This study assesses the capability of an active steering bogie to run effectively on a curved track. It presents a curvature measuring method that can be implemented in a railway vehicle system to steer a railway vehicle. This method was used to conduct a field test. The angle of attack and lateral force were reduced in a railway vehicle model on a curved track and analyzed. An active steering system was implemented to improve certain states when a railway vehicle runs on this track, such as wear and derailment index. The railway vehicle was also equipped with an active steering bogie to limit lateral contact forces and wear rates between the wheel and the rail. Finally, this paper describes the modeling of this active steering system and of a system to control the performance of a vehicle as it curves. Simulation results with this bogie were better than those obtained with a conventional railway vehicle, including in terms of lateral forces and the wear number of the wheels. Therefore, the proposed model is more effective than conventional systems with respect to operation on a curved track.
In a connected car, the vehicle’s internal network is connected to the outside through communication technology. However, this can cause new security vulnerabilities. In particular, V2X communication, to provide the safety of connected cars, can directly threaten the lives of passengers if a security attack occurs. For V2X communication security, standards such as IEEE 1609.2 define the technical functions that digital signature and encryption to provide security of V2X messages. However, it is difficult to verify the security technology by applying it to the environment with real roads because it can be made up of other safety accidents. In addition, vehicle simulation R&D is steadily being carried out, but there is no simulation that evaluates security for the V2X application level. Therefore, in this paper, a virtual machine was used to implement a V2X communication simulation environment that satisfies the requirements for the security evaluation of connected cars. Then, we proposed scenarios for cybersecurity testing and evaluation, implemented and verified through CANoe Option.Car2X. Through this, it is possible to perform sufficient preliminary verification to minimize the variables before verifying security technology in a real road environment.
Digital redesign is yet another efficient tool to convert a pre-designed analog controller into a sampled-data one to maintain the analog closed-loop performance in the sense of state matching. A rising difficulty in developing a digital redesign technique for trackers with time-varying references is the unavailability of a closed-form discrete-time model of a system, even if it is linear time-invariant. A way to resolve this is to approximate the time-varying reference as a piecewise constant one, which deteriorates the state matching performance. Another remedy may be to decrease a sampling period, which however could numerically destabilize the optimization-based digital redesign condition. In this paper, we develop a digital redesign condition for time-varying trackers by approximating the time-varying reference through a triangular hold and by introducing delta-operated discrete-time models. It is shown that the digitally redesigned sampled-data tracker recovers the performance of the pre-designed analog tracker under a fast sampling limit. Simulation results on the formation flying of satellites convincingly show the effectiveness of the development.
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