Introduction of internal EGR (Exhaust Gas Recirculation) is effective for improving the efficiency of ICE (Internal Combustion Engine), though the combustion stability usually limits its maximum amount. In this study, we modelled the dynamics of the cycle-to-cycle variation of the HCCI(Homogeneous Charge Compression Ignition) combustion, designed a controller that actuates fuel injections based on the dynamics, and evaluated it on real engines. The experiment of the controller showed the improvement of the fuel efficiency and possibility of extending the limit of the Internal EGR amount.

View full abstract

In addition to the conventional three-way catalyst (TWC) for CO, NOx, and HC, a gasoline particulate filter (GPF) is now required for filtration of gasoline soot in the exhaust aftertreatment system of gasoline direct injection (GDI) engines. For the space reduction in the engine room especially of hybrid cars which is combined with both an internal combustion engine and a battery-powered electric motor, we need the aftertreatment system coupled with TWC and GPF. However, deposited soot inside the filter may degrade catalytic activity. In this study, by using a lattice Boltzmann method (LBM), we conducted numerical simulations of catalyzed GPF to discuss the effect of soot layer on the conversion rate of TWC. We investigated the effects of the inlet temperature and the filtration velocity on the catalyst performance. Results show that as the inlet temperature is higher or the filtration velocity is lower, the conversion rates of CO, HC and NO are enlarged. When the soot layer is formed on the surface of the filter wall, these conversion rates are all reduced. the filter. These findings would be important for determining the period of filter regeneration.

View full abstract

We proposed a method to detect the opening/closing timing of the needle valve of diesel injector by measuring the vibration occurred during the operation with an accelerometer attached to the injector-body surface. Simultaneous measurements of the vibration and needle lift were conducted on the injection rig test equipment. Obtained results show that by measuring vibrations due to the mechanical contacts of a control valve or a needle valve in a solenoid diesel injector using an accelerometer, it is possible to detect the typical timings of needle valve motion.

View full abstract

We developed a driving energy simulator to study fuel cell output control of a hybrid test train. The simulator takes into account that the powering and regenerating performance of the test train depends on the SOC of the battery. The simulator was validated by confirming that it matched the driving test data. And the running simulation was carried out on a 15 km virtual route to show the efficiency and fuel consumption of the fuel cell.

View full abstract

When a drone is used to suspend and transport a load, the residual vibration that occurs when the drone stops is a problem. In this report, residual vibration is suppressed by elimination of the natural frequency component from the apparent external force, which considers the effects of non-linearity and damping. Numerical simulations and experiments have verified the effectiveness of this method for a suspended load of a multi-rotor drone.

View full abstract

A comfortable gearshift operation feeling is created by designing suitable gearshift sound for feedback to gearshift operation by paddle shifting, etc. In addition, the acceleration feeling was improved by designing gearshift sound for each gearshift stage, taking into account changes in the sound environment during acceleration driving. In this study, we created a gearshift operation feeling by sensitive balance design of geashift sound, gearshift shock and gearshift operation force.

View full abstract

Based on the need to improve quietness in the automotive industry associated with the spread of xEVs, we are developing laminated sound-absorbing materials that combine non-woven fabrics and foam materials. In this study, we calculated the sound absorption characteristics of a large number of lamination patterns using a homogenization method, and attempted to show material design guidelines by combining them with machine learning.

View full abstract

In this paper, the application of participation factor focusing on response at seat point for vibration evaluation of motorcycle frame in the early stage of development is described. Using extended participation factor called partial participation factor, which is an index showing the importance of vibration of specific parts or specific positions, major vibration modes are efficiently screened, and design change proposals are evaluated. In addition, the effects of these design changes are validated.

View full abstract

First of all, the definition of “Unit Mode” is a smallest unit component mode which has only one loop and cannot be decomposed any further. The resonance frequency of an unit mode is almost the same as that of whole system. An unit mode is a disassembly of eigenmodes of each part, and eigenmodes are obtained by assembling the unit modes. The energy correlated with the response of interest on unit modal coordinates is called “Power Flow”. By visualizing this, it is possible to draw a mode path diagram that shows vibration transmissions from the excitation point to the evaluation point. The path can be changed by shifting the eigenvalues. This paper introduces the concept of power flow and its application to vibration transmitted through the vehicle body.

View full abstract

In this paper, we propose a system that immediately informs a driver that he/she is pressing the accelerator pedal by means of a tactile vibration of the pedal. An experiment has been conducted with a driving simulator to investigate whether the pedal vibration system is effective in preventing pedal misapplication accidents and whether it is accepted to drivers. We induced pedal misapplications on a driving simulator and observed reactions of experiment participants. As a result, it was found that the pedal vibration system allowed drivers to notice pedal misapplication more quickly and to correct their foot position more rapidly.

View full abstract

For accident prevention and damage mitigation, this study mainly aims to understand the kinematic behavior and injury risk of children in collisions involving bicycles equipped with child seats through experiments. Rear-end collision tests were conducted between a car and a bicycle equipped with a child seat, and the effects of the seat belt and the headrest of the child seat were investigated. As results of the tests, there were risks of head injury when the child's head impacted the vehicle, the adult occupant, or the road surface. It was clarified that the headrests have a large effect on head injuries.

View full abstract

Impact SEA(ISEA) is a method to evaluate impact performance based on energy propagation. ISEA is used for the design of impact structures considering dynamic progressive buckling. In this paper, from the load-stroke diagrams used in vehicle body design, crash members are designed via the ISEA model and verified by FEM analysis that presents the development and validation of a design procedure using ISEA.

View full abstract

To enhance a driving experience, we focused on the driver's perceived sense of vehicular control, such as a sense of unity in driving. This study explores the relationship between the perception and vehicle characteristics or driver's attributes. In the experiment, participants were divided into three groups by their frequency of driving and performed some tasks on a driving simulator under conditions of delayed visual response, followed by a sensory evaluation questionnaire. The results show that visual response delay and individual driving frequency affect the formation of a sense of unity in driving.

View full abstract

A purpose of this study is to model ocular movement for stabilization with eyes and is to enable an evaluation about visibility due to the instability of eyes based on the model. Relations of visual acuity with retinal slip have been formulated in this paper. The dynamic visual acuity and the ocular movement of a participant seated on a 6-axes motion base have been measured simultaneously under whole-body vibration. As the result, the relation of the dynamic acuity with the retinal slip under the random input ( acceleration of the 6-axes motion base floor : ±0.5 m/s2 , ±1.0 m/s2 ) is according to V = V0 + 0.35 * S / (14.6 + S), where V is the dynamic visual acuity, V0 is the static visual acuity and S is the ratio of the visual target image on the retina beyond the central fovea range.

View full abstract

The framing effect is a phenomenon in which a change in the way the conditions are presented can significantly change the decision-making process, even if the presented conditions are objectively equivalent. It has been reported that negative framing tends to lead to stronger motivation. The purpose of this study is to examine the alerts that promotes safe driving. We investigated the effects of pre-driving and in-driving alerts on driving behavior. As a result, it was confirmed that alerts using negative frames, rather than positive frames, before driving and in the pause-situation could promote more cautious driving behavior.

View full abstract

Our previous research showed that it is important to project a visual target on fovea centralis stably for good dynamic visual acuity while riding in a car. In this research, to enable a numerical evaluation about dynamic visual acuity in a car, we propose a new single eye movement model based on physiological knowledge about eye movement. Our eye movement model has three characteristics as follows: (i) to stabilize eye motion by feedforward controllers using head motions, (ii) to decrease a retinal slip by feedback controller using the difference between a future position of visual target and current eye position, (iii) to estimate model parameters by regression equation of variance of head rotational angular velocity. And we show effectiveness of our proposed model by validation using the comparison between numerical result and experimental result of eye movement.

View full abstract

This research aimed to mitigate injuries caused by pedal misapplication accidents involving elderly drivers through the traffic accident analysis. The results revealed that, compared to younger drivers, elderly drivers had a higher proportion of pedal misapplication accidents in the following situations: in parking lots, with two or more collision marks on their own vehicles, during reversals, and with impacts to pedestrians or objects. Additionally, the impacted pedestrians tended to result in more serious injuries. Therefore, the development and widespread adoption of the acceleration control system for pedal error, which can effectively operate in such situations and mitigate injuries, are necessary.

View full abstract

Automobile exhaust emission has a serious impact on the environment. Driver models are currently used to predict the amount of CO2 emitted from vehicles, but the current models are inadequate as they do not capture the real road traffic environment. So, it is necessary to clarify the effects of traffic environments on driving operation under real-world driving conditions. In this study, how the driver’s accelerator operation, which has a large impact on CO2 emission behavior, was analyzed. Actual driving experiments using hybrid vehicles on multiple routes on public roads and highways were conducted in the Tokyo metropolitan area, and various data on traffic environments were collected and analyzed. To conduct the analysis, a driving model of a hybrid vehicle were created and which information about the traffic environment influences the driver’s driving operation were examined. Then, a multiple regression model to predict the amount of accelerator operation by the driver was created based on this information. In order to improve the accuracy of the model, a modified version of the model that takes into account the driver’s reaction time and the decision to accelerate off was developed. Finally, the created models were fitted to test data on general roads and highways to verify their accuracy and to analyze the magnitude of the influence of each traffic environment.

View full abstract