Development and Application of a Vision-Based System for Structural Monitoring of Railway Catenary System
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With the continuous increase of train speed and the expansion of the railway network, health monitoring and predictive maintenance of railway infrastructure are becoming increasingly important. The increasing investments in inspection and infrastructure maintenance have initiated the need for intelligent and accurate measuring techniques. Railway catenary systems are critical to ensure a stable and continuous power supply for electrical railways. The current collection is achieved as the contact wire directly interacts with the pantograph, installed on the car-body roof to provide an electrical current to the engine. The dynamic behaviour of catenary systems is significant to determine the current collection quality. This thesis proposes a vision-based line-tracking system (VIBLITE) to enable remote, non-contact and non-marker uplift measurements of catenary systems. This system avoids the defects of the traditional uplift measuring methods, e.g., track access, substantial time and work for sensor or marker installation on wires. An image-processing line-tracking algorithm for addressing the essential challenge of tracking slender wires without markers against noisy backgrounds is developed to achieve robust and accurate uplift measurements. The accuracy, robustness and applicability of VIBLITE are validated and demonstrated through numerical experiments, the field uplift measurement of the railway catenary system and the identification of the contact wire in a diverse city environment. Damping plays an essential role in numerical simulations of pantograph-catenary interaction, especially for multiple pantographs. However, damping estimation of existing catenary sections is recognised as a challenge, and only a few studies have been published with single values of damping estimations. Thus, the spatially distributed damping of an existing catenary span was estimated by VIBLITE through uplift measurements. The damping ratios were identified using the covariance-driven stochastic subspace identification (Cov-SSI) method. The results were presented as Rayleigh damping coefficients, showing a notable spatial variation to be used in numerical simulations. A small but clear train direction dependency of the damping distribution was observed over the entire span. Thus, it is recommended to consider the spatial damping distribution's influence when conducting future numerical simulations, especially when energy dissipation can be a vital component. Finally, catenary section overlaps are designed to provide a transition between two consecutive catenary sections. The thesis studied the pantograph-catenary interaction and transition at the overlap span experimentally. VIBLITE with a new measuring method for the specific overlap span was developed and implemented under regular train operations to estimate the dynamic spatial vibration of the contact wires. The research explores the reasons for the high contact forces and the contact loss rendering arcing at overlap span. The important transition section distance, i.e., the length where the pantograph runs on both contact wires, was obtained and assessed at varying train speeds to study correlations.