A Vehicle-Borne Mobile Mapping System Based Framework for Semantic Segmentation and Modeling on Overhead Catenary System Using Deep Learning

Overhead catenary system (OCS) automatic detection is of important significance for the safe operation and maintenance of electrified railways. The vehicle-borne mobile mapping system (VMMS) may significantly improve the data acquisition. This paper proposes a VMMS-based framework to realize the automatic detection and modelling of OCS. The proposed framework performed semantic segmentation, model reconstruction and geometric parameters detection based on LiDAR point cloud using VMMS. Firstly, an enhanced VMMS is designed for accurate data generation. Secondly, an automatic searching method based on a two-level stereo frame is designed to filter the irrelevant non-OCS point cloud. Then, a deep learning network based on multi-scale feature fusion and an attention mechanism (MFF_A) is trained for semantic segmentation on a catenary facility. Finally, the 3D modelling is performed based on the OCS segmentation result, and geometric parameters are then extracted. The experimental case study was conducted on a 100 km high-speed railway in Guangxi, China. The experimental results show that the proposed framework has a better accuracy of 96.37%, outperforming other state-of-art methods for segmentation. Compared with traditional manual laser measurement, the proposed framework can achieve a trustable accuracy within 10 mm for OCS geometric parameter detection.

Development of requirements for logic controls of the speed lines catenary system maintenance

Objective: To develop requirements for the organization of maintenance of the catenary system based on the actual state indicated by the digital diagnostic and monitoring platform in the logic control system for high-speed traffic. Methods: An overview analysis of high-speed catenary system diagnostics and monitoring systems is applied. Results: The systems of monitoring and automated control of catenary system devices in high-speed lines have been studied. The analytical findings as regards the maintenance methods according to the preventive maintenance schedule and based on the actual state monitoring data have been presented. Requirements for diagnostic and monitoring devices 15 of the high-speed lines catenary system have been formulated, aimed at improving the quality attributes of current collection. Practical importance: A structural diagram of quality diagnostics and monitoring for the current collection in the high-speed Current Collector–Catenary system was obtained. The design concept of a prin-cipal model of logic control of the catenary system life cycle has been developed

Spatial-Prior-Guided Attention for Small Object Detection in Overhead Catenary System

The small defects in overhead catenary system (OCS) can result in long time delays, economic loss and even passenger injury. However, OCS images exhibit great variations with complex background and oblique views which pose a great challenge for small defects detection in high-speed rail system. In this paper, we propose the spatial-prior-guided attention for small object detection in OCS with two main advantages: (1) The spatial-prior is proposed to retain the spatial information between small defects and the electric components in OCS. (2) Based on spatial-prior, the spatial-prior-guided attention model (SAM) is designed to highlight useful information in the features and suppress redundant features response. SAM can model the spatial relations progressively and can be integrated with state-of-the-art feed-forward network architecture with end-to-end training fashion. We conduct extensive experiments on both Split pin datasets and PASCAL–VOC datasets and achieve 97.2% and 79.5% mAP values, respectively. All the experiments demonstrate the competitive performance of our method.

Crosswind Effects on Interaction Performance of High-speed Railway Pantograph-catenary System: A Case Study in Chengdu-Chongqing Passenger Special Railway

As a common disturbance to the railway pantograph-catenary system, the crosswind may deteriorate the current collection quality and threat operational safety. The main topic of this paper is to study the effect of crosswind on the interaction performance of pantograph-catenary considering the aerodynamic forces acting on both the pantograph and catenary. The pantograph-catenary system of the Chengdu-Chongqing passenger special railway is adopted as the analysis object. The absolute nodal coordinate formulation (ANCF) is employed to build the catenary model, of which the numerical accuracy is validated via the comparison with the field measurement data collected from an inspection vehicle operating at 378 km/h. A special spatial grid is defined for the pantograph-catenary system to generate the stochastic wind field based on the empirical spectrum. According to the quasi-steady theory, the wind load acting on the catenary is derived. Computational fluid dynamics (CFD) is employed to calculate the lift and drag forces acting on each component of the pantograph, which are used to derive the equivalent aerodynamic force that can be applied in the lumped-mass model. The simulation results indicate that the pantograph-catenary system of Chengdu-Chongqing passenger special railway has an acceptable performance with a crosswind speed of 20 m/s. But when the crosswind increases up to 30 m/s, some contact force statistics exceed the safety threshold with a turbulence intensity of more than 17%. Through the analysis of the operational safety, it is found that the contact wire always works within the safety range of the pantograph head with a crosswind speed of 30 m/s. But some safety issues can be seen from the maximum uplift of the pantograph head with a turbulence intensity of more than 21%.

Effect of friction on transverse vibration of string under moving load

Many engineering applications involve exerting moving harmonic load on a string like structure. Usually the interface between these structures and the moving load has some friction. A common example is a pantograph catenary system, which is used in locomotives for power collection. The aim of this paper is to develop a mathematical model of a simplified system consisting of infinitely long axially tensioned continuum and a moving harmonic load with friction acting at the interface. Equation of motion has been derived by resolving forces at that point. Subsequently the basic characteristics of the system are obtained by solving the model numerically. It is observed that the effect of friction obtained is negligibly low higher value of axial tension, but can significantly increase the string response at a particular range of coefficient of friction value when the axial tension is low.

Effect of Train Energy Consumption on the Wear of Railroad Catenary Contact Conductor

With current rise of climate change worldwide, transport industry contributes up to 21% of the world’s total Green House Gases (GHG). In addition to that developing cities are facing great changes in urbanization, population growth and environmental concerns. In these instances, railway transportation is a top contender on land transport mode to achieve sustainable mobility in fast growing cities. For railway operation, apart from wheel-rail contact, the catenary system has a very high initial investment cost as well as associated maintenance cost. It is important to monitor the damage evolution of the catenary components for developing better maintenance strategies. This study utilizes a co-simulation between the railway catenary system dynamics and electrical power flow. With reference to Addis Ababa Light Rail Transit Service (AALRTS), the power and current drawn by the running train were calculated. Then the heat losses in the conductor wire were obtained with respect to train location on the line. This procedure was followed by thermal analysis that allowed us to obtain temperature rise in the conductor. The temperature results were used as some of the inputs in the dynamic explicit finite element model of the coupled catenary and sliding pantograph. From the finite element analysis, different quantities such as contact forces and pressures, temperature rise because of friction between sliding parts, and deflections of conductor were obtained. Furthermore, the fluctuations of train loads were taken into consideration in the calculation of power consumption and hence in temperature rise. Increase in loads resulted in increase of current drawn which increases the temperature of the mating parts, which in-turn affected frictional stresses and forces. The latter were the input parameters in Archard wear model for calculating wear volume from the catenary contact conductor. It was observed that at different scenarios of train passenger loadings, the train experiences an increase in energy consumption, which results in slight increase of contact conductor wear by material removal.