Speed Measurement System Research Articles

Vehicle-Deployed Off-Axis Integrated Cavity Output Spectroscopic CH4/C2H6 Sensor System for Mobile Inspection of Natural Gas Leakage.

A vehicle-deployed parts-per-billion in volume (ppbv)-level off-axis integrated cavity output spectroscopic (OA-ICOS) CH4/C2H6 sensor system was experimentally presented for mobile inspection of natural gas leakage in urban areas. For the time-division-multiplexing-based dual-gas sensor system, an antivibration 35-cm-long optical cavity with an effective path length of ∼2510 m was fabricated with a high-stability temperature and pressure control design. An Allan deviation analysis yielded a minimum detection limit of 0.2 ppbv for CH4 detection and 10 ppbv for C2H6 detection for a 1 s averaging time. A natural gas leakage source location algorithm was proposed using an improved hybrid Nelder-Mead simplex search method and a particle swarm optimization (NM-PSO) algorithm. For field industrial application, the accuracy of the sensor system and leakage source location algorithm was confirmed through a CH4/C2H6 cylinder leakage experiment on the campus. Furthermore, through natural gas pipeline network inspection measurements in urban areas, three types of leakage sources, including natural gas, biogas, and possible leakage source were respectively located and confirmed using the global positioning system and wind speed and direction measurement system, verifying the reliability and potential application of the vehicle-deployed inspection system for future natural gas pipeline leakage monitoring.

Bearing inner race fault detection and size estimation using the variable reluctance sensor

The variable reluctance sensor (VRS) has been widely used in the speed measurement system in the fields of automobile, helicopter, and ship, because of its high robustness. In recent years, most studies have verified the effectiveness of the application in rotor torsional vibration measurement and blade monitoring by the VRS. However, there is less research devoted to the VRS in bearing fault diagnosis, and its influencing mechanism between bearing faults and signal characteristics is not clear. In this paper, the raw signal of the VRS is used for bearing diagnosis. The mechanism of bearing partial fault signal response is analyzed by establishing the bearing inner ring fault model and the sensor signal response model. The characteristics of the VRS signal are given and verified by experiments. The results show that the gearwheel tooth-pass frequency is modulated by the bearing fault characteristic frequency, and there is an obvious double peak phenomenon in the high-frequency part. Moreover, the fault data with widths of 1 mm and 2 mm are analyzed by using the interval time of double peak. It is found that the fault sizes estimated are close to the actual defect size, and have small standard deviations. The original signal of the VRS has great potential in bearing diagnosis.

Acoustic Speed Measurement Platform for Monitoring Highly Concentrated Gas Temperature Distribution

Acoustic thermography reconstructs 2-D gas temperature distributions by using sound speeds from multiple paths across a plane. However, a reliable platform that can provide accurate sound speeds in a highly concentrated temperature distribution environment has not been fully discussed. Most of the existing temperature reconstruction algorithms are developed using simulated data and validated with customized systems. The results from the reported systems are difficult to reproduce due to the lack of critical information, such as the methods for determining the time of flight (TOF). Moreover, previous attempts have not investigated the effect of a sharp temperature gradient, in which the difference of acoustic impedance between high- and low-temperature regions cannot be neglected. In response, this letter demonstrates a reliable acoustic platform designed specifically for measuring the acoustic speeds in an environment with a critical temperature distribution. The main components of the proposed platform are discussed in detail, including the TOF calculation technique, the hardware architecture, and the working principle. The performance of the platform has been evaluated by comparing the captured acoustic velocities and the reconstructed temperature map with results from a thermocouple array. The average acoustic velocity measured by the proposed platform for 100 times is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$341 \pm \ 3$</tex-math></inline-formula> m/s at room temperature (25 °C) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$354 \pm \ 5\ $</tex-math></inline-formula> m/s after heater turned <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> (38.27 °C). Moreover, the 2-D temperature map reconstructed by acquired acoustic velocities also matches the results from the thermocouple array. Therefore, the proposed platform can be considered as an accurate and reliable acoustic speed measurement system for monitoring the 2-D temperature distribution.

Line average wind speed measurement system of roadway cross-section based on ultrasonic transit time Difference

Aiming at the problems of low measurement accuracy, poor adaptability, and lack of real-time online measurement methods for roadway section average wind speed, combined with the characteristics of roadway section, based on the characteristics of time difference caused by ultrasonic propagation in forward and reverse flow medium, high-energy ultrasonic transmission and long-distance transit are realized by adopting automatic tracking correction technology of transmission frequency and high-pressure pulse drive technology. program-controlled filter amplification technology and peak hold technology are used to achieve high quality processing of received signals. Accurate measurement of ultrasonic transit time is realized by adopting AD high-speed sampling time positioning technology, floating threshold time difference measurement technology and circuit time delay self-determination measurement technology, and finally realizes the measurement of the average wind speed of the roadway cross-section line. The measurement system is tested on the gas flow standard device, and the measurement accuracy meets and exceeds the requirements of relevant standards. Compared with the current technical means for measuring cross-section wind speed in roadways, the system has the advantages of one-time measurement of average line wind speed, high accuracy, strong adaptability and real-time on-line monitoring.

Baseball Drag Measurements in Free Flight

While baseball is a popular sport with a storied history, the aerodynamic properties of the seamed sports ball are not fully understood. Reported aerodynamic baseball behaviors are primarily based on force measurements from wind tunnels. The following describes a methodology to measure baseball drag in free flight from changes in its speed. The method relies on a high accuracy ball delivery device and speed measurement system. It avoids the large infrastructure, stinger attachment and blockage effects associated with wind tunnels. In the present work, we examined the baseball drag as a function of orientation and with spin. The drag values retrieved from the proposed method are in good agreement with radar and video measurements. However, they are lower than those reported in other wind tunnel measurements, which was attributed to differences in the balls that were tested or the stinger attachment.

Influence of the Downwash Wind Field of Plant Protection UAV on Droplet Deposition Distribution Characteristics at Different Flight Heights

The aerial spraying of pesticides by plant protection unmanned aerial vehicles (UAV) is a process in which the spray droplet deposition on target sites occurs under the influence of the downwash wind field. The downwash wind field is the most important factor affecting droplet deposition distribution characteristics in an aerial spray. To understand the mechanism of the downwash wind field, spray tests were conducted at different flight heights by using a DJI UAV, and the downwash wind field in the three-dimensional direction (X-directional wind, Y-crosswind, and Z-vertical wind) was measured by using a wind speed measurement system for UAV. Combined with the droplet deposition of aerial spray, the distribution characteristics of the downwash wind field and the influence of the downwash wind field on droplet deposition were studied. The results showed that it had obvious differences in the distribution of the downwash wind field for UAV at different flight heights. As the flight height increases, the downwash wind field in X-direction and Z-direction showed a strong to weak trend, while the downwash wind field in Y-direction showed an opposite trend. In addition, it was found that the downwash wind field in Y-direction and Z-direction both have a significant influence on droplet deposition. With the increase of flight height, the change of the downwash wind field led to a gradual decrease in droplet deposition in the effective spray area, and droplets deposited more uniformly. For the DJI T16 plant protection UAV in this test, the optimal flight height was 2.0 m, and the downwash wind field had a better improvement effect on droplet deposition. Therefore, in order to make full use of the downwash wind field of UAV, the appropriate flight height should be selected to improve droplet deposition of liquid pesticide and achieve a better control effect for crop disease and pests when UAV is used for aerial spray operations in the field. This study revealed the influence mechanism of the downwash wind field on droplet deposition of aerial spray, and proposed appropriate operation parameters from the perspective of practical operation. It was expected to provide data support for improving the operation quality of aerial spraying and the formulation of field operation specifications.

Robust Vehicle Speed Measurement Based on Feature Information Fusion for Vehicle Multi-Characteristic Detection.

A robust vehicle speed measurement system based on feature information fusion for vehicle multi-characteristic detection is proposed in this paper. A vehicle multi-characteristic dataset is constructed. With this dataset, seven CNN-based modern object detection algorithms are trained for vehicle multi-characteristic detection. The FPN-based YOLOv4 is selected as the best vehicle multi-characteristic detection algorithm, which applies feature information fusion of different scales with both rich high-level semantic information and detailed low-level location information. The YOLOv4 algorithm is improved by combing with the attention mechanism, in which the residual module in YOLOv4 is replaced by the ECA channel attention module with cross channel interaction. An improved ECA-YOLOv4 object detection algorithm based on both feature information fusion and cross channel interaction is proposed, which improves the performance of YOLOv4 for vehicle multi-characteristic detection and reduces the model parameter size and FLOPs as well. A multi-characteristic fused speed measurement system based on license plate, logo, and light is designed accordingly. The system performance is verified by experiments. The experimental results show that the speed measurement error rate of the proposed system meets the requirement of the China national standard GB/T 21555-2007 in which the speed measurement error rate should be less than 6%. The proposed system can efficiently enhance the vehicle speed measurement accuracy and effectively improve the vehicle speed measurement robustness.

An Improved Stereo Matching Algorithm for Vehicle Speed Measurement System Based on Spatial and Temporal Image Fusion.

This paper proposes an improved stereo matching algorithm for vehicle speed measurement system based on spatial and temporal image fusion (STIF). Firstly, the matching point pairs in the license plate area with obviously abnormal distance to the camera are roughly removed according to the characteristic of license plate specification. Secondly, more mismatching point pairs are finely removed according to local neighborhood consistency constraint (LNCC). Thirdly, the optimum speed measurement point pairs are selected for successive stereo frame pairs by STIF of binocular stereo video, so that the 3D points corresponding to the matching point pairs for speed measurement in the successive stereo frame pairs are in the same position on the real vehicle, which can significantly improve the vehicle speed measurement accuracy. LNCC and STIF can be used not only for license plate, but also for vehicle logo, light, mirror etc. Experimental results demonstrate that the vehicle speed measurement system with the proposed LNCC+STIF stereo matching algorithm can significantly outperform the state-of-the-art system in accuracy.

Theoretical and experimental investigation on an integral time-delay feedback control combined with a closed-loop control for an infinitely variable transmission system

A nonlinear closed-loop speed ratio control combined with an integral time-delay feedback control is developed to adjust the speed ratio of an infinitely variable transmission (IVT) for a desired output speed with any variable input speed. The speed ratio control of the IVT system is developed based on its nonlinear dynamic model, which involves a forward speed controller and a crank length controller for varying operating conditions. The closed-loop forward speed controller can operate with efficient driving performance based on an optimal operation line of a prime mover. System identification is carried out to achieve high control performance of the IVT system. Comprehensive results of experimental investigation are presented to validate the proposed control strategy for the IVT system. An instrumented rotation speed measurement system is designed so that quantities necessary for the time-delay control variable can be measured. Experimental results show that the speed ratio of the IVT with the proposed control strategy can achieve an excellent tracking response for the desired constant output speed. This study reveals that fluctuations of the output speed of the IVT system can be reduced by time-delay feedback control.

Experimental Investigation on Control of an Infinitely Variable Transmission System for Tidal Current Energy Converters

High operation performance of a tidal current energy converter (TCEC) requires a gear transmission with a continuously variable speed ratio for low-speed and high-torque conditions. A nonlinear closed-loop control combined with an integral time-delay feedback control is developed to adjust the speed ratio of an infinitely variable transmission (IVT) system for TCECs. A speed ratio control for the IVT system involves a forward speed controller and a crank length controller for different tidal current speed ranges. The time-delay control is designed to reduce speed fluctuations of the output speed of the IVT with an accurate speed ratio. Experimental investigation was carried out to test the validity of the proposed control strategy for the IVT system. An instrumented rotation speed measurement system is designed so that quantities needed for the time-delay control variable can be measured. Experimental results show that the speed ratio of the IVT with the proposed control strategy can achieve an excellent tracking response for the desired constant output speed and reduce speed fluctuations of the output speed of the IVT by the time-delay feedback control.

A Low-Cost System for Measuring Wind Speed and Direction Using Thermopile Array and Artificial Neural Network

Recent developments in wind speed sensors have mainly focused on reducing the size and moving parts to increase reliability and stability. In this study, the development of a low-cost wind speed and direction measurement system is presented. A heat sink mounted on a self-regulating heater is used as means to interact with the wind changes and a thermopile array mounted atop of the heat sink is used to collect temperature data. The temperature data collected from the thermopile array are used to estimate corresponding wind speed and direction data using an artificial neural network. The multilayer artificial neural network is trained using 96 h data and tested on 72 h data collected in an outdoor setting. The performance of the proposed model is compared with linear regression and support vector machine. The test results verify that the proposed system can estimate wind speed and direction measurements with a high accuracy at different sampling intervals, and the artificial neural network can provide significantly a higher coefficient of determination than two other methods.

Novel laser Doppler tachometer

In order to improve the accuracy and universality of the rotational speed measurement, an instantaneous rotational speed measurement method based on laser Doppler technology is proposed. The composition and working principle of the new system are discussed in detail. Theoretical and experimental results show that the new rotational speed measurement system belongs to the non-contact method, which eliminates the quantization error of the contact method and greatly improves the applicability and accuracy. Compared to the commonly used method, the measurement accuracy of the new rotational speed measurement system will not be affected by the system’s installation angle deviation, and it does not need to measure the radius of the rotating body, so the influence of the radius fluctuation of the rotating body on the measurement accuracy can be avoided while outputting the rotational speed in real time. The relative error of the rotational speed measurement is less than 0.06% (1σ).

Research of speed measurement and prediction system for railway train based on single chip microcomputer

The main content of this research is how to know the speed, location and arrival time of the rail train, and provide the information for passengers to take the rail train. Because urban rail transit is built in the underground environment, there will be some limitations in the selection of speed measurement and positioning methods for rail trains. This research is based on the actual situation, using the hardware system based on the single chip microcomputer as the vehicle equipment, real-time speed measurement, positioning and prediction of the rail train. Provide effective data information for train operation, dispatching and passengers’ taking.

Design and implementation of a speed test system for campus network based on IPv6

In order to realize the end-to-end network speed measurement in the campus network and solve the problem that the current speed measurement system is not well adapted for IPv6 campus network, we adopt the C/S mode to build a software for the client/server ends distributed in the selective target area. For end-to-end testing, the software provides various methods of network speed measurement including FTP download, and provides current network speed measurement data. We also design network quality classification standards, and evaluate current network conditions according to them. At the same time, our software can do the speed measurement for localized download service of high-quality resources.

A 1GHz Low-cost, Ultra Low-noise Preamplifier

A high quality, compact 1GHz preamplifier suitable for operation in conjunction with micro channelplates (MCP) and silicon Photomultipliers (SiPM), that is comprised of two integrated circuits is described inthis paper. The amplifier requires no adjustment and has a flat response from low frequencies and adequatebandwidth for high speed measurement systems.

A High Accuracy and High Speed Imaging and Measurement System for Rail Corrugation Inspection

In order to decrease the noise and vibration of operation in railway tracks, it is necessary to inspect the status of them frequently. A main task in inspection of railway tracks is measurement of rail corrugation. The rail corrugation occurs during operation due to wear. The dynamic component of the vertical wheel-rail contact force, as induced by rail corrugation is an important source to vibration. Also, according to the corrugation wavelength and railway vehicle speed, a dynamic excitation is generated which is an important source to noise. It is essential to utilize a system to check the rail corrugation. In this article, a new measurement system based on image processing is proposed to perform the corrugation measurement in a reliable manner, while traditional measurement systems are based on acceleration measurement or chord measurement and they are not reliable due to physical contact or need for knowing the characteristics of the track. The proposed system is based on laser triangulation principle using image processing to measure the rail corrugation precisely and quickly. This approach is an efficient technique for high-speed and high-accurate rail corrugation measurement. Experimental results show the capability of the system for practical usages.

A Rotation-Speed Measurement System Based on Magneto-Inductive Effect

There are few reports on high rotational speed measurement of brushless direct current (DC) motors based on giant magneto-inductive effect. In this study, a rotational speed measurement system based on giant magneto-inductive effect is established for measuring the rotational speeds of DC motors. Successive sawtooth waves are found when rotating shaft is close to the GMI sensor. Through using the magneto-inductive sensing system, different high rotational speeds (1500∼24000 r/min) of the motor are accurately measured. Therefore, this giant magneto-inductive sensor may be used for high rotational speed measurement of motors.

Gerçek Zamanlı Araç Hız Ölçümü ve Takip Sistemi Tasarımı

Öncelikli amacı araçların konumunu takip etmek olan araç takip sistemlerinin teknolojik gelişmelere bağlı olarak son yıllarda birçok alanda kullanıldıkları görülmektedir. Gerçek zamanlı araç takibi ile araçların güvenliği, toplu taşıma sistemlerinin izlenmesi, filoların yönetimi gibi birçok uygulama gerçekleştirilmektedir. Ayrıca, küresel boyutta yollardaki araç sayısı da hızla artmaktadır. Bu nedenle, Global Konumlandırma Sistemini (GPS) ve Mobil İletişim için Global Sistem (GSM) kullanarak araçların takip sistemlerinin geliştirilmesi ile araçların konumlarına kolay bir şekilde ulaşılabilmektedir. Bu çalışmada, GSM/GPRS ve GPS teknolojileri yardımıyla kullanışlı bir araç takip ve hız ölçüm sistemi önerilmiştir. Önerilen sistemde, öncelikle tasarlanan devre üzerinde GPS ile aracın konum bilgisi alınarak GSM modülü üzerinden bir web sunucusuna aktarılmaktadır. Sonraki aşamada, web sunucusuna gelen bilgiler bağlı bir web servis aracılığıyla, web ve mobil uygulamalara aktarılarak, aracın konumu harita üzerinde izlenebilmektedir. Ayrıca, sistemde belirli aralıklarla alınan konum bilgileri arasındaki mesafe ve zaman parametreleri kullanılarak, aracın hız bilgisi de gerçek zamanlı belirlenebilmektedir. Yürütülen test işlemlerinde, hareket halindeki bir araç içerisinde gerçek zamanlı olarak gerçekleştirilen 8 farklı hız değerinin ölçüm sonucu karşılaştırmasına göre, önerilen sistem ile ölçülen iki hız değerinin arasında mutlak ortalama hata 1.51 km/s olarak hesaplanmıştır. Ek olarak, önerilen sistem ile aracın tam konum bilgisi belirlendikten sonra, kullanıcı SMS ile bilgilendirilebilmektedir. Sonuç olarak, geliştirilen gerçek zamanlı araç takip sistemi özellik, işlevsellik ve maliyet bakımından mevcut çözümlerle karşılaştırıldığında daha avantajlı bir altyapı sunmaktadır.

On the Calibration of GNSS-Based Vehicle Speed Meters†.

Thanks to their metrological characteristics (accuracy, dimensions, synchronization capability, easy interfacing, and so on), in the last few years, the GNSS (Global Navigation Satellite System) based speed instruments are often used in a wide field of application. The traceability of the measurement results achieved by the GNSS instrument should be made by means of calibration procedures in compliance with the ISO/IEC 17025 standard and ILAC (International Laboratory Accreditation Cooperation) policy on the traceability of measurement results. In this context, some calibration methodologies have been proposed in the literature or used by some calibration centers. In a speed range from 1 to 300 km/h, an analysis on the suitability of the experimental calibration method (based on a couple of photocells placed on the road at a certain distance) for the GNSS speed measurement systems is presented in this paper. An analysis of the measurement setup has allowed for the recognition of both all the uncertainty contributions and defines the variability range of their values. After the formulation of the relationships between the uncertainty contributions and the total calibration uncertainty due to the calibration method, the sensitivity analysis has been made. The analyzed measurement setup, even if considering a careful choice of both instrumentations and methodologies, is suitable for the calibration of high accuracy GNSS based instruments only considering distances between the photocells sufficiently large and for speed values lower than 200 km/h. In any case, the proposed analysis can be a useful tool to allow for the choices on the measurement setup to reach the desired trade-off between calibration costs and compliance with technical requirements and also the calibration of instrumentation different by GNSS.

Analytical Modeling for a Video-Based Vehicle Speed Measurement Framework.

Traffic analyses, particularly speed measurements, are highly valuable in terms of road safety and traffic management. In this paper, an analytical model is presented to measure the speed of a moving vehicle using an off-the-shelf video camera. The method utilizes the temporal sampling rate of the camera and several intrusion lines in order to estimate the probability density function (PDF) of a vehicle’s speed. The proposed model provides not only an accurate estimate of the speed, but also the possibility of being able to study the performance boundaries with respect to the camera frame rate as well as the placement and number of intrusion lines in advance. This analytical model is verified by comparing its PDF outputs with the results obtained via a simulation of the corresponding movements. In addition, as a proof-of-concept, the proposed model is implemented for a video-based vehicle speed measurement system. The experimental results demonstrate the model’s capability in terms of taking accurate measurements of the speed via a consideration of the temporal sampling rate and lowering the deviation by utilizing more intrusion lines. The analytical model is highly versatile and can be used as the core of various video-based speed measurement systems in transportation and surveillance applications.