[in Japanese]

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There are two types of car-body tilting mechanism for railway vehicles. One is the beam-type tilt mechanism with the tilt angle of about 5 degrees and the other is air spring-type with the tilt angle of about 2 degrees. Since the tilt angle of air-spring-type is too small to reduce stationary lateral acceleration dramatically, the investigation is targeted at the tilting control law and the vibration suppression for the improvement of riding comfort. In this study, analytical models of air-spring-type tilting vehicle are developed using the multi-body software SIMPACK. Using two control methods, the height control and the "height + internal pressure" control, there effects are examined in the simulation. The results were compared with the results from test plant. Consequently, it is shown that the addition of internal pressure control may reduce the roll vibration and potentially contribute to the improvement of riding comfort.

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For suppression of vertical bending vibration of railway car bodies, the authors have developed a damping control system with variable primary vertical dampers. To put this system into practical use, it is important to detect the failure accurately in case some damper fails. This study presents a method for fault detection of primary vertical dampers by using accelerometers mounted on bogie frames for the vibration control. The proposed method is based on the phase difference of the bounce and the pitch mode vibration of bogie frames. Vibration excitation tests are carried out with a Shinkansen vehicle on a testing plant. The damping force of one of the variable primary vertical dampers is switched to the minimum in order to simulate a failure; the vibration control is applied to the other dampers. The results demonstrate that the fault of one damper could be detected effectively by proposed method.

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In order to improve the riding comfort of railway vehicles, we proposed a method to suppress the first mode bending vibration by using the damping control system of axle dampers. The results of running tests using an actual Shinkansen vehicle showed that the control system can effectively reduce the power spectral density (PSD) of accelerations of the carbody floor. On the other hand, the previous researches indicated that on-board passengers make a difference to the bending vibration of the carbody. Therefore, in this study, to confirm the efficacy of the control system regardless existence of passengers, we carried out numerical simulations using 7DOF vehicle model combined with passenger models and excitation tests with/without passengers on a rolling stock testing plant. As the result, we could roughly make clear the influence of on-board passengers to the bending vibration by using the vehicle-passengers model. Furthermore, by using the same control parameters, we verified that the control system could obtain the excellent performance of vibration suppression regardless of the existence of passengers.

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This report describes the development of a displacement-dependent rubber bush to prevent carbody vibration of railway vehicles induced by rotation of wheelset(s) with small mass imbalance. The displacement-dependent property is realized by introducing a small gap between the rubber and the inner fixture, and transmission of the excitation force is isolated by the gap. Excitation tests using a full-scale test vehicle to verify the vibration isolation performance and running stability testing with a bogie are carried out in the rolling stock testing plant at RTRI. Then a series of running tests on a commercial line is conducted and the effectiveness of the displacement-dependent rubber bush has been confirmed.

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We proposed new vibration isolation system transmitted from the elevator traction machine to the adjacent room. This system is constructed with small active mass damper (AMD) attaching on the machine bed of a traction machine. For getting more performance, we evaluated two modeling method for obtaining numerical model of vibration transfer system of a traction machine. One is the method of using experimental modal analysis, and other is the system identification method. As a result, we could get more precise numerical model from system identification method. Based on the obtained numerical model, we designed system controller using LQ control method and investigated the performance of this system with the elevator in our test tower. We could attain to reduce the transmitted vibration to the adjacent room from the traction machine for about 50% or more.

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The authors have developed a noise reduction system to reduce the transmitted sound passing through panels by fixing noise insulation panels consisting of thin plates, piezoelectric materials and control circuits. In the case where an inductance circuit was used as a control circuit, the radiated sound reduced in narrow frequency range. In this paper, we have described a way to spread the frequency range of control by double layer noise insulation panels with piezoelectric material. By the experiment, it was possible to reduce transmitted sound in two bandwidths of frequency. However, the shift in the frequency of control was confirmed by comparing single layer with double layer.

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Structural optimization was applied for a contact-wire/battery hybrid light rail vehicle body structure. Its body structure has an extremely lower height floor due to improving the accessibility for passengers without a platform. This causes several heavier electrical equipments must be attached as the roof-top equipments, which requires additional stiffeners and structural parts around the roof structure and side structure in order to keep strength and durability of the carbody. Topological optimization provided such a new design direction for the carbody structure as the special truss structure, which is in contrast to the usual semi-monocoque carbody construction. This newly designed structure also achieved reducing weight of the carbody. This numerical calculation also investigated effects of the arrangements of roof-top equipments as well as a large number of battery cell units in terms of the structural optimization.

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By using a new monitoring system for derailment coefficients, the authors have succeeded in measuring derailment coefficients everyday on every curve of a commercial line. From these data, we could evaluate the variations of derailment coefficients statistically which change according to the track conditions and train boarding conditions. In this paper we introduce the commercial running data analysis, and propose a new management method for maintaining good railway track conditions.

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The characteristic of on-centered steering stability is important to contract a control system for autonomous vehicle, and we need to investigate the systematic treatment. As a first stage of this research, we have constructed a steering model with circumstantial stiffness of on-centered steering which is decreased at neutral region. From the result, it is found that the model has good expression to the experimental result.

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Large vehicle as a construction vehicle is bounced because of running rough road. This vibration bounces the cabin and transmits the driver. The driver gets tired and his efficiency of work grows worse. This paper examines improving a ride quality and reducing a ride quality aggravation affected a load variation by vibration control system with an active seat suspension. The controller was designed by applying the H-infinity control theory. The numerical simulation results show that the ride quality for driver improved by the active seat suspension.

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The authors propose to use a flywheel as a stabilizer for a heavy vehicle by using gyroscopic effect. A typical flywheel is composed of a rotating disk and gimbals, which absorb the gyroscopic effect, while supporting the rotor. To produce the gyroscopic effect to stabilize the heavy vehicle, the proposed system constrains the gimbal when the roll of the truck becomes large and reach beyond the threshold value. The stability of the heavy vehicle with the proposed flywheel system and the inertia moment of flywheel necessary for stability control are examined using multibody dynamics software; ADAMS. It was found that the proposed control system is effective for prevention of roll turn over and energy storage system.

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Harvested fruits and vegetables are mainly transported by trucks where vibration generated by their motions usually causes cargo damages. Because strawberries are very delicate, the development of the method for decreasing damages of them during transport is required. In this study, we create a model of strawberry cargo to analyze its vibration characteristics during transport. Additionally, we propose a method and the development of an equipment for vibration suppression control. In this phase, we conducted sinusoidal vibration tests of strawberry cargo and simulations by the created model. The parameters of the model such as constant of spring and viscous damping coefficients were set by trial and error. The model validity was shown, and modes of vibration in each direction and natural vibration frequencies were revealed.

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In design method of propellers, the distribution of circulation that gives highest efficiency was defined by Goldstein after he solved "Betz condition" in 1920s. On the other hand, optimum design method for ducted fans has not been developed yet though the ducted fan used by UAV, VTOL, etc., has increased in recent years. We developed the design method that solves the distribution of circulation that gives highest efficiency in the configuration of low disc load which is called "ducted propeller." We tested several conditions and came up with these important characteristics.

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We experimentally investigated the dynamics of railway vehicles, which derail from the top surface of a rail onto the ground, using full-scale models of one bogie and a half carbody on the large shaking test facility. The dynamics of derailing vehicle were as follows: 1) After a wheel leaved the top surface of a rail, the wheel firstly landed on the ground. 2) Then, the gear case next to the wheel hit the inner side surface of the rail. 3) Finally, the bogie slightly yawed and the L-shaped guide under the axlebox at the diagonal position of the gear case hit the outer side surface of the opposite rail. During the derailment, the maximum piston velocity of the lateral damper was about 0.6 m/s and the maximum action force of the L-shaped guide was about 60 kN.

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It is important to execute a study on reduction of damage of the railway vehicle caused by natural disasters. Authors made a 1 to 10 scale model vehicle for various tests such as a derailment test, an overturning test, which might be difficult to be performed with a full-scale model, and carried out shaking tests under several conditions to find out the amplitude-frequency response of this model vehicle. The results were compared with a half-car vibration models, and we obtained the following conclusions. First, the result of the vertical shaking tests without use of dampers in the model vehicle can be explained well by the often-used half-car model, however it is not the case for the lateral shaking tests. Then the authors proposed an improved half-car model and the model could explain the lateral shaking tests result well. Second, the result of the vertical shaking tests with use of axle dampers in the model vehicle can be explained well in the range up to 10Hz, however it differs from the calculated results in the range above 20Hz. Third, the result of the lateral shaking tests with use of lateral dampers in the model vehicle agrees with the calculated results at least qualitatively, although there are major differences between them at the frequency of 4.5Hz and 6Hz, whose reasons have not been found clearly. Finally, the result of shaking tests with use of all dampers in the model vehicle are about the same as the result with use of axle dampers for vertical shaking tests, and as the result with the use of lateral dampers for lateral shaking tests, respectively.

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To reduce secondary damage after the train is derailed by the earthquake vibration, it is important to know the behavior of the train set running at the high speed. When the derailed wheelsets run on a ballasted track, derailing wheels run on the sleepers and running resistance occurs to the vehicle because the wheels hit and bounce to the sleepers. To understand the running resistance and estimate the train set dynamic characteristics, we performed the experiment where 1/10 scaled vehicle model ran on steel sleepers at high speeds. We show the following results. (1) Equivalent running resistance coefficient was calculated from entrance and exit running speed of the test area. From the comparison between running on the flat plate and running on the sleepers, resistant coefficient on the sleepers was remarkably larger at 10〜70km/h speed than that on the flat plates. (2) There seems to be a relation between the size of the equivalent running resistance coefficient and the number of sleeper traces.

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In order to prevent the derailed vehicle from deviating from the track in the case of earthquakes, authors have developed a post derailment stopper attached to a bogie frame. For the development of the stopper, we conducted running tests under derailment conditions using real bogies and tracks. In addition, we have developed the vehicle dynamics model with the stopper based on the results of running tests. In this paper, we introduce the model for derailed vehicle and analyze the motion of the bogie frame and the stopper.

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Road roughness is a significant factor to the ride comfort and the maneuverability of an automobile. In this paper, we propose an estimation method of a road profile from measurement data during running test with an experimental vehicle. The estimation method is based on iterating multibody analysis, and uses multibody vehicle model based on an electric vehicle developed in our laboratory. In order to confirm of the validity of the estimation method, running test was conducted with this electric vehicle. Estimated road profile was compared to an actual road profile, and the accuracy of an estimated road profile was evaluated.

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Three-dimensional motion analysis is necessary to describe the complex tire behavior on soft ground due to the deformation of the tire and the landform of the soft ground such as the ground heaving in the vicinity of the tire side edge. We developed the three-dimensional interactive model for the performance of the tire on soft ground that were composed of the distributed lumped mass-spring model as the tire, Discrete Element (DE) model as soft ground. In the present study, we have extended the previous model by dividing the soft ground into the upper and the lower soft ground, and by adding the lug to the tire with considering the contact geometry with soft ground. Numerical simulations of the tire behavior on soft ground have been carried out under several conditions using the proposed model. The numerical results showed that the three-dimensional motion analysis of the tire behavior on soft ground could be conducted, and that the proposed model could be validated through comparison with previous experimental results on the tractive performance of the tire on soft ground.

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This paper proposes variable camber angle control by optimize tread use on the tire with two layer compound for tread part to improve automobile fuel efficiency. Based on this concept, the tire with two tread regions was developed: one with low rolling resistance (low loss) and the other with high grip. Initially the tire characteristics were analyzed using a tire testing machine. For comparison, the characteristics of a low loss tire and a high grip tire were also measured. The effect of proper use of the low loss and high grip regions was confirmed. In vehicle experiments, the tire with two layer compound for tread part was evaluated for both rolling resistance and full braking characteristics. The proper combination of camber control and the tire with two layer compound for tread part was shown to result in both reduced fuel consumption and improved braking performance.

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In the theoretical research maneuverability and stability of the two-wheeled vehicle, the most famous one is called four degree of freedom model that sharp announced. The dynamic characteristic of the tire is considered in this model, cornering stiffness and camber stiffness are generated by the delay for the sideslip and camber angle by the first. However, when such tire characteristics are used, the vibration phenomenons wobble and weave is not theoretically expressible. So this paper, it focuses attention on the side rigidity and twist rigidity of the tire and analyzed the tire model consider the rigidity value into the four degree of freedom model.

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In recent years, many cranes are used as transportation devices in wide industrial fields. Especially, the overhead crane is known as a famous example of cranes. When the trolley moves and the length of the wire rope changes at the same time, undesired vibration with variable frequency occurs, since the natural frequency of the crane changes with the length of the wire rope. For safe and efficient operations, it is necessary to control the vibration. However, it is difficult to suppress the vibration with ordinary linear controller because of nonlinearity of the cranes. Therefore, in this study, we first derive an analytical model of the overhead crane as a linear parameter varying (LPV) system. Then, we design the controller using Dual Model Matching (DMM). The effectiveness of the controller is verified through numerical simulations.

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The vertical elastic vibrations of railway vehicle carbodies are needed to reduce from the viewpoint of riding comfort. In particular, more than one elastic vibration modes having natural frequencies around 10Hz are known to be affect riding comfort. To reduce those elastic vibrations, we suggested a method by using active mass dampers (AMD). This paper describes the excitation test using a test vehicle in the rolling stock testing plant at RTRI to verify the effectiveness of the proposed method. Two linear actuators are applied as AMDs and the vibration reduction effect for major two elastic vibration modes and improvement of riding comfort are investigated.

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This paper proposes a control scheme to reduce the vertical vibration of carbody by the traction motor torques. Traction motors of electric railway vehicles are mostly driven by 1-pulse mode which the voltage of PWM inverter was saturated. In 1-pulse mode, the torque control characteristics of the motor deteriorate because the controller can control only the phase of the output voltage. This paper describes the simulation of the control scheme with 1-pulse mode. The simulation results reveal that the control scheme with 1-pulse mode can reduce vertical vibration as same as in the case of the control scheme with vector control.

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This study examines the collision avoidance system for motorcycles by automated steering control. The Model Predictive Control (MPC) is applied with the constraint on the rolling motion by considering the rider's body movement in emergency avoidance. By examining collision avoidance simulation, the MPC improves the avoidance performance in comparison with the LQ controller. The MPC also has some robustness.

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This paper examines validity of variable characteristics steering system with PID-control for the emergency avoidance performance in automobile by computer simulation. K_D -T -J Map is proposed, and effectiveness of P and D-Element is shown by using the map. As a result, it is shown that even an unskilled driver and a novice driver can do the emergency avoidance operation like a skilled driver using variable characteristics steering system with PD-control.

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A design method of an active front wheel steering controller that guarantees closed-loop stability under lateral tire force saturation is proposed. The proposed controller uses information on lateral tire force to counteract the destabilizing effects caused by lateral tire force saturation. The controller suppresses magnitude of the slip angle while lateral tire force is saturated. Effectiveness of the proposed method is shown through numerical simulation results.

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In recent years, the developments of steering control are proceeding for assisting driver's maneuver. Meanwhile, driver characteristics are important that steering assist system is consist mainly of driver. Thus, the improvement of the performance as man-machine system can be expected by the designing of the closed-loop system including the driver characteristics. We have been discussed optimal steering assist system with assumption of crosswind disturbance in lane following situation in the past. In this study, assist system was examined by using curve task to improve robustness of control system. Here, we aimed for assist system having higher level of maneuverbility performance by tailor the driver characteristics to the individual.

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An integrated control system for a semi-active suspension system with variable stiffness stabilizer has been proposed. In this study, in order to improve road holding in addition to ride comfort and handling performance of the proposed method, a roll stiffness distribution control is proposed. In the proposed method, frequency weights of control input for variable stiffness stabilizer are scheduled according to the error to target yawrate. The computer simulations were carried out to verify the availability of the proposed method when vehicle runs on the corner and uneven road section.

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This paper presents the laboratory experimental result carried out in order to investigate the relation of a tangent force between a wheel flange and a rail under the conditions of different environmental temperature and relative humidity. In the experiment, we used two types of cylinder test specimens (The type which has fine unevenness on a contact surface, and the type which is not.) assuming an actual wheel and an actual rail, and investigated the relation of tangent force and the existence of unevenness of a contact surface under the conditions of different environmental temperature and relative humidity. Consequently, under the conditions which do not have fine unevenness on the contact surface of a test specimen, it turned out that there is a tendency for a tangent force to become less on condition of 60% over of environment in relative humidity, regardless of room temperature. However, on the conditions which have fine unevenness on the contact surface of a test specimen, we could not observe the affect of room temperature and relative humidity.

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Rail grinding as a part of maintenance of railway track is executed for the purpose of reducing damage on rails and environmental noise etc. When executing grinding to remove head checks at rail gauge corner in curve sections, the grinding-rail profile and grinding range should be carefully considered so as not to induce flange climb derailment. The authors have implemented numerical simulation of a vehicle running on ground rails in curve sections at a low speed, and examined running safety against flange climbing characterized by such factors as the wheel-load imbalance and curve radii. Based on the simulation result, the authors have proposed limits of a grinding range, a grinding angle and a curve radius, which should be abided by for securing safety against flange climb derailment.

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