High Efficiency Measurement Research Articles

The Research on the Mobile Measuring Robot Technology

At present, the traditional construction method of engineering measurement relies on the cooperation of many people, who need to manually level the measuring instruments to measure and set them point by point, which has low construction efficiency and cannot meet the application requirements of modern engineering construction measurement. Therefore, it is necessary to develop mobile measuring robots. This paper mainly studies the model, operation flow, measurement accuracy, and data stability of the mobile measuring robot. The results show that the mobile measuring robot has high measurement efficiency, measurement accuracy, and data stability, and can replace the traditional survey for measurement construction.

Development of a Three-Dimensional Optical Verification Technology without Environmental Pollution for Metal Components with Different Surface Properties.

Nowadays, the optical measuring approach is widely used in the precision machining industry due to high measurement efficiency. In the industry, measuring devices play a crucial role in the field of quality assurance. In practical engineering, the green measurement approach indeed plays an important role in the industry currently. In this study, a state-of-the-art green technique for three-dimensional (3D) optical measurements without environmental pollution is demonstrated, which is an environmentally friendly optical measurement method. This method can perform precise optical measurement without matte coatings. This work dealt with the possibility of measuring four metal components that were not sprayed with anything. The differences in the optical measurement results between with and without matte coatings were investigated and analyzed. It was found that the research result has practical value in the precision machining industry because average size errors of the four measurement objects with different surface properties can be controlled at about 3 µm, 0.1 µm, 0.5 µm, and 9 µm. A technical database with industrial value was established for optical measurements of metal components with different surface properties without matte coatings, which can serve as an alternative to the conventional 3D optical measurement.

Power-Independent Microwave Instantaneous Frequency Measurement Based on Combination of Brillouin Gain and Loss Spectra

Photonics-assisted microwave instantaneous frequency measurement (IFM) is considered as a promising technique for detecting an unknown radio-frequency (RF) signal, which has advantages of broad frequency measurement range and fast processing speed. Up to date, there is no photonics-assisted IFM system that can essentially measure an unknown RF signal time-frequency information with power fluctuating seriously. Moreover, the measurement accuracy and frequency modulation recognition are not as good as those of traditional electronic methods. Here, we propose an IFM scheme based on the combination of Brillouin gain spectrum (BGS) and Brillouin loss spectrum (BLS), which is RF-power-independent with high measurement efficiency. The combination of BGS and BLS to construct the amplitude comparison function (ACF) can reduce the influence of RF signal power fluctuation within 21.27 dB by single-shot measuring. When an appropriate frequency interval with frequency domain monotonous power of microwave comb signal is modulated on the pump lightwave, the IFM accuracy of the unknown signal reaches about 1 MHz. After the initial calibration of the system, it can recognize the time-frequency variation of single tone signal, linear frequency modulated signal (LFM), nonlinear frequency modulated signal (NLFM), and Costas signal. This scheme will help to promote the application of the IFM in the field of spectrum reconnaissance and reception.

An Environmentally-Friendly Three-Dimensional Computer-Aided Verification Technique for Plastic Parts.

Plastic components play a significant role in conserving and saving energy. Plastic products provide some advantages over metal, including reducing part weight, manufacturing costs, and waste, and increasing corrosion resistance. Environmental sustainability is one of the sustainable development goals (SDGs). Currently, the non-contact computer-aided verification method is frequently employed in the plastic industry due to its high measurement efficiency compared with the conventional contact measuring method. In this study, we proposed an innovative, green three-dimensional (3D) optical inspection technology, which can perform precise 3D optical inspection without spraying anything on the component surface. We carried out the feasibility experiments using two plastic parts with complex geometric shapes under eight different proposed measurement strategies that can be adjusted according to the software interface. We studied and analyzed the differences in 3D optical inspection for building an empirical technical database. Our aim in this study is to propose a technical database for 3D optical measurements of an object without spraying anything to the component’s surface. We found that the research results fulfilled the requirements of the SDGs. Our research results have industrial applicability and practical value because the dimensional average error of the two plastic parts has been controlled at approximately 3 µm and 4.7 µm.

Technical note: Accelerator mass spectrometry of <sup>10</sup>Be and <sup>26</sup>Al at low nuclide concentrations

Abstract. Accelerator mass spectrometry (AMS) is currently the standard technique to measure cosmogenic 10Be and 26Al concentrations, but the challenge with measuring low nuclide concentrations is to combine high AMS measurement efficiency with low backgrounds. The current standard measurement setup at ANSTO uses the 3+ charge state with Ar stripper gas at 6 MV for Be and 4 MV for Al, achieving ion transmission through the accelerator for 10Be3+ and 26Al3+ of around 35 % and 40 %, respectively. Traditionally, 26Al measurement uncertainties are larger than those for 10Be. Here, however, we show that 26Al can be measured to similar precision as 10Be even for samples with 26Al / 27Al ratios in the range of 10−15, provided that measurement times are sufficiently long. For example, we can achieve uncertainties of 5 % for 26Al / 27Al ratios around 1×10-14, typical for samples of late Holocene age or samples with long burial histories. We also provide empirical functions between the isotope ratio and achievable measurement precision, which allow predictive capabilities for future projects and serve as a benchmark for inter-laboratory comparisons. For the smallest signals, not only is understanding the source of 10Be or 26Al background events required to select the most appropriate blank correction method but also the impact of the data reduction algorithms on the obtained nuclide concentration becomes pronounced. Here we discuss approaches to background correction and recommend quality assurance practices that guide the most appropriate background correction method. Our sensitivity analysis demonstrates a 30 % difference between different background correction methods for samples with 26Al / 27Al ratios below 10−14. Finally, we show that when the measured signal is small and the number of rare isotope counts is also low, differing 26Al or 10Be concentrations may be obtained from the same data if alternate data reduction algorithms are used. Differences in the resulting isotope concentration can be 50 % or more if only very few (≲ 10) counts were recorded or about 30 % if single measurement is shorter than 10 min. Our study presents a comprehensive method for analysis of cosmogenic 10Be and 26Al samples down to isotope concentrations of a few thousand atoms per gram of sample, which opens the door to new and more varied applications of cosmogenic nuclide analysis.

Shank length and circumference measurement algorithm of breeder chickens based on extraction of regional key points

The phenotypic parameters of breeder chickens are the external expression of their genetic genes. Accurate and efficient acquisition of chicken phenotypic parameters is a key technology in poultry breeding. However, the traditional manual measurement method is time-consuming and laborious, and the measurement error is large, which seriously affects the effect and efficiency of poultry breeding. Therefore, in this paper, Xinghua chicken as the research object, combining computer vision technology and deep learning algorithm, proposed the shank length and circumference measurement algorithm (SLCM) of breeder chickens. The algorithm firstly detected and extracted the region of chicken claw and shank bottom base by YOLOV5 algorithm. And then extracted the key points of shank length and circumference measurement based on the pixel distribution features of row direction and column direction in this region, and finally calculated the values of shank length and circumference. The test results of SLCM algorithm show that compared with the traditional manual measurement method, the Pearson correlation coefficient of shank length and circumference measured by algorithm is 0.8722 and 0.8869. Besides, this algorithm not only has smaller standard deviation (standard deviation of shank length is 1.35 mm, and shank circumference is 0.25 mm) and coefficient of variation (the mean coefficient of variation of shank length is 0.02, maximum is 0.06; and the mean coefficient of variation of shank circumference is 0.01, maximum is 0.03), but also has higher measurement efficiency. This research provided reference and basis for the accurate measurement of phenotypic parameters of breeder chickens and had important significance for poultry breeding.

Measurement and modeling of reflection characteristics of hole inner surface based on endoscopic image

Reflection characteristic is the law of specular and diffuse reflection after receives light of the surface, usually expressed by the ratio of irradiance of incident direction to the emissivity of observation direction, namely bidirectional reflection distribution function (BRDF). A method to measure BRDF for hole inner surface based on the endoscope image and morphology is proposed, which established the relationship between BRDF and morphology. Taking stainless steel and galvanized internal threaded as an example, the axial images in the holes are collected, and the BRDF of internal surface is calculated through the image brightness and the normal direction. The distribution characteristics of BRDF on the inner surface of different materials are analyzed. Based on the Phong model, the inBRDF parameter model of the inner surface is established. Research shows that the inBRDF model is consistent with measured results, and the average fitting error of the two materials is only 6.22%. The inBRDF method of hole inner surface proposed in this paper has high measurement efficiency and strong universality of equipment, and it is preferred to be applied on hole inner surface quality detection accordingly.

Off-axis digital holographic decarrier phase recovery algorithm combined with linear regression

Benefitting from the high measurement efficiency, off-axis digital holography (DH) has become a most powerful DH technique for fast and high-accuracy measurement. Owing to the carrier frequency, the real image can be isolated easily in the Fourier spectrum of one off-axis hologram, so that the Fourier transform algorithm (FTA) is the most widely used algorithm for off-axis DH to realize the phase retrieval. In the FTA, one of the most important tasks is to figure out the accurate peak position of the real image and then shift the real image to the center of spectrum to remove the carrier. However, owing to the digitalization of the hologram, the peak position of the real spectrum is always not located at an integral pixel position in the practical applications, resulting in carrier residuals, thereby lowering the retrieval quality. Much work on accurately determining the peak position has been conducted to suppress the carrier residuals, such as by using the spectrum centroid method and zero padding. However, those estimation algorithms can achieve only satisfied accuracy in some situations. Then, spatial carrier phase shift (SCPS) is utilized to expand the utilization of space-bandwidth and avoid the spectrum leakage caused by band-pass filtering. The SCPS decomposes one off-axis hologram into several sub-holograms, in which the carrier induces the phase shifts between sub-holograms. Many on-axis phase retrieval algorithms are combined with SCPS to retrieve the phase from one off-axis hologram. However, the retrieved phase is usually composed of the sample phase and the carrier, so the accurate carrier information is also required to remove the carrier and obtain the correct reconstructed phase. In this paper, an accurate phase retrieval with carrier removal from single off-axis hologram by using the linear regression is proposed to achieve the simultaneous phase retrieval and carrier removal. In this method, four phase-shifted sub-holograms are extracted first from one off-axis hologram by SCPS. Since the phase shift between sub-holograms is linearly proportional to the carrier, the linear regression can be combined with least-square method to retrieve the phase and carrier simultaneously. Both the simulation and experimental results show that the proposed method can determine the carrier accurately and obtain correct phase without carrier. We believe that this proposed method can be applied to practical measurement.

RETRACTED ARTICLE: A full freedom pose measurement method for industrial robot based on reinforcement learning algorithm

In this current era, the field of robotics has made much advancement and has also produced novelties than any other advanced research areas. The usage of robots has become an imperative part of the defense-oriented applications. The missions which are difficult to be performed by human beings can certainly be accomplished by the robots nowadays. The most crucial part for an industrial- and defense-based robot is to perform pose movements accurately for optimal usage of robotics as a replacement of human beings. This paper proposes a comprehensive introduction to the proposed hybrid approach PSO–RL which uses reinforcement learning (RL) and Particle swarm optimization (PSO). It summarizes the usage of proposed PSO-RL for pose measurement of robots in defense and industrial manufacturing systems. The hybrid PSO–RL is a promising technique for measuring poses in robots with accuracy and for optimizing obstacle avoidance error. In this paper, robot’s core movements are analyzed; speed of movements is given importance, and an attempt is made to provide more accurate moves with high precision. In order to optimize the efficiency of robotic operations, a full freedom pose measurement method based on PSO–RL is proposed. By using the characteristics of two-wheel independent driving industrial robot, the performance of the robot in three moving modes is evaluated. The experimental results show that the proposed PSO-RL method has the advantages of high accuracy, high measurement efficiency, high success rate of grabbing and avoiding obstacles. It outperforms the existing methods such as least square method and micro-displacement cyclic correction method with respect to maximum error, RMSE score and time complexity.

High-Throughput Chiral Molecule Determination Based on Multi-Channel Weak Measurement

A multi-channel high-throughput chiral molecule determination method based on weak value amplification (WVA) is proposed for the first time. This method can be used for high-throughput and high-precision determination of chiral molecule. Through the design of multi-channel weak measurement system, we realized the real-time, high-throughput, high-sensitivity and high-resolution detection of chiral molecules by selecting proper measurement states. In this work, we have realized a sensitivity of 11.8 nm/° and a resolution of 3.13 × 10-4° for measuring optical rotation. Moreover, the proposed method is successfully applied for detection of lactose content in milk samples. Furthermore, the system has the advantages of simple and robust real-time detection settings, strong stability, high measurement efficiency and good scalability. This method has important significance in clinical diagnosis, food safety and biological system.

3-D shape reconstruction of non-uniform reflectance surface based on pixel intensity, pixel color and camera exposure time adaptive adjustment

High dynamic range 3-D shape measurement is a challenge. In this work, we propose a novel method to solve the 3-D shape reconstruction of high-reflection and colored surfaces. First, we propose a method to establish a fast pixel-level mapping between the projected image and the captured image. Secondly, we propose a color texture extraction method using a black-and-white (B/W) camera and a pixel-level projection color adjustment method. Third, we give an optimal projection fringe modulation/background intensity ratio. Fourth, we propose a method for estimating the reflectivity of the object surface and ambient light interference, and a method for adjusting the projection intensity at the pixel level and a method for estimating the optimal exposure time. Experiments show that, compared with the existing methods, the proposed method not only can obtain high-quality captured images, but also has higher measurement efficiency and wider application range.

On-machine measurement method for the geometric error of shafts with a large ratio of length to diameter

For shafts with a large ratio of length to diameter, the existing measurement method mainly uses a contact coordinate machine. But machining errors have a strong influence on the offline measurement results, and the accumulation errors of the measurement system also make the measurement datum difficult to identify. For this reason, a new on-machine measuring method is proposed based on the spatial analytical geometry theory to achieve the measurement of the shape and position tolerance of shafts. Through the method, the measurement system combines the line laser measuring instrument and the laser displacement sensor together. Then, the ideal central axis of the workpieces can be obtained and serve as a datum. Finally, the on-machine non-contact measurement of large-size shafts with geometric errors is realized with high measurement accuracy (<0.01 mm), high measurement efficiency (time <10 mins), and strong robustness (insensitive to installation error and measuring environment).

High-Precision Method for Estimating the Three-Dimensional Green Quantity of an Urban Forest

Forests are an important component of urban ecosystems that offer a variety of ecological services; however, there are few reports on the application of high-precision three-dimensional (3D) laser-scanned point cloud data to quantify the 3D green volume. To quantitatively study the 3D green quantity of urban forests in Xi'an, China, aerial remote sensing and high-precision 3D laser-scanned point cloud data were used to build an estimation model using a differential method. The results show that the 3D green quantity model has a high estimation accuracy of 88.07%, with an R value of 0.89, and can be used as an inverse model for estimating the 3D standing wood volume. The method can be automated for data processing and has a high measurement efficiency, making it applicable to real situations and significantly improving the measurement accuracy of single-tree 3D green quantification. The total 3D green quantity in the main urban area of Xi’an is 37,475,294.7 m3, where areas containing the greatest green volume follow the order scenic sites > cultural and educational areas > traffic routes > residential areas > industrial areas. This method can be used to improve urban design, policy making, and healthy urban forests.

Novel Method for Measuring the Grounding Resistance of Towers With Short Electrode Wire

The three-electrode method is the most commonly used grounding resistance measurement method. But the electrode wire of the three-electrode method is too long to be used in mountainous areas or densely built areas. Therefore, it is of great application value to effectively shorten the electrode wire under the condition of ensuring measurement accuracy. In this article, a novel method for measuring the grounding resistance of towers with short electrode wire is proposed. Based on the connectivity of soil inside and outside the tower foundation, the limited space inside the tower foundation is fully used to arrange the electrodes. The principle of arranging electrodes inside the tower foundation to measure the grounding resistance is deduced in detail. The calculation method of the compensation point position and measurement error is studied. The best way of arranging electrodes is proposed. Through simulation experiments and field tests, we confirmed that the measurement accuracy of this novel method is similar to that of the three-electrode method. Its electrode wire length is shorter than the three-electrode method and other improved methods. Only the length of electrode wire needs to be the same as the length of the grounding conductor, and the measurement error can be controlled at about 3%. The novel grounding resistance measurement method has a wider application range and higher measurement efficiency.

Non-contact measurement method of coaxiality for the compound gear shaft composed of bevel gear and spline

Aiming at the rapid coaxiality measurement of compound gear shaft, a non-contact optical measurement scheme is proposed in this paper. According to the data points of cross-section obtained by laser displacement sensors, data points of the gear top are separated tofit the center of the section. Four circlefitting methodsare compared, and the least square circle (LSC) is selected to calculate the center coordinates. The particle swarm optimization (PSO) is used to fit the axis of the minimum containment cylinder of the centers of the spline, which is taken as the reference axis. According to the criterion of minimum containment area, the coaxiality error of bevel gear relative to spline is evaluated. The test results show that the proposed method is feasible with high measurement precision (accurate to 0.01 mm), high measurement efficiency (measuring time <2 mins) and automatic control ability. The error range of 10 groups of measurement experiment is less than 0.065 mm.

Boundary Point Measurement Using Visual Technique

The global positioning system real-time kinematic (GPS-RTK) instrument is a commonly used instrument to obtain GPS coordinates in cadastral surveying, but its use is limited to unshielded environments. This study proposes a new method based on a visual simultaneous localization and mapping (SLAM) algorithm that uses a stereo-camera to replace traditional methods. The benefits of our method are a higher measurement efficiency, fewer required professionals, and fewer restrictions on the operating environment compared with the traditional RTK and total station method. First, we propose a robust non-planar camera calibration algorithm that uses three non-planar chessboards to obtain intrinsic parameters of a stereo-camera to improve the accuracy of the measurement. Second, we propose a detailed algorithm that uses a stereo-camera and known GPS coordinates to obtain unknown GPS coordinates. Using experiments, we demonstrated the effectiveness and stability of our method to provide accurate GPS coordinates.

Simulate New Near Equatorial Satellite System by a Novel Multi-Fields and Purposes Remote Sensing Goniometer

Researchers in the remote sensing field use different types of images from satellite systems and simulator devices, such as goniometers. However, no device can simulate the new generation of optical satellite system called near-equatorial satellite system to perform different kinds of remote sensing applications in equatorial regions. This study proposed a newly invented laboratory and fieldwork goniometer designed to simulate and capture intensity variation and measure the bidirectional spectral reflectance of earth surface. The proposed goniometer is a multi-purpose and multi-field device. It is able to simulate different satellite systems and measure the intensity variation and spectral reflectance of earth’s surface features with freely azimuth and zenith angles of sensors and illumination source in fieldwork and/or laboratory. However, the system of invention is focusing on specific satellite orbital to work with the parameters and properties of NEqO satellite system in order to obtain NEqO system imagery for performing different applications such as geometric correction, relative radiometric normalization and change detection for future work. The significant of this invention is that most of the invented goniometers of remote sensing are able to work just in field or just in laboratory and use, carry just optical sensor or hyperspectral sensor. Specifically, our invention can do all these functions that are not available in existing goniometers. The proposed device offers several advantages, namely, high measurement speed, flexibility, low cost, efficiency, and possible measurement depending on the free zenith/azimuth angles of sensors and illumination sources. The proposed goniometer includes ten parts, and two different sensors (optical and hyperspectral).

Experimental progress of noise measurements in reverberation tanks

The methods and means for measuring the radiation characteristics of underwater sound sources have been developed under the conditions of reverberant tanks. From the perspective of experimental research, this paper introduces the methods of measuring the radiated sound power of steady-state sound sources and transient sound sources in reverberation tanks. The experimental subjects include the typical transducer under steady-state excitation, the cylindrical shell under steady-state excitation, the transient CW pulse sound signal and the underwater transient spark sound. The measurement principles, experimental system and measurement accuracy involved in each experiment are also listed. The experimental results show that the reverberation tank is an effective experimental device for measuring the acoustic characteristics of underwater sound sources, which has the advantages of simple experimental conditions, high measurement efficiency and strong tolerance for different types of sound sources.The methods and means for measuring the radiation characteristics of underwater sound sources have been developed under the conditions of reverberant tanks. From the perspective of experimental research, this paper introduces the methods of measuring the radiated sound power of steady-state sound sources and transient sound sources in reverberation tanks. The experimental subjects include the typical transducer under steady-state excitation, the cylindrical shell under steady-state excitation, the transient CW pulse sound signal and the underwater transient spark sound. The measurement principles, experimental system and measurement accuracy involved in each experiment are also listed. The experimental results show that the reverberation tank is an effective experimental device for measuring the acoustic characteristics of underwater sound sources, which has the advantages of simple experimental conditions, high measurement efficiency and strong tolerance for different types of sound sources.

Design and Application of Satellite Automatic Angle Measurement System Based on Robot

In order to achieve the on-orbit performance of the satellite, the installation positions of some instruments on the satellite are measured when the satellite is integrated on the ground, to ensure the installation position and the accuracy meet the design requirements. With the development of aerospace industry, more and more satellites have the characteristics of difficult development, short development time and heavy position measurement task. In view of the mass produce of satellites, an automatic angle measurement scheme based on robots is designed and applied. Giving full play to the advantages of automation and high measurement efficiency of robots, this system effectively improves the measurement efficiency and reducing the occupancy of personnel.

Development of a rapid measurement system for coarse aggregate morphological parameters

Morphological parameters of coarse aggregates, including the angularity index (AI), flat and elongated ratio, flatness ratio, and sphericity, strongly affect the performance of asphalt concrete. A device must be developed to efficiently and accurately measure these parameters. Herein, a charge-coupled device camera and a linear profile scanner are combined to evaluate the parameters. The AI is calculated using three methods. The results show that the fitted-ellipse method provides superior results among the three AI measurement methods. Moreover, the use of a linear profile scanner improves the AI measurement accuracy. Therefore, the proposed combination has high measurement efficiency and is suitable for batch inspections.