Condition monitoring systems are commonly exploited to assess the health status of equipment. A fundamental part of any condition monitoring system is data acquisition. Meaningfully estimating the current condition and predicting the future behaviour of the equipment strongly depend on the characteristic of the data measurement stage. Nowadays, condition monitoring has wide applications in the railway industry, and various monitoring approaches have been proposed for the inspection of wheel and rail conditions. In-service condition monitoring of wheels provides the real-time data required for maintenance planning, while in-workshop inspection is normally done at fixed intervals carried out periodically. In-service data acquisition can be divided into on-board and wayside measurements. In this paper, on the basis of these classifications, the existing data acquisition techniques for the monitoring of railway wheel condition are reviewed, and the state-of-the-art methods and required research are discussed.

/pdf/condition-monitoring-approaches-for-the-detection-of-railway-3dk2o1pvnm.pdf

Condition monitoring approaches for the detection of railway wheel defects

Railway vehicles have become a modern transport media day by day. With the development of high-speed trains, this transportation way has been widely used for the transportation of people and cargo. However, several fault type in the pantograph-catenary system affects the performance of the train. Contact between a pantograph and catenary must slide along train movement. A sufficient lifting force should be applied to the contact wire when train moves. Vibrations occurred between a pantograph and catenary system and oscillations of contact wire cause the loss of contact. So, burst of arcing occurs in contact point. In this study, a new computer vision based method is proposed to control the contact force. The proposed algorithm utilizes the edge detection and Hough transform for detection of pantograph height. The obtained height is given to the control algorithm and the height of the pantograph is adjusted. The proposed method is verified by using a video taken from real pantograph and efficient results has been obtained.

A new computer vision approach for active pantograph control

Distributed dynamic fiber optic sensors have the potential to measure the strain increase along a rail when it is loaded. This study investigated the use of fiber optic sensors to measure distributed dynamic strains during the passage of rail traffic. The experimental program included both a laboratory evaluation and a field trial. In the laboratory experiments, two methods of affixing the fiber to the rail are compared (minimal and optimal surface preparation) in order to determine whether rapid field installation is possible. Furthermore, displacement measurements from linear potentiometers and Digital Image Correlation are used to illustrate and evaluate the calculation of rail displacement from rail strains. Finally, the distributed strain measurement technique was used to measure rail strains at a level-crossing using vehicular loading under low vibration conditions (hi-rail vehicle) and high vibration conditions (in-service passenger train) to investigate the range of applicability of the current state of this technology under field conditions.

Measurement of distributed dynamic rail strains using a Rayleigh backscatter based fiber optic sensor: Lab and field evaluation

The influence of contact surface upon the dynamic performance of a pantograph–catenary system is a question that has been highlighted by the increasing use of high speed railways. Using the mode-su...

Dynamic performance of a pantograph–catenary system with consideration of the contact surface:

Wheel flats are a key fault in railway systems, which can bring great harm to vehicle operation safety. At present, most wheel flat detection methods use qualitative detection and do not meet practical demands. In this paper, we used a railway wheel flat measurement method based on a parallelogram mechanism to detect wheel flats dynamically and quantitatively. Based on our experiments, we found that system performance was influenced by the train speed. When the train speed was higher than a certain threshold, the wheel impact force would cause vibration of the measuring mechanism and affect the detection accuracy. Since the measuring system was installed at the on-site entrance of the train garage, to meet the speed requirement, a three-dimensional simulation model was established, which was based on the rigid-flexible coupled multibody dynamics theory. The speed threshold of the measuring mechanism increased by the reasonable selection of the damping coefficients of the hydraulic damper, the measuring positions, and the downward displacements of the measuring ruler. Finally, we applied the selected model parameters to the parallelogram mechanism, where field measurements showed that the experimental results were consistent with the simulation results.

Railway Wheel Flat Detection System Based on a Parallelogram Mechanism

As one of the most important transportation, the safety of railway is paid much attention to. The quality of wheel should
be checked periodically, especially in high-speed application. Normally, Non Destructive Testing (NDT), such as
ultrasonic inspection method, is applied on wheels to find the defect. A stationary automatic railway wheelset inspection
system by using ultrasonic technique is described in this paper. The phased array ultrasonic technique and wheel defect
inspection method is described in detail. Specially designed line is installed for wheelset transportation. Wheelset lifting
and rotating device is used for wheelset loading, unloading and rotating. A steel frame with complicated mechanical
structure and ultrasonic devices are designed for wheelset defect detecting. System ultrasonic performance, system
working flow, system control networking, data processing and results displaying are also described in the paper. Now,
the system is installed in Chinese EMU maintenance center for disassembled wheelset inspection and the safety of
wheels is well protected.

Automatic railway wheelset inspection system by using ultrasonic technique

In three dimensional detection of the rail shape by Fourier Transform profilometry (FTP), filtering is one of the key links before Fourier transform. The choice of filtering window decides the spectrum overlapping degree of deformed fringes, so as to decide the measurement precision of the rail shape. In this paper, based on wavelet ridge theory the size of the filter window is self-adaptive according to the frequency alternation of deformed fringes. And thus the optimum matching window size is decided, the frequency overlapping is furthest reduced and the measurement precision is improved. Simulation and experiments manifest that self-adaptive filtering can greatly enhance the precision in three dimensional detection, which offers a new thinking and method in rail shape recovery and defect detection.

Three dimensional detection of rail shape based on self-adaptive filtering

Pantograph sliding plate is the most important electricity-collecting part in locomotive power supply system. Once the
sliding plates are disabled, they will be severe dangerous for safety. The measurement for pantograph of 27.5KV is
especially difficult. The article uses non-contact and online dynamic detection by utilizing CCD technique to solve the
problem. The system will get all images of sliding plates after triggering by space arrangement of CCD cameras
cooperated with flashlights. The precision of demarcate is guaranteed by special methods. It adopts directional edge
search to get sliding plates, and connect the images of different CCDS. It also makes use of conditional Hough
transformation to locate the wire. The wear on sliding plates will be given after complicated processing. The system is
applicable to the detection for all kinds of pantographs by adding different arithmetic amends. At last the precision can
achieve ±0.5mm . At the same time a database is setup which can give the trend curve of wear, it can predict the limit
time of the sliding plates.

Application of CCD measurement technique for wear on pantograph sliding plates

This paper describes a multi-FPGA imaging system dedicated for the real-time imaging using the Total Focusing Method (TFM) and Full Matrix Capture (FMC) The system was entirely described using Verilog HDL language and implemented on Altera Stratix IV GX FPGA development board The whole algorithm process is to: establish a coordinate system of image and divide it into grids; calculate the complete acoustic distance of array element between transmitting array element and receiving array element, and transform it into index value; then index the sound pressure values from ROM and superimpose sound pressure values to get pixel value of one focus point; and calculate the pixel values of all focus points to get the final imaging The imaging result shows that this algorithm has high SNR of defect imaging And FPGA with parallel processing capability can provide high speed performance, so this system can provide the imaging interface, with complete function and good performance

Implementation of total focusing method for phased array ultrasonic imaging on FPGA

As the key critical load-bearing parts of the high-speed EMU, the quality of wheel set has diiect impact on the safety. Now in China, equipment for detecting the wheels quality is usually installed in the CRH entrance line with CRH passing in low speed. As one of the important contents of wheel quality detection, whether wheel flat can be timely and accurate detected or not, is especially important. Although there are lots of methods for wheel flat detection in low speed, each one has its advantages and disadvantages. This paper introduces the contact method which is widely used in China as the quantitive detection for CRH wheel. But there is a key disadvantage which makes this equipment fails in some condition. To solve the problem, a new method is raised, which uses the wheel flat detection lever installed outer the rail and combines the advantages of the inner and outer. The new method makes this application in real function and will have a great reference value.

Quanke Zhao

Papers

Automatic railway wheelset inspection system by using ultrasonic technique

Three dimensional detection of rail shape based on self-adaptive filtering

Application of CCD measurement technique for wear on pantograph sliding plates

Implementation of total focusing method for phased array ultrasonic imaging on FPGA

Research on the detecting method of CRH wheel flat at low speed