Study of an onboard wired-wireless health monitoring system equipped with power save algorithm for freight railway wagons

Goods transport is an essential factor for the European market for its significant contribution to economic growth and thus to the creation of new employment. Nowadays, approximately 75% of goods are transported by road within the European Union. The use of more efficient and sustainable modes of transportation, such as rail transport and inland waterways, would reduce oil imports and pollution abatement. The growth of rail goods transport must be accompanied by an increasing introduction of tools and technologies that make possible to constantly monitor the European rolling stock. The introduction of monitoring technologies that allow to constantly know the status of the wagon would bring real and concrete benefits to the world of rail transport enabling to optimize the maintenance of rolling stock thus reducing costs but ensuring at the same time a maximization of the safety. Currently, the only information available are provided by the equipment installed along the railway network, separated by tens of kilometers. However, to identify and intervene on an incipient failure, it is necessary to have continuous monitoring and a communication system that can warn the train conductor and the maintenance staff of wagon’s owners. A good monitoring system has to be: cheap, energy autonomous, wireless and reliable. Currently monitoring systems can be divided into two large groups. The former are those developed by universities or research centres within projects financed by third parties, while the latter are monitoring systems developed individually by companies operating in the logistics sector. In light of the existing research projects and products already available on the market, the following thesis work aims to develop a monitoring system demonstrator dedicated to freight wagons that can demonstrate the effectiveness of these devices. The results of preliminary literature and market analyses served as the base for the realization of a first wired demonstrator. All the subsystems of the first demonstrator were long tested in laboratory in order to guarantee the maximum reliability of the device and maximum repeatability of the recorded data. The parameters monitored were the pressures of the pneumatic braking system, the temperature of the cast-iron brake blocks and the dynamics of the body frame. The second demonstrator developed was significantly more complex. In fact, it consists of two wireless units: a base station which represents the further development of the first demonstrator and a completely new axle box node monitoring system. From the analysis of the brake block temperature data two fundamental aspects emerge. The first is the need and importance of maintaining the braking system always in good conditions, doing maintenance in line with the regulations. The second is related to the adoption of new brake blocks in synthetic material. In fact, in addition to the complete review of the brake system as prescribed by the regulation, also the material of the wheelsets must be suitable for the use of new type of brake blocks. Another aspect subject to monitoring in this work is the vibration monitoring. Vibrations of particular interest for freight wagon monitoring are those along the vertical axis and the longitudinal axis. The accelerations along the vertical axis in fact describe the stability of the vehicle and its interaction with the rails. Vertical acceleration is a parameter that allows to determine if the wagon is traveling safely or not. In fact, this parameter makes it possible to identify a possible derailment, if the acceleration level recorded is anomalous. The longitudinal acceleration is a parameter monitored by all the railway monitoring devices present on the market. It is important to know the longitudinal accelerometric levels both in the phases of train composition and during the braking operations in order to identify possible incorrect behaviour. The second demonstrator allowed to monitor the external temperature of the axle box cover and verified the correct behaviour of bearings. The most important result of the second demonstrator was the creation of a wireless network that makes it possible to monitor any quantities without invasive wiring. The creation of a wireless network has also required the development of power saving algorithms for the reduction of energy consumption in order to obtain the maximum operating time. In both prototypes developed, the monitored parameters were very numerous and were sampled with a very high frequency, especially those related to temperatures and pressures. This is a typical feature of the demonstrators. Instead, in order to monitor and study the phenomena related to the dynamics of the wagon it is necessary a sampling frequency as the one adopted. The developed prototypes, even if marked by a strong manual activity, have shown a very high reliability. Monitoring all these parameters for such a long distance led to the creation of a large database. Generally, only large industrial groups can boast such prolonged tests. The prototypes made, thanks to their hardware and software effectiveness, were the basis for the most complex monitoring system that we have set ourselves to achieve with the SWAM Rail project. In conclusion, the project carried out in these three years has therefore obtained as results the realization of demonstrators of monitoring devices, the collection of data that would allow to understand and study the operation of a wagon in optimal maintenance conditions, the development of thermal models and the identification of threshold parameters for delimiting conditions of normal operation by fault conditions.