Search

Assessment of railway wheel slide protection (WSP) systems involves the execution of complex experimental activities that are quite expensive and time-consuming, since they involve the physical reproduction of degraded adhesion conditions on a real railway line. WSP is devoted to regulating applied braking forces to avoid excessive wheel sliding in case of degraded adhesion conditions between wheel and rail. WSP must be also compliant to safety specifications related to assured braking performances and consumed air. Hardware in the loop (HIL) testing offers an affordable and sustainable way to accelerate these activities optimizing cost, duration and safety of experimental activities performed online. HIL test rigs are subjected to continuous updates, customization and natural ageing of their components. This work investigates the criteria that can be adopted to assure a continuous monitoring and validation of a real WSP test rig, the Italian test rig of Firenze Osmannoro.

•One important bonus of railways comes from braking energy recovery.•Braking energy of trains can be recovered in storage systems.•High power lithium batteries and supercapacitors have been considered.•Storage systems can be installed on-board or along the supply network.•A simulation tool has been realised to achieve a cost/benefit analysis.

The PROTEUS project involves the construction of a self-propelled and floating amphibious machine for near shore geological surveys. In this context, the development of a wireline core drilling device was tackled, evolving with respect to existing models and responding to the specificities of the new application. In the preliminary phase, comparative research was carried out both through market research and through reverse engineering activities on core drill models deemed suitable for the purpose, thus identifying the functional priorities and criticalities of the existing material through the ex-post analysis of the subject elements to wear and tear. Once the requirements of the new core drilling device were formalized, the constructive layout was defined, giving priority to functions such as sample management, interlocking and rapid disengagement from the drilling actuation system. The construction details of the mechanical coupling profiles were then optimized by simulation in a multibody software environment, in order to ensure full functionality even in harsh environments, typical of the application, making an advancement with respect to the previously identified reference solutions. Finally, the executive design of the component was carried out by introducing the corrections deriving from the simulation results and considering different solutions in relation to the material adopted and its production needs through machining processes.

The objective of this work is the development of an innovative actuator for Velan ABV S.p.A., which is mainly used for control and special on/off applications where high efficiency and linear behaviors are desirable specifications. The main performances of the proposed actuator, which has been protected by a patent, have been compared with a conventional scotch yoke one, using both the simulation results and the experimental data. In order to measure the efficiency and the dynamical response of the actuators, the authors have designed a hydraulic test rig, configured to fulfill different testing procedures. In this way, it is possible to perform both static tests to identify actuator efficiency and dynamic hardware-in-the-loop tests in which an assigned load or valve impedance function is simulated to verify the response of the tested object in realistic operating conditions. Finally, the proposed test rig has been successfully used to perform reliability and fatigue tests in which the actuator is stressed with realistic and repetitive loads. Moreover, the integrated development of both innovative actuator and testing devices is explained introducing interesting concepts whose applications are normally limited to robotics (e.g. impedance and force control) or vehicular technology (e.g. smart suspensions and suppression of vibrations).

In modern railway vehicles, the use of Magnetic Braking Systems is continuously increasing, because they are characterized by high braking performances and low energy consumptions. Hence, the study and the accurate modelling of Magnetic Braking Systems is a very important issue, because they significantly affect the dynamics of vehicle and electrical supply circuit. Usually, the performances of Magnetic Braking Systems are evaluated on test-rigs in order to reduce times and costs of testing phases. For this reason, the authors focus on the development of a complete 3D model of Magnetic Brake System test-rig (built in COMSOL), including all the electromagnetic, circuital and mechanical parts. These parts are often studied separately in the literature; however, a combined analysis is crucial to correctly describe the behaviour of the whole system. The proposed model is highly modular (to describe different Magnetic Brake System test-rig layouts characterized by a different number of magnetic polar expansions) and aims at obtaining a compromise between accuracy and numerical efficiency. Subsequently, a second simplified lumped parameter model derived from the complete one and built in MATLABis developed, to further reduce the computational load without decreasing the results accuracy. In this work, both the models have been developed and validated in collaboration Ferrovie dello Statoand compared with other simplified models present in the literature.

Hazard and operability analysis is a decisive factor to evaluate safety and reliability of plants considering the propagated effects due to consecutive failures of known critical components. A good design and analysis practice increases the robustness of the considered system in different operating conditions; however, in the plant design process, the use of a model-based design approach is fundamental to increase speed, efficiency and reliability. In this work, a tool for the 1-D simulation of thermal hydraulic plants is presented and applied to the analysis of critical system for compressor and gas turbine units, e.g. the lubrication circuits. Different from known commercial products, the proposed tool is implemented to work in cooperation with PidXP™ (the GE Nuovo Pignone P&ID definition tool), and it is optimized for fixed step solvers in order to easily include the rotating machine control logics within the simulation environment (essential prerequisite for hazard and operability evaluations). All the above makes it suitable for the fast prototyping of real time code. Moreover, the proposed tool represents a general tool in the model-based approach, and it can be used as a Simulink™ library of components that have been optimized and specifically designed in order to make easier the automatic generation of simulation models from P&Id schemes and technical documentation, reducing errors associated to data transcription and operator misbehaviour. In this work, proposed approach and test bench on experimental data for validation purposes are shown.

The availability of a reliable speed and travelled distance estimation is relevant for the efficiency and safety of automatic train protection and control systems. This paper investigates the main features of an innovative localization algorithm that integrates tachometers and inertial measurement units. Nowadays, the estimation is performed by an odometry algorithm that relies on wheel angular speed sensors. The objective is to increase the accuracy of the odometric estimation, especially in critical adhesion conditions, through sensor fusion techniques based on Kalman filter theory. The Italian company ECM S.p.A. has supported the project, providing a custom inertial measurement unit based on micro electro-mechanical system sensors for the on-track testing of the algorithm. The preliminary results show a significant improvement of the position and speed estimation performances compared to those obtained with SCMT (Italian acronym for ‘Sistema Controllo Marcia Treno’) algorithms, currently in use on the Italian railway network. A wide set of simulated test results, showing the improvement of the estimation process, is presented and discussed. An accurate train navigation that scarcely relies on information from the infrastructure will open a road map for the development of a more and more effective and efficient exploitation of the railway infrastructure.

The CommsNet 2013 experiment took place in September 2013 in the La Spezia Gulf, North Tyrrhenian Sea. Organized and scientifically led by the NATO S&T Org. Ctr. for Maritime Research and Experimentation (CMRE, formerly NURC), with the participation of several research institutions, the experiment included among its objectives the evaluation of on-board acoustic Ultra-Short Base Line (USBL) systems for navigation and localization of Autonomous Underwater Vehicles (AUVs). The ISME groups of the Universities of Florence and Pisa jointly participated to the experiment with one Typhoon class vehicle. This is a 300 m depth rated AUV with acoustic communication capabilities originally developed by the two groups for archaeological search. The CommsNet 2013 Typhoon, equipped with an acoustic modem/USBL head, navigated within the fixed nodes acoustic network deployed by CMRE. This allows the comparison between inertial navigation, acoustic self-localization and ground truth represented by GPS signals (when the vehicle was at the surface). The preliminary results of the experiment show that the acoustic USBL self-localization is effective, and it has the potential to improve the overall vehicle navigation capabilities.

A comprehension of railway dynamic behavior implies the measure of wheel–rail contact forces which are affected by disturbances and errors that are often difficult to be quantified. In this study, a benchmark test case is proposed, and a bogie with a layout used on some European locomotives such as SIEMENS E190 is studied. In this layout, an additional shaft on which brake disks are installed is used to transmit the braking torque to the wheelset through a single-stage gearbox. Using a mixed approach based on finite element techniques and statistical considerations, it is possible to evaluate an optimal layout for strain gauge positioning and to optimize the measurement system to diminish the effects of noise and disturbance. We also conducted preliminary evaluations on the precision and frequency response of the proposed system.

On railways, the current collection from the overhead line is assured by the pantograph which is an articulated suspension system. Interaction between the contact wire and pantograph produces oscillations which, in order to assure a satisfying quality of current collection, have to be compensated. On high-speed railways, this problem is very important because insufficient quality of current collection involves performance limitations and negative consequences both in maintenance costs and service reliability.A possible solution to improve current collection quality is to optimize the dynamical response of the pantograph suspension system through an active or semi-active suspension system.Trenitalia SPA has financed a research team composed of many Italian Universities (Università di Firenze, Politecnico di Milano, Università di Pisa, and Università di Napoli) to develop an innovative railway pantograph for Italian high speed lines. The activities have been coordinated by Italcertifer. Researchers from Università di Firenze designed the layout of the control system (actuation system, sensors, drive and control algorithm, etc.). In order to improve the tuning of the control strategy, an identification phase has been carried out to obtain a mathematical model of the prototype. Non-linearity of the real pantograph has been take into account by the Bouc—Wen model. The proposed control strategy has been successfully tested on a prototype build by Fabrica Machinale SRL. Experimental results of laboratory tests and performance index of the proposed solution are shown in order to demonstrate the goodness and feasibility of the proposed solution.

The object of this work is the development of an innovative wire actuator in collaboration with Velan ABV S.p.A., which will be mainly used in applications in which high efficiency and linear behavior are desirable specifications. In this work, the main features of the proposed actuator, which is protected by a patent, are evaluated and compared with respect to a conventional solution consisting of a scotch yoke (SY) transmission system. The comparison is performed using both the simulation results and the experimental data. In order to identify the efficiency and the dynamical response of the innovative actuator, the authors have designed a hydraulic test rig, which can be configured to perform different testing procedures. In this way, it is possible to perform both static tests to identify actuator efficiency, and dynamic ones, in which an assigned load or a valve impedance function is simulated to verify the response of the tested actuator in realistic conditions. Finally, the proposed test rig has been successfully employed to perform both reliability and fatigue tests in which the actuator is subjected to realistic and repetitive loads.