In this study, we evaluated the morphing effectiveness of a proposed twist morphing structure through a twisting experiment and a wind tunnel test. The key aspects of the study are as follows: (i) we proposed and fabricated a twist morphing structure with a skin part; (ii) we confirmed that the specimen could be twisted according to the target twist distribution under wind loads (wind speed was about 12m s⁄ speed). Furthermore, the specimen could be twisted regardless of the twisting direction, and the maximum error of the twisting angle was 18.1% at the wing tip; and (iii) we collected aerodynamic data, and calculated aerodynamic coefficients for each angle of attack. The results reveal the proposed structure can contribute to the enhancement of flight performance by twisting itself. This indicates that the proposed twist morphing structure, in which a double cylindrical tube is applied to a spar is effective in terms of structural mechanics and aerodynamics.

抄録全体を表示

Morphing wings, which can deform according to the flight conditions, have attracted much attention because of their potential for improvement in aerodynamic or environmental performance. Many studies have contrived flexible structures for the morphing functions, but they need fluid-structure interaction (FSI) analyses for evaluation. In this paper, a new FSI model that has an excellent balance of time cost and reliability of analyses is suggested. A CFD solver UTCart is used instead of XFOIL, which was adopted in the previous work. It is shown that UTCart outperforms XFOIL in reliability of analyses while XFOIL excels in time cost. The combination of the two solvers, where the aerodynamic calculations in the iteration loop are done by XFOIL and the final calculation of the aerodynamic properties is done by UTCart, is found to be a good model for the FSI calculation.

抄録全体を表示

In this paper, a flexible morphing wing with piezoelectric materials for morphing actuation is studied. It provides a description of the electro-aeroelastic equations of morphing wings taking into account piezoelectric effects, which can be used to actuate morphing wings. The electro-mechanical model is validated by comparing with experimental results. The actuation of rectangular corrugated wing for camber morphing is also verified. Aeroelastic behaviors of a corrugated wing with the piezoelectric actuator are also explored.

抄録全体を表示

To improve the fuel efficiency, commercial aircraft has recently had high aspect ratio wing. However, it increases the wing root bending moment and reduces the performance of wing strength. As a solution to this issue, adaptive wing structures are proposed. The adaptive wing means a wing which can change its shape in flight. The previous research shows that wing root bending moment can be decreased by using adaptive wing structures, but many analysis cases are needed for optimization of the wing root bending moment. This study focuses on the reduction of the high computational cost. A new method for Load Control using Superposition (LCS method) is suggested. By comparing the analysis result of LCS method with that of MSC/NASTRAN, the LCS method are verified. In addition, the LCS method is compared with geometrically nonlinear aeroelastic analysis to evaluate its accuracy for large deflection cases. The large flap angle causes the geometrically nonlinear effect, so it is suggested that the LCS method works only in range of about 10 degrees of flap angles.

抄録全体を表示

Recently, drones have been used in many areas. The object of this research is to make an automatic flight drone, find how the autopilot system controls the drone by investigating its aerodynamic characteristics. The method comprises designing and assembling a drone using Pixhawk, a flight controller; measuring its aerodynamics characteristics in a wind tunnel using a balance system; and analyzing the obtained data. The results clearly showed that the automatic flight system worked under various conditions. Further research is required to find the best PID tuning to adapt the drone to rapidly changing environments.

抄録全体を表示

There is berthing operation as one of the ship maneuvers requiring advanced technology for ship officers. In the berthing operation, ship officers have to control the ship’s motion taking the influence of external forces into consideration, and get the ship to a shore accurately. When the ship officers maneuver the berthing operation using small crafts, it is difficult to control the crafts’ motion because small crafts are susceptible to external forces such as wind. Ship officers are carried out berthing operation based on their experiences. So, it is necessary to develop a system to support berthing operation that allows the ship officers to maneuver without relying on their experiences. We propose a system consisting of three processes. In the first step, the system plans ship maneuvering from a initial position to a berthing point. In the second step, ship officers maneuver according to the plan. In the third step, the system predicts the future position, course, speed at specific points considering external forces. It notifies ship officers of the course and speed obtained from the prediction. In order to make predictions at specific points, it is necessary to carry out simulations of berthing operation based on maneuvering motion model of small crafts. In our research, we measured maneuvering motion of small crafts in actual seas to aim a support system of berthing operation. Our objective is to model maneuvering motion of small crafts simply in berthing operation using measured results in actual seas and to verify problems of support system of berthing operation.

抄録全体を表示

In recent years, researches on automatic driving techniques for improving the safety and comfort of automobiles are actively conducted, and there are few problems at Levels 2 and 3 compared to fully automatic operation. In the automatic operation of Level 2 and 3, it is assumed that the operation permission is returned to the driver in the event of an emergency, and in order to smoothly take over the operation, it is thought that the driver and the system need to know each other's situation. As a method of estimating the driver's condition and intention, it was found that driver's intention can be estimated as a result of examining the method using driving energy this time.

抄録全体を表示

Recently, in order to decrease the number of traffic accidents, various automotive safety technologies have been studied. As one of these technologies, Nipun et al. have proposed the autonomous frontal avoidance system, which avoids frontal obstacle by autonomous evasive steering. However, since the existing system considers only a forward obstacle, the ego vehicle collides with the road boundary under narrow road conditions. Therefore, in the previous study, Fujimori et al. proposed the autonomous frontal obstacle avoidance system considering the road boundary and showed its effectiveness by numerical simulation. In this paper, we execute an actual vehicle experiment of automatic avoidance. The results show the proposed trajectory updating method is effective.

抄録全体を表示

Human errors of train drivers may cause serious damage. Therefore, research on human error prevention has been conducted by many researchers. In this context, brain activity measurement of train drivers using Near-infrared Spectroscopy (NIRS) has been conducted to monitor the condition of train drivers. In this study, we developed a compact wireless wearable NIRS that can be used in natural environments. The wearable NIRS has been used to measure train driver’s brain activities in the field test. It was confirmed that brain activity measurement of the driver can be performed satisfactorily and applicable for real environment.

抄録全体を表示

The authors propose the idea of ultra-high-frequency rail network timetabling. In such a timetable, the scheduled trains will take very diverse routes on a given rail network to meet the diverse needs of the passengers and to enable ultra-high-frequency train operation. However, at junctions where two or more lines meet, the level crossing interference between different railway tracks will form the bottleneck for the realisation of such high train frequency. The typical example of this can be seen at crossovers between fast and slow lines on the quadruple track railway paired by use. To reduce such level crossing interference, the authors propose the simultaneous crossovers of two trains in both directions at crossover tracks, and the installation of multiple crossover tracks at one junction for realtime selection of the optimal route. In this paper, the authors present the detailed calculation of headways between trains at this kind of crossover tracks, which will form the basis of the authors’ future research into their ideas.

抄録全体を表示

In the process of rail transport scheduling (or planning), we focus on an operational rolling stock rostering problem. The objective is to minimize the number of executed maintenance, and the primary constraints are to cover all train trips for the next several days by rolling stock units and to satisfy daily and monthly maintenance constraints on them. However, no study in the literature has optimally solved a practical instance with such maintenance constraint. This paper provides a framework to solve a practical instance optimally in reasonable time by adopting a branch-and-price (or column generation combined with branch-and-bound) approach and by devising an efficient method to answer the column generation subproblem which appears repeatedly in branch-and-price.

抄録全体を表示

Energy-efficient driving is effective method of reducing energy consumption of railway system. However, that has not been investigated in detail at short headway situation. Here we show what driving technique is much better from energy consumption point of view. In the simulation, we examine a technique to drive a train in an energy efficient way when the preceding train is delayed departing station. The results show that it can suppress energy consumption less than or equal to regular running time situation.

抄録全体を表示

It is essential to monitor the conditions of railway assets to ensure railway safety. Low-cost monitoring systems are developed based on on-board sensing devices and global navigation satellite system (GNSS) data, and applied to real operations in regional railway. In the system, the sensing device is installed in an in-service vehicle to measure car-body vibrations. The diagnosis is performed by evaluating the track conditions based on the measured vibration data. We proposed a time-frequency analysis methods, Hilbert-Huang Transform (HHT) and Continuous Wavelet Transform (CWT) for detecting track faults. Results showed that HHT is suitable for evaluating track condition.

抄録全体を表示

When a ropeway carrier is travelling upward, it suddenly swings backward greatly while passing through a tower, and collided with the tower. One of the accident causes is pointed out to be wind gust. This paper provides simulation results of carrier swing behavior as wind gust acts from the front when the ropeway carrier passes through the tower upward. The main results obtained are as follows. (1) Regarding the action timing of wind gust, backward swing of the carrier becomes the largest when wind gust acts near the time of carrier entering the tower. (2) Wind velocity of wind gust to allowable swing angle when the carrier passes through the tower is 19.8m/s at the time of 9 people ride and 19.6m/s at empty vehicle. (3) Carrier swing behavior when damping ratio is increased is made clear in the case where wind gust acts when the carrier passes through the tower. (4) Proper damping ratio may reduce carrier swing when wind gust acts and improve safety agsinst wind gust when ropeway carrier passes through the tower. The future task is to study the best damping ratio in order to improve safety against wind gust when the carrier passes through the tower. It is expected that more safety measures will be taken to prevent the recurrence of the accident.

抄録全体を表示

Road surface displacement measurement is one of potential functions of vehicle on-board stereo vision, as it is important for both manually-driven and autonomous vehicles to improve ride comfort performance by preview suspension control. This paper proposes a novel method of preview road surface displacement estimation from stereo camera images for preview suspension control. This method is also valid even there is a change of the vehicle heading during driving with a processing frequency of over 30 Hz. The estimation accuracy of speedbump is verified on straight road in a testtrack, and the validity of the proposed road surface displacement estimation method is examined. And in the vibration control simulation of the active suspension, the control effectiveness is verified by the preview suspension control using the estimated road displacement.

抄録全体を表示

This research deals with the detailed analysis of tire cornering characteristics. At first, we assume the required elements to express the tire characteristics for vehicle dynamics. Based on the elements, we focus on the difference of the distribution of the contact pressure for the lateral direction between tire testing machine and vehicle. Using the pressure distribution, uniformity of tire for the direction of circumference is considered in the contact area of tire, because the uniformity has an influence on the tire characteristics. In addition, we measured the distribution of the contact pressure for each rib in order to clarify the influence of the load and air pressure. As the results, it is shown that the influence of the circumferential uniformity does not affect the load change. Furthermore, it is shown that the shape of the pressure distribution of the tire testing machine varies depending on load and air pressure. However, it is found that the shape of distribution for pressure on the vehicle doesn't change.

抄録全体を表示

This study deals with the vehicle dynamics of leaning tricycle. This vehicle has a camber angle on the turning inner side while turning like a motorcycle. In this research, first, the equation of motion of a tricycle with parallel links for front wheels is constructed. In this equation of motion, the four degrees of freedom of the lateral direction, the yaw direction, the roll direction, and the steering angle are taken into consideration. Using the equation, eigenvalue analysis was performed and the weave mode, wobble mode and capsize mode were reproduced such as motorcycles.

抄録全体を表示

In order to grasp the flow around a simple shape train model running in a tunnel section, we manufactured an experimental train model with a scale of 1/62 on which a comb of total pressure tubes was mounted. We propelled the train model by the model launcher at a speed of 110 to 150 km/h and measured the flow velocity around the train model. We obtained the time history waveform of the flow velocity variation and flow velocity distribution in the radial direction. We also estimated the local friction coefficient from the flow velocity distribution by the Clauser method. We confirmed that the local friction coefficient obtained in the tunnel section is equivalent to that in the open section when the flow velocity outside the boundary layer is used as the reference velocity in the train fixed coordinate system.

抄録全体を表示

A wheel/rail profile wear is a factor that affects the behavior of railway vehicles such as riding comfort, running stability, running safety and maintenance schedule. To predict wheel/rail profile wear theoretically with dynamic model of the vehicle-track systems, Wear coefficient or Wear index is necessary and these parameters are generally gained from laboratory test such as twin disk test. It is difficult to gain Wear coefficient or Wear index accurately from field data, because the wheel/rail contact conditions which decisive for wear have big variations. On the other hand, there are railway systems in which vehicles of the same type run on the dedicated track with the same operation pattern. In this case, there is possibility to generalize Wear coefficient or Wear index. In this study, we focus on this point, a large amount of wheel profiles from Tokaido Shinkansen, one of high-speed trains in Japan, was investigated. In this paper, wheel wear characteristics of coupled motion is pointed out and these wear characteristics are attempted to demonstrate from a view point of vehicle dynamics.

抄録全体を表示

There is a possibility that wheel wear leads to such problems as noise, lowering of running stability and impairment of ride-comfort. Therefore, it is essential to predict wheel wear in order to actualize running stability and running safety of railway vehicles. Previous studies on prediction of wheel wear progress have identified wear coefficient and conducted wheel wear tests with the use of twin desk and model wheelset. In wheel wear tests by equipment as described above, wheels run on roller rig. In this case, contact condition is different from the case that wheels run on roller in terms of creep, contact force and contact area. It is considered that contact condition of a wheel and a rail affects development of wheel wear Thus, in the case of wear test with twin desk and model wheelset, it is necessary to grasp differences of contact condition between the case wheels run on rail and the case wheels on roller rig. In this paper, from the view point of multi body dynamics, wheelset / roller rig analysis model is constructed. In this paper, from a view point of multi body dynamics, wheelset / roller rig analysis model is constructed in consideration of the contact geometry between wheel and rail. By conducting numerical analysis, differences of contact condition between the case wheels run on rail and the case wheels on roller rig are compared and examined.

抄録全体を表示

The friction force acts to the travelling pantograph head in horizontal direction due to sliding of the pantograph head and contact wire. This study proposes a 2-dimensiodal pantograph model that considers friction characteristics of the pantograph head based on the multi-body dynamics approach. Furthermore, a stability analysis method based on the complex eigenvalue analysis for the pantograph model is proposed. The equation of motion of the pantograph model is derived based on both the differential algebraic equation (DAE) and the linear dynamics equation (LDE). Results of the LDE-based stability analysis of pantograph models are shown. Then the obtained stability is validated based on the DAEbased time history response analysis of the pantograph models.

抄録全体を表示

Path planning is essential for the autonomous driving or advanced driver assistance systems. Efficiency and ride comfort of vehicles is achieved by path planning using smooth reference paths where there is no discontinuity. If we want to ensure the continuity at the connecting points of sequentially generated paths, it is necessary that the curvature at the endpoints of each paths can be specified. In this research, the method to generate such a smooth path is proposed. The proposed paths are composed of three clothoid curves, which have same length and are connected with no discontinuity of curvatures and tangent angles. It is shown that the proposed method can generate a path in at most a few iterations and that the path can be easily tracked by using curvature information. A discussion of preferable combinations of path generating method and path tracking method is also given.

抄録全体を表示

In recent years, the automobile industry has entered a historical turning point. Environmental problems such as global warming have attracted attention and electric vehicle (EVs) using an electric motor instead of a conventional internal combustion engine are attracting attention. However, electric vehicles have the disadvantage of short cruising range. The authors’ research group proposes Range Extension Autonomous Driving (READ) that extends the range by optimizing the velocity profile under the assumption that traffic signal information. It can be obtained from Intelligent Transport System (ITS). In a previous study of READ, only a single traffic signal was considered. However, considering the practical environment, multiple traffic signals should be considered. In this paper, we propose a method to realize velocity optimization which achieves minimization of total energy consumption by considering straight road with multiple traffic signals. The effectiveness of the proposed method is verified by simulations and experiments.

抄録全体を表示

Population of elderly people are growing in Japan and maintaining their independent living is an important issue. The number of mobility scooters, which supports short-distance locomotion of the elderly and help them maintain their independence, are increasing and becoming more common. However, traffic accidents involving mobility scooters are occurring and the accidents include fatal accidents. Therefore, we aim to construct a low-speed mobility system which secures safe locomotion of the elderly with an autonomous locomotion function installed in a mobility scooter. Mobility scooters can travel inside pedestrian space, because they are regarded as pedestrians. For autonomous locomotion in pedestrian space, safety which can be interpreted as no collisions with the surrounding pedestrians, is one of the most important factors to be considered. However, riding comfort and time required for locomotion are also important factors. In this research, we examined an autonomous motion planning method which improves comfort and smoothness of locomotion respectively while ensuring safety, mainly for mobility scooters used by elderly people. For improvement of comfort, we proposed a trajectory planning method which restricts vehicle behavior with large acceleration and jerk. For improvement of smoothness, we proposed a method which enables the vehicle to follow other pedestrians. Considering the two proposed methods, we constructed an autonomous motion planning method and evaluated the effectiveness with numerical simulation. The simulation results revealed that each proposed method increased riding comfort and smoothness of locomotion respectively without decrease in safety.

抄録全体を表示

Energy consumption and CO₂ emission are world-wide problems．In Japan，a project for reducing CO₂，called “ Energy ITS project ” has started from 2008 to 2012 by NEDO (New Energy and Industrial Technology Development Organization)． According to a previous study of Energy ITS project in NEDO，it has been proved that fuel efficiency improves by over 15 % due to reduced air resistance in platooning of three heavy-duty trucks at constant speed of 80 km/h and following distance of 4 m．However，when a lead vehicle generated minute fluctuation due to the road gradients or the influence of the surrounding vehicles during the platooning，the trailing vehicles follow the movement of a lead vehicle and minute acceleration and deceleration occurs．In this paper，we propose a method to control minute acceleration and deceleration of a trailing vehicle and the effectiveness of a proposal method is verified with simulations by incorporating it into the longitudinal control．We actualize to smooth acceleration and deceleration by introducing a sensitivity function for cognition of following vehicle distance error and suppressing minute acceleration and deceleration．

抄録全体を表示

Due to the declining the number of labors in depopulated areas in recent years, necessity for small mobility service equipped with automatic operation that anyone can use as a new transportation service is expected. However, when applying the automatic driving system to inexpensive small mobility, it is assumed that introducing an expensive invehicle sensor becomes an obstacle to popularization of small mobility services. In this research, we evaluate the situation in the limited area of the intersection using the image information of the fixed point camera installed near the traffic light and investigate whether it is possible to construct a collision accident prevention system during automatic driving by communicating with small mobility in a short distance.

抄録全体を表示

As a promising technology, Truck Platooning is expected to improve traffic safety, fuel efficiency and driver-lacking issue. However, it is necessary for us to investigate the social acceptance before large-scale application. A series of exterior Human Machine Interfaces (HMI) that aim to improve social acceptance and safety of peripheral drivers were proposed. In this paper, the effects of the exterior HMIs on driving behavior of peripheral drivers were then evaluated using Driving Simulator.

抄録全体を表示