1,721,332 research outputs found
Development and validation of odometric algorithms for railway control and monitoring systems [Sviluppo e validazione di algoritmi di odometria per sistemi di controllo e monitoraggio ferroviari]
No full textPresent railway systems need amomatica devices for train running control because of the high speed and the higher and higher safety, efficiency and reliability levels required. A fundamental part of these control systems is the so-called odometry that is the set of equipment and software procedures that allow to know with continuity position and speed of the running trains. The odomeiric system validation is carried out on the basis of a series of tests that have to reproduce the highest possible number of cases that could actually occur (degraded adherence conditions axle locking, fault of sensores, etc., This paper describes the operation principles of the control and monitoring systems that are presently in a development and implementation phase at both national level (SCMT system) and European level (ERTMS). Some possible solutions for the odometric system are then illustrated. A software model for train simulation is finally described; this model will be able to be utilized for the odomeiric system validation without resorting to trial runs or anyway reducing their neccessity
Localization algorithm for a fleet of three AUVs by INS, DVL and range measurements
No full textThe strong research efforts undergone in Marine Robotics during the last two decades open great possibilities for maritime operations. Autonomous Underwater Vehicles (AUVs) take the crew away from dangerous situations at depths of sea, with available and cost-affordable technology. MDM Lab, the Laboratory of Mechatronics and Dynamic Modelling of the University of Florence, is partner of the Thesaurus project, funded by Regione Toscana, with the aim of designing a moderate-cost AUV, called Tifone, to be used, in swarm, for research and monitoring of archaeological sites. In this paper we propose a Localization Algorithm for a fleet of three vehicles and a surface support ship which employs several sensors. Each AUV is equipped with low-cost sensors such as IMU, magnetometer and depth sensor; two of them have an high accuracy velocity sensor such as the Doppler Velocity Log. Acoustic modems, used for communication between AUVs, can provide the time of flight from an AUV to an another one. The positions estimated with a Range-Based algorithm fuse with the ones estimated by INS&DVL, avoiding unbounded error growth in the position estimate of the AUVs. © 2011 IEEE
Regenerative braking in high speed railway applications: Analysis by different simulation tools
Full text linkTechnical investigations continuously evaluate the possibility to recover significant amount of braking energy. The application normally involve conventional tramways, characterized by several stops in short-range routes. However, this possibility is becoming more and more attractive also when high-speed trains are considered. In fact, braking energy can be recovered during entry in the station, and delivered later to other trains engaged in starting acceleration. In this work, authors propose an approach based on simplified models performed with object-oriented tools as Modelica or Matlab-Simscape, which easily introduce several advantages in modelling and simulation techniques. The approach has been applied to the preliminary evaluation of one energy storage system installed along a DC line, considering a high-speed train with distributed traction power as the new Italian ETR 1000
Identification of the main hydrodynamic parameters of Typhoon AUV from a reduced experimental dataset
Full text linkIn this research work a case study dealing with the identification of the main hydrodynamic properties of an Autonomous Underwater Vehicle (AUV) is presented. The vehicle is the Typhoon-class AUV developed by the Department of Industrial Engineering of the University of Florence, Italy. The identification of the main hull hydrodynamic parameters is very important for the tuning of an accurate dynamic model of the vehicle, which could be used for several purposes including the development of model based localization and navigation filters. The authors describe the simplified identification procedure adopted for the Typhoon AUV starting from a reduced experimental dataset obtained during some missions at sea performed in 2014 in Biograd na Moru, Croatia
Online Identification of Thevenin Equivalent Circuit Model Parameters and Estimation State of Charge of Lithium-Ion Batteries
Full text linkOn Electrical and Hybrid Vehicles (EVs, HEVs), energy is stored in accumulators, mainly electro-chemical batteries. A reliable and cost effective management of energy storage system is a key point for the development of such devices, their durability and for vehicle performance optimization. This requires the accurate estimation of the battery state over time and in a wide range of operating conditions. The battery state is usually expressed as State Of Charge (SOC) and State Of Health (SOH). Their estimations requires an accurate model to represent the static and dynamic behaviors of the battery. This paper presents a model adaptive Unscented Kalman Filter (UKF) method to estimate online SOC of Li-ion batteries. The proposed approach uses a Recursive Least Squares method to update the UKF model parameters during a discharge period. The effectiveness of the method has been verified based on real data acquired from five LiFePO4 battery packs installed on a working EV
Preliminary design and fast prototyping of an Autonomous Underwater Vehicle propulsion system
No full textThe Mechatronics and Dynamic Modelling Laboratory of the Department of Industrial Engineering, University of Florence, as a partner of THESAURUS (Italian acronym for ‘TecnicHe per l’Esplorazione Sottomarina Archeologica mediante l’Utilizzo di Robot aUtonomi in Sciami’) project, has developed an innovative low-cost, multirole autonomous underwater vehicle, called Tifone. This article deals with the adopted methodologies for the autonomous underwater vehicle design: in particular, the main focus of this study is related to its propulsion system. According to the expected performances and requirements of THESAURUS project, the vehicle has to maintain good autonomy and efficiency (typical features of an autonomous underwater vehicle), with high manoeuvrability and hovering capabilities, which are more common of remotely operated vehicles. Moreover, cooperative underwater exploration and surveillance involve the use of a swarm of vehicles. In particular, the optimization of costs versus benefits is achieved through the design of a fleet of three multirole vehicles. Each autonomous underwater vehicle has five controlled degrees of freedom, thanks to four thrusters and two propellers: in this article, the preliminary design criteria concerning the vehicle and the design and testing of its actuation system are described
Design of a modular propulsion system for MARTA AUV
No full textThis work deals with the design of the propulsion system of a modular AUV (Autonomous Underwater Vehicle) considering different kinds of electrical propulsion systems. In particular, the authors introduce the design criteria followed for the preliminary testing activities and the methodologies adopted for fast testing and prototyping of the proposed solutions. This is a quite important topic considering small production series and the high customization and the reliability required by this kind of applications
A Railway Vehicle Multibody Model for Real-Time Applications
No full textHardware in the loop (HIL) techniques are widely used for fast prototyping of control systems, electronic and mechatronic devices. In the railway field, several mechatronic on board subsystems are often tested and calibrated following the HIL approach. The accuracy of HIL tests depends on how the simulated virtual environment approximates the physical conditions. As the computational power available on real-time hardware grows, the demand for more complex and realistic models of railway vehicles for real-time application increases. In past research activities, the authors worked on the implementation of simplified real-time models for several applications and in particular for an HIL test rig devoted to the type approval of wheel slide protection systems. The activity has then been focused on the development of a three-dimensional model of the dynamics of a railway vehicle for more complex applications. The paper summarises the features and the results of the study
Fast calibration procedure of the dynamic model of an autonomous underwater vehicle from a reduced set of experimental data
No full textAUVs (Autonomous Underwater Vehicles) represent an interesting industrial product with applications ranging from the monitoring of cultural and natural heritage to the inspection of underwater plants for the Oil and Gas industry. Development of AUVs also represents an interesting challenge for researchers and engineers involving a melting of different competences of robotics, mechanics and mechatronics. In particular, this paper is focused on the simulation, identification and validation of simplified hydrodynamic models that can be used for the overall verification and simulation of vehicle performances including aspects related to manoeuvrability and controllability of the system. The identification and validation process described in this work is based on past experiences with the Typhoon AUV built by the MDM Lab (Mechatronics and Dynamic Modelling Laboratory) of the University of Florence, Italy
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