Local track irregularity identification based on multi-sensor time-frequency features of high-speed railway bridge accelerations

Shortwave track diseases are generally reflected in the form of local track irregularity. Such diseases will greatly impact the train-track-bridge interaction (TTBI) dynamic system, seriously affecting train safety. Therefore, a method is proposed to detect and localize local track irregularities based on multis-sensor time-frequency features of high-speed railway bridge accelerations. Continuous wavelet transform (CWT) is used to analyze the multi-sensor accelerations of railway bridges. Moreover, time-frequency features based on the sum of wavelet coefficients are proposed, considering the influence of the distance from the measurement points to the local irregularity on the recognition accuracy. Then, the multi-domain features are utilized to recognize deteriorated railway locations. A simply-supported high-speed railway bridge traversed by a railway train is adopted as a numerical simulation. Comparative studies are conducted to investigate the influence of vehicle speeds and the location of local track irregularity on the algorithm. Numerical simulation results show that the proposed algorithm can detect and locate local track irregularity accurately and is robust to vehicle speeds

Adaptive noise cancelling and time–frequency techniques for rail surface defect detection

Adaptive noise cancelling (ANC) is a technique which is very effective to remove additive noises from the contaminated signals. It has been widely used in the fields of telecommunication, radar and sonar signal processing. However it was seldom used for the surveillance and diagnosis of mechanical systems before late of 1990s. As a promising technique it has gradually been exploited for the purpose of condition monitoring and fault diagnosis. Time-frequency analysis is another useful tool for condition monitoring and fault diagnosis purpose as time-frequency analysis can keep both time and frequency information simultaneously. This paper presents an ANC and time-frequency application for railway wheel flat and rail surface defect detection. The experimental results from a scaled roller test rig show that this approach can significantly reduce unwanted interferences and extract the weak signals from strong background noises. The combination of ANC and time-frequency analysis may provide us one of useful tools for condition monitoring and fault diagnosis of railway vehicles

On-line monitoring of vertical long wavelength track irregularities using bogie pitch rate

Long wavelength track irregularities are the key factors which influence vehicle stability and comfort. An on-line monitoring method is proposed to detect the vertical long wavelength track irregularities based on bogie pitch rate. Firstly, the principle of on-line monitoring method based on axle-box acceleration or bogie pitch rate was presented. Secondly, to process bogie pitch rate, a mix-filtering approach which contains time-space domain transformation, double integration, baseline correction and RLS (Recursive Least Squares) adaptive compensation filter was proposed. Thirdly, a coupling dynamics model of vertical vehicle-track interactions was developed to obtain bogie pitch rate. The obtained bogie pitch rate was then filtered with the signal processing approach. When the processed result compares with the actual irregularities, the SD (Standard Deviation) is 0.327 mm and the NMSE (Normalized Mean Square Error) is –9.1495. The experimental result shows that the proposed on-line monitoring method based on bogie pitch rate and signal processing approach are capable of monitoring the long wavelength track irregularities accurately and effectively

Acceleration-based condition monitoring of track longitudinal level using multiple regression models

In this paper, a condition monitoring system for railway track geometry is presented. The methodology has been designed for high-speed application, where the train travels at the maximum allowed speed for most of the trip. The system is designed to rely on acceleration data recorded by in-service vehicles to provide estimations of the track longitudinal level, based on pre-built regression models. It exploits synthetic indicators sampled over predefined track sections 100 m long. Different predictors are considered, computed both from acceleration data and from track geometry measured by the diagnostic train. The proposed modelling strategy allows distinguishing between isolated and distributed defects that populate the railway track as well as reproducing the evolution over time of the maximum longitudinal level registered in the considered track section; moreover, also accurate predictions of the defect amplitude are made. The results have been validated against track geometry data recorded by the diagnostic train during a monitoring period of 2 years. It is proven that the proposed system could support current maintenance strategies, providing a continuous flow of data to monitor the track infrastructure

Experimental Investigation on Condition Monitoring Opportunities of Tramway Tracks

The increasing demands for guided transportation modes in urban areas generate the need of high-frequency services. Due to the frequent services, the track deterioration process will be accelerated. Therefore, the exact knowledge of track quality is highly important for every railway company to provide high quality service level.For monitoring of tramway tracks, an unconventional vehicle dynamics measurement setup is developed, which records the data of 3-axes wireless accelerometers mounted on wheel discs of regular in-service tram. In the implementation of prototype system, the bogie side-frame and car body mounted sensors are also fitted to the instrumented vehicle to compare the efficiency of these conventional solutions with the developed arrangement. At the first test period, the instrumented vehicle works as a dedicated inspection vehicle, in order to keep the constant velocity and help to determine the influencing factors on results. Accelerations are processed to obtain the track irregularities, in order to determine whether the track needs to be repaired. Real data come from measurements taken on tram line 49 of the Budapest (Hungary) and they have been validated by comparing results to the actual state of the track provided by a track geometry monitoring trolley and visual inspection. This paper presents the developed methods used for validation and the analysis of preliminary results of the wheel discs mounted accelerometers. This vehicle dynamic measurement system is cheap to implement and no significant modification of the vehicle is required. Therefore, in-service vehicles equipped with this system may serve a good opportunity for monitoring tramway track, while it multiple passes over same track section

On-line monitoring of vertical long wavelength track irregularities using bogie pitch rate

Long wavelength track irregularities are the key factors which influence vehicle stability and comfort. An on-line monitoring method is proposed to detect the vertical long wavelength track irregularities based on bogie pitch rate. Firstly, the principle of on-line monitoring method based on axle-box acceleration or bogie pitch rate was presented. Secondly, to process bogie pitch rate, a mix-filtering approach which contains time-space domain transformation, double integration, baseline correction and RLS (Recursive Least Squares) adaptive compensation filter was proposed. Thirdly, a coupling dynamics model of vertical vehicle-track interactions was developed to obtain bogie pitch rate. The obtained bogie pitch rate was then filtered with the signal processing approach. When the processed result compares with the actual irregularities, the SD (Standard Deviation) is 0.327 mm and the NMSE (Normalized Mean Square Error) is –9.1495. The experimental result shows that the proposed on-line monitoring method based on bogie pitch rate and signal processing approach are capable of monitoring the long wavelength track irregularities accurately and effectively

Measurement of Railway Track Geometry: A State-of-the-Art Review

The worldwide increase in frequency of traffic for passenger trains and the rise of freight trains over the recent years necessitate the more intense deployment of track monitoring and rail inspection procedures. The wheel-rail contact forces, induced by the static axle loads of the vehicle and the dynamic effects of ground-borne vibration coming from the track superstructure, have been a significant factor contributing to the degradation of the railway track system. Measurements of track irregularities have been applied since the early days of railway engineering to reveal the current condition and quality of railway lines. Track geometry is a term used to collectively refer to the measurable parameters including the faults of railway tracks and rails. This paper is aiming to review the characteristics of compact inertial measurement systems (IMUs), their components, installation, the basic measures of the quality of the track using motion sensors, like accelerometers, gyroscopes and other sensing devices mounted on different places of the vehicle. Additionally, the paper briefly discusses the fundamentals of inertial navigation, the kinematics of the translational and rotational train motions to obtain orientation, velocity and position information

Metodología para la mejora del diseño de sistemas mecánicos de responsabilidad para el uso de tecnologías avanzadas de mantenimiento DM&M

Mención Internacional en el título de doctorEl ferrocarril es uno de los medios de transporte más utilizados y seguros en la actualidad, jugando un papel muy importante en la movilidad de las personas entre territorios. Además, en los últimos años está experimentando un crecimiento significativo, impulsado por la Alta Velocidad, con trenes capaces de superar los 300 km/h que reducen ostensiblemente la duración de viajes en trayectos de largo recorrido. El mantenimiento del parque ferroviario en un estado de funcionamiento óptimo es prioritario para la operatividad y la seguridad de los servicios. Esto requiere un conocimiento del estado de la vía y de los vehículos ferroviarios, lo cual suele hacerse vía técnicas de auscultación y análisis de parámetros vibratorios. En la presente Tesis Doctoral se ha desarrollado una metodología original encaminada al establecimiento de un procedimiento de diagnóstico del estado de los elementos mecánicos de un sistema ferroviario de alta velocidad mediante el análisis de vibraciones. Esta metodología engloba todos los procesos necesarios para realizar la diagnosis del estado operativo: definición del sistema mecánico analizado, establecimiento de las condiciones de medida, definición del sistema de medida y del sistema de adquisición y registro de datos, acceso y gestión de la base de datos de vibración, selección y consolidación de los datos, tratamiento de los datos mediante técnicas de análisis de señal, en el dominio del tiempo, de la frecuencia y del tiempo-frecuencia y selección de indicadores del estado operativo del sistema. La metodología se aplica a un Tren de Alta Velocidad durante su operación comercial, registrando medidas de las señales de vibración en diferentes condiciones de velocidad, trayecto, tramo y estado operativo. Las medidas vibratorias se han analizado utilizando diversas técnicas de tratamiento de señales en los dominios del tiempo, de la frecuencia y del tiempofrecuencia, algunas tomadas de la literatura técnica y otras originales, desarrolladas expresamente para esta investigación. La interpretación de los resultados obtenidos ha permitido la selección de indicadores del estado operativo del vehículo ferroviario. Para facilitar las tareas de selección y análisis de los datos de vibraciones, se ha concebido una herramienta informática que implementa todas las técnicas de tratamiento de la señal utilizadas. La aplicación software desarrollada dispone de una interfaz gráfica que permite acotar las señales vibratorias a procesar y acceder a todas las técnicas de análisis. Además, permite generar automáticamente informes de los resultados gráficos obtenidos e ir generando un histórico de resultados. Tanto la metodología propuesta como la herramienta software desarrollada tienen un carácter generalista, serían aplicables a cualquier otro sistema mecánico de similares características.Railway is one of the most used and safest modes of transportation today, playing a key role in the mobility of people between territories. In addition, it is undergoing a significant growth driven by High Speed Rail in recent years. High Speed Trains are able to exceed 300 km/h and reduce significantly the duration of travel on long journeys. The maintenance of rolling stock in a good working order is a priority for the operation and safety of the commercial services. This requires the knowledge of the condition of the track and the rail vehicles, which is usually done via auscultation techniques and analysis of vibratory parameters. In this Doctoral Thesis, it has been developed an original methodology aimed at the development of a procedure for diagnosing the state of the mechanical elements of a high-speed rail system through the analysis of vibrations. This methodology encompasses all the processes necessary to perform the operating state diagnosis: definition of the analysed mechanical system, definition of measurement conditions, definition of the measurement system and of the data acquisition and registration system, access and management of the vibration data database, selection and consolidation of data, data processing through signal analysis techniques, in time, frequency and time-frequency domains, and selection of indicators of the operating state of the system. The methodology is applied to a High Speed Train in commercial operation, recording the measurements of the vibration signals in different conditions of speed, path, section and operating state. Vibratory measurements have been analysed using different signal processing techniques in time, frequency and time-frequency domains; some techniques have been taken from the literature and other are original techniques, developed specifically for this research. The interpretation of the obtained results has led to the selection of indicators of the operating state of the railway vehicle. To facilitate the tasks of selection and analysis of vibration data, it has been designed a computer tool that implements all the used signal processing techniques. The developed application software has a graphical interface that allows to set the vibratory signals to process and to access to all the analysis techniques. In addition, it allows to automatically generate reports of the graphic results and to create a history of results. Both the proposed methodology and the developed software tool have a general nature, they would be applicable to any other mechanical system of similar characteristics.Programa Oficial de Doctorado en Ingeniería Mecánica y de Organización IndustrialPresidente: María Luisa Martínez Muneta.- Secretario: Gerardo Peláez Lourido.- Vocal: María Tomás Rodrígue