Adhesion Increase Method for Shinkansen Train under Snowfall in Winter

With the use of the ADAMS/Car and vehicle dynamics model, the authors established a road model and coupled model of the car and road. By changing the road surface friction coefficient of the ADAMS/Car, the vehicle driving conditions were studied on dry pavement, wet pavement, pavement in rainy weather, pavement in snowy weather, and icy pavement. Through the simulation analysis of the three driving conditions, the curves of lateral displacement, curves of lateral force, and braking distance curves were obtained under different road surface friction coefficients, which can be used to analyze the safety of a car in rainy and snowy weather.

Abstract. As autonomous driving technology advances, ensuring the system's safety in rain and snow has emerged as a pivotal research topic. In rainy and snowy weather, rain and snow can generate noise points within the point cloud captured by the Light Detection and Ranging (LiDAR), significantly impeding the LiDAR's sensing capability. To address this problem, we first manually label the point cloud data gathered in rain and snow, categorizing all points into noise points and non-noise points. Subsequently, we analyze the intensity and spatial distribution characteristics of the rain and snow noise points and employ the gamma distribution curve to illustrate the spatial distribution characteristics of these noise points. Finally, we propose a Low-Intensity Dynamic Statistical Outlier Removal (LIDSOR) filter, an enhancement of the existing Dynamic Statistical Outlier Removal (DSOR) filter. Experimental results suggest that the LIDSOR filter can effectively eliminate rain and snow noise points while preserving more environmental feature points. Additionally, it consumes fewer computational resources. The filter we propose in this paper significantly contributes to the safe operation of the autonomous driving system in diverse complex environments.

In this paper, a novel sensor system is presented for estimating the velocity using a modulated motion blur. By moving a camera mounted on the vehicle body with a specific pattern when the vehicle is moving, the blurred image includes the information of the vehicle velocity of the camera itself. It will be shown that the inclinations of motion blur in a scene are directly related to the velocity vector of the vehicle and the modulation speed. The proposed approach invariant to the exposure time provides the magnitude and direction of the velocity vector with high accuracy and high reliability. In contrast to other approaches using a camera image, our approach requires only 256 × 192 [pixel], and the proposed algorithm is simple and fast. The efficacy of the proposed method is demonstrated through simulations and experiments. The experimental results present empirical evidence to support that the proposed system is robust to climate changes such as rainy or snowy weather. The proposed system is expected to be applicable to vehicular technologies such as the vehicle dynamics controlling system or the vehicle positioning system.

Temperature-dependent crack induced by microstructure evolution in 20Mn2SiMoCuV bainite wheel steel

This study proposes a technique to temporarily improve the friction force by jetting dry air with less than 30% humidity on the contact surface. The tangential contact force was first measured under the condition that a very small amount of water was on the contact surface and the velocity was 30 km/h to confirm that the proposed technique is effective even in rainy weather. The findings revealed that the adhesive force increased by reducing the amount of water on the contact surface. These experimental results indicate that the dry-air jetting technique effectively increases the friction coefficient, even under rainy conditions, because dry-air jetting can remove water droplets on the surface. Subsequently, an experiment was conducted on the tangential contact force using a twin-disc sliding-frictional rolling machine to verify our proposed technique under different dry conditions. The tangential contact force coefficient increased simultaneously with dry-air jetting and remained stable during dry-air jetting under dry and high-humidity environmental conditions. Furthermore, the findings clarified that the tangential contact force improvement effect of dry-air jetting depends on the combination of the contact patch and its surface properties. Finally, based on these experimental results, we compared the same rail vehicles with and without considering the braking distance as an example of a dry-air jetting system application, using a vehicle dynamics analysis constructed using the SIMPACK commercial software. Consequently, the validity of the proposed technique was confirmed for actual rail vehicles.

A new method is proposed for analyzing the nonlinear dynamics and stability in lane changes on highways for tractor-semitrailer under rainy weather. Unlike most of the literature associated with a simulated linear dynamic model for tractor-semitrailers steady steering on dry road, a verified 5DOF mechanical model with nonlinear tire based on vehicle test was used in the lane change simulation on low adhesion coefficient road. According to Jacobian matrix eigenvalues of the vehicle model, bifurcations of steady steering and sinusoidal steering on highways under rainy weather were investigated using a numerical method. Furthermore, based on feedback linearization theory, taking the tractor yaw rate and joint angle as control objects, a feedback linearization controller combined with AFS and DYC was established. The numerical simulation results reveal that Hopf bifurcations are identified in steady and sinusoidal steering conditions, which translate into an oscillatory behavior leading to instability. And simulations of urgent step and single-lane change in high velocity show that the designed controller has good effects on eliminating bifurcations and improving lateral stability of tractor-semitrailer, during lane changing on highway under rainy weather. It is a valuable reference for safety design of tractor-semitrailers to improve the traffic safety with driver-vehicle-road closed-loop system.

Experimental and numerical study on the effect due to passengers on flexural vibrations in railway vehicle carbodies

Recently trains raise speed and reduce the motor vehicle ratio. It is needed, therefore, to utilize adhesion force more effectively. Although several. anti-slip readhesion control methods have been developed, it has become clear that slip and readhesion repeat under strict adhesion conditions as far as they rely on the conventional concept of readhesion control. So we thought about the reason why conventional anti-slip control methods cause slip/readhesion reiteration under strict adhesion condition and have developed a new control method “Anti-slip Readhesion Control Method with Presumed Adhesion Force”. We confirmed in running tests that we can prevent slip/readhesion reiteration and stably control motor currents even under strict or rapidly changing adhesion conditions by using the newly developed control method.

This paper deals with a development of wear model for railway wheel. Wear of the railway wheel is a factor that affects not only the lifetime of wheel but also the performance of railway vehicles such as ride comfort and running safety. Here, practical wear profiles are necessary to reflect the influence of this wheel wear in the vehicle design or the maintenance schedule. However, a lot of time and cost are needed to obtain practical wear profiles through field test. This study aims to a prediction of the wheel wear profile up to the running distance of wheel turning using a multi-body dynamics software SIMPACK. Contact conditions such as contact positions and creep forces between wheel and rail and other components can be obtained from the running simulation. SIMPACK includes a module that can easily treat the wheel-rail contact conditions and calculate the multi-point contact between wheel and rail as well as the one-point contact. Therefore, it is possible to carry out the running simulation using worn profiles of wheel and rail. In this study, the objective is passing through shape curve sections where the wheel wear increases. Thus, the simulation is carried out using the parameter values of vehicle and track considering the subway lines. The value of a wear index is calculated by the method proposed by Krause and Poll. The removed material is proportional to the frictional work dissipated in contact patch and the wear depth is obtained being converted from the removed volume. The worn profile is developed in every running distance of 10,000 km on wheel flange and wheel tread respectively. Also, contact parameters such as rolling radii difference and contact angle difference for the lateral displacements of wheelset are calculated and the lateral forces on both wheels are analyzed in a curved section. As a result, in the comparison with measured wear profiles, it is found that the wear tendency of an actual wheel can be predictable, but the amount of predicted wear differs from that of the actual wheel.

Damage evaluation regarding to contact zones of high-speed train wheel subjected to thermal fatigue

On the Design of Wheel Tread Profile for Two-Axle Railway Vehicle : 1st Report, The Basis of Design for the N-Shape Wheel Tread

This paper presents a theory to utilise the longitudinal vibration in bogies as a dynamic vibration absorber (DVA) to reduce the vertical bending vibration of railway vehicle carbodies in a simple and easy way. This study focuses upon the interaction between carbody vertical bending and bogie longitudinal motion, and the condition for tuning the natural frequency of the bogie motion to the target carbody vibration is derived theoretically using a very simple formula. Numerical and experimental studies are then outlined to validate the theory and formula, and the DVA effects are observed from both of them. The effectiveness of the method is also confirmed from a running test with a Shinkansen train on a commercial line.

By making use of the contour representation of the damping ratio, the influence of the wheelset misalignment on the stability of the wheelset hunting motion can be shown much more clearly, and it is found that the wheelset misalignnmnt diminishes the stability margin in the high speed range, and that, in the (kx ky) plane, kx and ky, are better to be chosen in the region apart from a straight line, ky=1.5kx. Limit cycle analyses by means of numerical integration of the original nonlinear equations of motion show that, as no unstable limit cycle can be found in the stable region of the (kx, ky) plane, it can be said that, in order to analyze the stability of misaligned wheelset motion, it is sufficient to examine the stability of the linearised system.

JR-East has been working on a research and development project to increase Shinkansen operation speed to 360 km/h. Methods of wayside noise reduction arise as major issues when increasing the Shinkansen's operating speed, as it is necessary to keep wayside noise levels within those of existing Shinkansen trains, even at a speed of 360 km/h. Two high-speed test trains were developed: (running only on Shinkansen lines) and (running on both Shinkansen and conventional lines converted to Shinkansen gauge). Both of the trains feature several new types of equipment for reducing pantograph noise and noise from the lower part of cars, which have the greatest impact on overall noise level in series E2-1000, operating at a maximum speed of 275 km/h. Running tests were conducted with the FASTECH360 trains to measure wayside noise at a point 25 meters from the center of the track and 1.2 meters above the ground. The results show that to operate at the same noise levels as trains in service (series E2 and E3 (coupled) running at 275 km/h), FASTECH360S and FASTECH360Z (coupled) would have to run at approximately 330 km/h, and FASTECH360S (solo) at approximately 340 km/h. Although the goal of 360 km/h is yet to be attained, it was confirmed that the countermeasures incorporated in the FASTECH360 trains greatly reduced wayside noise. These measures are used for the new generation Shinkansen trains, Series E5 which have been in operation on the Tohoku Shinkansen line since March 2011.

A large-scale data-based investigation on the relationship between bad weather and taxi tipping