As the maximum speed of high-speed trains increases, flow-induced vibration of trains in tunnels has become a subject of discussion in Japan. In this paper, we report the result of a study on use of modifications of train shapes as a countermeasure for reducing an unsteady aerodynamic force by on-track tests and a wind tunnel test. First, we conduct a statistical analysis of on-track test data to identify exterior parts of a train which cause the unsteady aerodynamic force. Next, we carry out a wind tunnel test to measure the unsteady aerodynamic force acting on a train in a tunnel and examined train shapes with a particular emphasis on the exterior parts identified by the statistical analysis. The wind tunnel test shows that fins under the car body are effective in reducing the unsteady aerodynamic force. Finally, we test the fins by an on-track test and confirmed its effectiveness.
A quantitative evaluation method for passenger rooms of light rail vehicles from viewpoint of comfort and accessibility is proposed as the result of physical modeling of in-vehicle behavior of passengers upon Gibson's ecological psychology approach. The model parameters are identified from experiments at real vehicles at the depot of Kumamoto municipal transport and at the full-scale mockup of the University of Tokyo. The developed model has realized quantitative evaluation of floor lowering effects by abolishing internal steps at passenger doorways and door usage restriction scenarios from viewpoint of both passengers and operators in comparison to commuter railway vehicles.
A physical model of dwell time at transit stops for LRT is developed from observed behaviors of passengers at Kumamoto municipal transport in commercial operation and time component measurement experiments at depot for parameter identification. The developed model is able to express waiting queues of sequentially arriving and leaving passengers at the boarding and alighting doors for variety of LRV usages in detail. The model has realized precise comparison of low-floor vehicle introduction and door usage improvement scenarios in connection with fare transaction methods.
This report evaluates a position of SOC (State of Charge) along with a down hill drive on a real world to its simulation on an emission chassis dynamometer with a gradient road load. On a down hill drive, a vehicle kinetic energy regenerates the battery continuously and an amount of charge volume which shifts the battery SOC up. Excessive charge is a negative factor for the battery life which is designed both a long term of life and a long distance of drive. This regenerating driving mode could not be evaluated on a flat road. A gradient drive way or a gradient simulation system forced energy into a vehicle could evaluate the mode. To evaluate, on the one hand some necessary investigation is carried out to a realization of a down hill drive simulation on an emission chassis dynamometer and problems hitting upon the investigation has been clarified. On the other hand the real world data driving down hill is measured by HEV (Hybrid Electric Vehicle). The real world data collected by GPS (Global Positioning System) has fluctuated widely. This report proposes a method of spline interpolation to the data for a chassis simulation test and reviews the results of the test to the real world mode and evaluates the studies. And here we also report an applied chassis simulation for the study of this method.
This study seeks to design a lane keeping controller for motorcycles and to evaluate it by computer simulation with a four-degree-of-freedom model and a rider control model. We applied the optimal control theory to the lane keeping controller as a model-based control. By examining the computer simulation with the rider-in-the-loop system consisting of the motorcycle, the controller, and the rider control model, good lane following performance is achieved without interference between the control input and the rider's input. In addition, the virtual point regulator, which compensates the lateral displacement at the virtual point ahead of the vehicle, corresponds to not only the steering torque disturbance but also the lateral force disturbance by choosing the distance to the virtual point.
Soil-tire system interaction is a fundamental and important research topic in terramechanics. We applied a 2D finite element, discrete element method (FE-DEM), using FEM for the tire and the bottom soil layer and DEM for the surface soil layer. Satisfactory performance analysis was achieved. In this study, to clarify the capabilities and limitations of the method for soil-tire interaction analysis, the tractive performance of real automobile tires with two different tread patterns—smooth and grooved—was analyzed by FE-DEM, and the numerical results compared with the experimental results obtained using an indoor traction measurement system. The analysis of tractive performance could be performed with sufficient accuracy by the proposed 2D dynamic FE-DEM. FE-DEM obtained larger drawbar pull for a tire with a grooved tread pattern, which was verified by the experimental results. Moreover, the result for the grooved tire showed almost the same gross tractive effort and similar running resistance as in experiments. However, for a tire with smooth tread pattern, the analyzed gross tractive effort and running resistance behaved differently than the experimental results, largely due to the difference in tire sinkage in FE-DEM.
This paper is an evaluation study of electric loads of a production type of HEV (Hybrid Electric Vehicle) under a commuting monitor in Beijing. The monitor was implemented with a half year between hot and cold season by Japanese resident staff drove the vehicle mostly from house to the office. The commuting monitor analysis is done with the data to the same route and the same driver. The observation study of the commuting monitor reveals the following technical findings. Motor re-generation energy gradually decreases from hot season to cold season. Mahalanobis distance analysis could be found out the cause of the electric energy decrease when air conditioner unloaded. The high level of the air conditioner load affects the vehicle input (throttle openings). Although the re-generation load changes along with the environment temperature, the motor-assisted input load tends to steady states. That means the engine is supplied almost steady power from the motor irrespective with environment temperature. Battery keeps control the temperatures refer to environment temperature level. The hybrid air conditioner system worked efficiently which revealed with the difference of load levels between a travel mode and an idling stop mode. There is no notable running difference between an idling mode and the idling stop mode both in summer and in winter.
These days, the dynamically stabilized two-wheeled vehicles are investigated as a form of the new personal mobility vehicle. With the control theory of the inverted pendulum, they are kept in equilibrium. It is important to investigate the stability of the dynamically stabilized vehicle especially on a rough road. For this background, the authors investigate the responses of the inverted pendulum, which is stabilized by an optimal controller, to vertical vibrations. With theoretical analysis, numerical simulations and experiments using a large scale vibration exciter, stability to vertical vibration is examined. The results show the system dynamics are governed by the Mathieu equation, thus the amplitude ratio reaches its peak when the frequency of the forced vibration is twice the natural frequency of the controlled inverted pendulum system. The simulation using the parameter of the dynamically stabilized vehicle was also performed and unstable region for the vehicle was found.