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Reducing derailments of freight trains is of utter importance for improving railway transportation since derailments lead to large service disruption, economic losses and risk related to transported goods. The present paper studies low-speed (below 30 km/h) derailment of freight trains, performing experimental full-scale tests, using an instrumented wagon equipped with a commercial derailment detector. Specifically, the dynamics of a freight wagon during wheel-climb derailment and the motion with one axle derailed are investigated. During the tests, accelerations were measured at the bogie and at the carbody. Moreover, the intervention of the derailment detector was monitored to assess possible causes of false tripping or miss-detections. Two loading conditions were analysed: empty and loaded wagon. Main achievements may be summarised as follows: (1) the activation of the derailment detector is always triggered by impacts between the axle-box and the rail; (2) if the wagon is empty, vibrations induced by a derailed axle over the sleepers strongly depend on vehicle speed and they may not trigger the derailment detector in the range 15–25 km/h; (3) derailment detectors must be installed at both ends of each wagon. This information may be used to develop derailment detection algorithms integrated into electric control units with computing capabilities.. [ABSTRACT FROM AUTHOR]

Automobiles are becoming more and more complex as multiple control systems are integrated into the vehicle platform. This paper investigates the coordination of active rear steering (RWS) and torque vectoring (TV) – which is enabled by independent electric motors at the rear axle – in controlling vehicle lateral dynamics. The proposed controller aims at enhancing vehicle handling performance and stability while cornering. The coordination of the two actuators is achieved by weighting their contribution based on their impact on vehicle dynamics according to the working condition. The impact of each control system is assessed by means of phase portraits. These plots are a very powerful tool for analysing vehicle nonlinear dynamics as they readily display vehicle stability properties and map equilibrium point locations and movement to changing parameters and control inputs. Based on phase portrait analysis, a performance index is thus proposed, which weights more the control action (TV or RWS) capable of leading the vehicle at the nearest equilibrium point with the fastest rate. The controller performance is assessed through numerical simulations carried out using a nonlinear 14 dofs vehicle model. Results are compared with ones of the two controllers alone (RWS and TV) in different manoeuvers and adherence conditions. [ABSTRACT FROM AUTHOR]

Electric motors offer the possibility to control the braking torque in a more precise way than the hydraulic circuit. The applied torque is in fact measured and so it can be used to feedback the controller. Moreover, this information can be used to estimate the tyre–road friction coefficient, before potential friction is reached. The present paper proposes a novel ABS control strategy for electric vehicles with distributed motors. The controller is a six states machine that uses the information on applied braking torque provided by the electric motors. This information is of paramount importance to understand when the wheel reaches the peak of the braking force. Simulation results shows the benefits of the proposed strategy, comparing the results with state of the art acceleration-based controller. [ABSTRACT FROM AUTHOR]