and meshing effects between the tire and road surface. Even on a flat steel surface, the peak stress at the edge of the tread block exceeds the 0.7 MPa design load, which is about 2.5-3 times higher than the design uniform load. The peak stress between the tire and asphalt pavement reaches 4-10 times the design uniform load, with a rising trend as the pavement texture depth increases. This study can provide relevant experimental technical support for tire design and functional design of asphalt pavement.

Reflection-based vision guide method for coarse alignment of vector measurement during the satellite assembly, integration, and test process.

Vector measurement is a vital measurement item during the satellite assembly, integration, and test (AIT) process. With the increasing popularity of commercial spaceflight, the development cycle of a satellite is shorter, and the number of satellites has been growing rapidly. The traditional on-site vector measurement method is inefficient and significantly affects the development cycle of the satellite. Therefore, it is of utter importance to propose an online high-precision automatic vector measurement system. The most challenging step of the online automatic vector measurement is coarse alignment because a cubic prism must be identified, and the normal direction of its surface must be calculated at a certain precision in the unstructured environment during the coarse alignment step. A reflection-based vision guide method was proposed to identify and calculate the normal direction of the cubic prism. The working principle and advantage of the proposed vision guide system were described in detail. What is more, the calibration and calculation methods of the proposed vision guide system were also presented. Finally, experiments were conducted to verify the effectiveness of the proposed method.

A Real-Time Measurement Method and System for the Harvesting Area of a Grain Combine Harvester

A real-time system for measuring harvesting area is crucial for cross-regional operation. In response to the current situation where significant errors often occur in measuring the areas of small and irregular fields, we designed a low-cost and high-precision online real-time measurement system for the harvesting area of grain combines. The real-time measurement hardware system for measuring area was designed using an STM32 microcontroller as the core unit. The system was developed using three modes: intelligent measurement, circular measurement, and fusion measurement. Simulation and field experiments were conducted to verify the performance of the system. The experimental results showed that in the field simulation experiment with four differently shaped operating areas, the average accuracy of the intelligent mode reached 93.76%, and the average accuracy of the circular mode reached 95.48%. In the field experiments, the average accuracy of the intelligent mode reached 95.09%, the average accuracy of the circular mode reached 95.74%, and the average accuracy of the fusion measurement mode reached 98.01%. Therefore, the real-time measurement system for the harvesting area of a grain combine harvester designed in this study has high accuracy when measuring the area of small and irregular farmland, hence meeting the requirements of the design objectives.

Hundred-femtosecond-level concise optical time delay measurement system based on linear optical sampling

Fiber-delay measurement is one of the key fundamental technologies in numerous fields. Here, we propose and experimentally demonstrate a high-precision and concise optical time delay measurement system based on the technique of linear optical sampling, reaching the precision better than 100 fs under averaging. The use of only two optical frequency combs without locking the carrier-envelope-offset frequency greatly simplifies the structure of the time-delay measurement system. We also experimentally investigate the current limitations on the precision of the system. The timing jitter noises of two sources are mainly non-common mode and are both restricted to the frequency sources. Our results indicate that the proposed device can measure fiber length fluctuations below 10 µm, paving the way for further analyses of the external disturbances on the fiber link.

The Influence of Geometrical Parameters on Temperature Deformation of Spherical Honeycomb Sandwich Structure

As a reflector of the high-precision measurement system, the reflecting surface RMS has a significant impact on the accuracy of the entire system. Currently, studies on honeycomb sandwich structures mainly focus on optimization with lightweight as the goal and stiffness and strength as constraints. And studies on temperature deformation are limited. Consulting the honeycomb sandwich equivalent theory, this paper has studied the influence of geometric parameters of honeycomb sandwich structure on the reflecting RMS in different temperature fields. In global temperature fields, the reflecting surface RMS is linked to curvature radius R, temperature changes, and the length a closely. The height mainly causes the translation of the reflecting surface in the Z direction. In temperature gradient fields, the reflecting surface RMS is linked to the height h, temperature gradient, and length a closely. And the curvature radius R has little effect.

A method for measuring and calibrating the thickness of thin films based on infrared interference technology

Transparent thin films are critical industrial components widely used in advanced optics, microelectronics and materials science, among other relevant fields. The rapid and stable measurement of sub-micron industrial film thickness is of particular importance. In this study, a novel method based on the principles of infrared interference and laser profilometry is proposed to calculate the periodogram of the original spectrum and accurately extract the maximum frequency. In addition, a high-precision, compact and low-cost thin-film thickness measurement and calibration system is developed. This system achieves accurate measurement of single-layer film thickness and adapts to correct errors caused by slight tilt due to mechanical vibration or misalignment during film placement. Experimental data show that, compared to conventional infrared interference thickness measurement systems, the use of the proposed maximum frequency extraction algorithm improves measurement accuracy by approximately 90% and stability by approximately 70%. Furthermore, even when measuring the thickness of films with inclined components, the use of the constructed thin film thickness measurement and calibration system provides equivalent results.

Simultaneous detection of CO2/CH4 based on off-axis integrated cavity output spectroscopy and time-division-multiplexing-based wavelength modulation spectroscopy

A highly sensitive dual gases detection system was established for detecting the concentrations of carbon dioxide (CO2) and methane (CH4) simultaneously based on off-axis integrated cavity output spectroscopy (OA-ICOS) technology. Two Distributed Feedback (DFB) lasers with central wavelengths of 1580 nm and 1653 nm were used as the light sources of the system. A time-division-multiplexing-based wavelength modulation spectroscopy (WMS) method was used to scan the current of lasers for improving the signal-to-noise ratio of the system and getting the optimal modulation amplitudes of CO2 and CH4 simultaneously. In addition, the cavity mode noise was suppressed by radio frequency (RF) white noise loading and laser current to further improve the measurement accuracy. Allan deviation analysis indicates that measurement precision of 0.483 ppm for CO2 and 1.37 ppb for CH4 was achieved by averaging up to 993 s and 1093 s respectively. This compact and high-precision measurement system is suitable for measuring atmospheric greenhouse gases.

Measurement and Correction of Pointing Error Caused by Radio Telescope Alidade Deformation based on Biaxial Inclination Sensor.

One of the key reasons for the deterioration of antenna pointing accuracy for radio telescopes is the deformation and tilt of antenna alidades, which primarily result from track unevenness and thermal gradients. A high-precision inclinometer measurement system is installed to investigate the tilt of the antenna alidade and the pointing errors caused thermally. An environment control box with a leveling base was designed to reduce the interference of the external environment, which proved to be effective in guaranteeing the zero-point stability and repeat accuracy of the inclinometer. The tilt of the alidade caused by the track unevenness was measured by a test of slowly rotating the antenna along the azimuth at windless nighttime. A 5-day antenna stationary test and a 48 h astronomical pointing error measurement were performed, which proved the inclinometer measurement system is capable of measuring the thermally induced inclinations with acceptable accuracy. Through a preliminary compensation experiment, the pointing error is compensated from 37″ to 12″, which shows that the application of the system has a good effect on improving the pointing accuracy of the antenna. The system with high measurement accuracy, good system stability, and low computational complexity, proves an effective tool for the radio telescope to solve the problem of real-time measurement and compensation for antenna pointing errors.

Research on the muzzle vibration displacement test method of large-caliber rifled gun based trinocular vision

To address the problem of inaccurate muzzle vibration displacement measurements caused by the twisting of the barrel at the moment of firing of large-caliber rifled gun, a vibration displacement test method of large-caliber rifled gun based trinocular vision is proposed. A high-precision measurement system for muzzle vibration displacement based on an orthogonal imaging method with three high-speed cameras has been built. Three high-speed cameras are placed at the side and rear of the gun at orthogonal angles to each other to collect two-dimensional digital images of the gun muzzle area. Accurate displacement of the muzzle height, azimuth and recoil direction is derived by image processing techniques and multi-dimensional displacement decoupling methods. In addition, the three cameras can realize the online self-verification of parameters such as ‘recoil’ and ‘twist’. The three-dimensional vibration displacement and torsion parameters of the muzzle of a 155mm gun were obtained by a test of firing range. The test results proved the validity and accuracy of the method for the muzzle vibration displacement of rifled gun.

Udo Krüger Charts TechnoTeam's Journey

Udo Krüger Charts TechnoTeam's Journey

Adaptive Buffer Capture and Storage for High-Speed Cameras

The output speed of a high-resolution camera with a fast frame rate is high, reaching 800 MB/s or even more. Consequently, the abundant data recorded can easily cause data overflow during transmission and frame loss during storage. To address this problem of data overflow and frame loss while achieving reliable acquisition rates, herein, we design a high-speed video adaptive transmission and storage method based on the camera link transmission protocol. The system uses the camera link transmission protocol and high-speed cameras for data acquisition. During data transmission, memory space is employed as the data buffer pool, an adaptive memory buffer pool is designed using the hardware and acquisition parameters, and a circular read/write buffer, combined with a block device read/write method, is used inside the buffer pool for data transmission. For data storage, input/output completion port asynchronous storage mixed with frame sequence number filtering is employed to write data, and the adaptive buffer of the hard disk is used to achieve efficient data writing. The experimental results reveal that the proposed method can realize efficient and stable writing of data on conventional industrial cameras based on the camera link interface, effectively addressing the problem of frame loss during data storage. Moreover, the stored data can be transferred efficiently with less resource occupation, thereby meeting the application requirements of high-precision vision measurement systems and demonstrating broad application value.

Range Extension for Large-Scale Robotic Precision 3-D Measurements in Vibration-Prone Environments

This paper presents a range extension concept for a high-precision robotic inline 3D measurement system. A scanning confocal chromatic sensor (SCCS) is integrated with a magnetically levitated and actuated measurement platform for the acquisition of 3D images with sub-micrometer resolution, enabled by means of active sample-tracking to compensate for relative motion between the SCCS and the sample. Based on an intermediate range extension approach, the lateral scan area is pre-extended to enable a robotic repositioning of the 3D measurement module, ensuring sufficient overlap regions between the individual 3D image frames. Experimental results show that the proposed concept extends the 3D measurement modules’ measurement range by about 80% of the lateral scan area within an acquisition time of about 90 s. Range-extended 3D measurements directly in a vibration-prone environment reveal that 97% of disturbing relative motion between the SCCS and the sample are compensated by the active sample-tracking approach. In this way, lab-like conditions for the SCCS are established directly in an industrial production line and, improving the measurement error by three orders of magnitude down to several tens of nanometers.

Ambiguity-Fixing in Frequency-Varying Carrier Phase Measurements: Global Navigation Satellite System and Terrestrial Examples

<h3>Abstract</h3> Carrier phase signals are considered among the key observations in global navigation satellite systems (GNSSs) and several other high-precision interferometric measurement systems. However, these ultra-precise measurements are not fully exploited when the integerness of their inherent ambiguities is discarded during the estimation process. Provided that the integer-estimable functions of their phase ambiguities are properly identified, integer ambiguity resolution (IAR) can be utilized to benefit their parameter solutions. For the GNSS code division multiple access systems with transmitters that broadcast carrier phase signals on identical frequencies, these integer-estimable functions have been characterized and are well-known as double differenced ambiguities. However, this is not the case with “frequency-varying” carrier phase signals that are broadcast by GLONASS satellites, Low-Earth-Orbiting communication satellites, or cellular long-term evolution (LTE) transmitters. This study aims to present full-rank models that can be used to identify integer-estimable ambiguity functions, thereby bringing the observation equations of frequency-varying carrier phase measurements into an IAR-applicable form. Our analytical results are supported by several numerical examples, including GNSS and terrestrial-based IAR as well as a new set of “inter-frequency” integer ambiguities that this study discovers in Galileo multi-frequency carrier phase signals.