In recent years, engine development lead time has tended to be shortened. In order to deal with the shortened lead time, a MBD (Model Based Development) tool specialized for predicting piston ring performance was developed. The developed MBD tool enables to predict oil consumption, blow-by, and friction force on various piston ring specifications. In particular, for the oil consumption prediction model, statistical methods and experimental coefficients obtained by oil visualization in a glass cylinder were applied to reduce the calculation time. The high predictive accuracy of the model was verified on various engines, and significant reduction in calculation time was verified by comparing the developed tool with CFD (Computational Fluid Dynamics).

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The study of changing combination of motor/generator and transmission is actively conducted to improve the specific electric consumption of BEV. In this study, OpenModelica model provided by TRAMI was used to predict the specific electric consumption in both steady run and WLTC cycle with changing maximum motor speed, transmission system, and number of gear speed. Sensitivity analysis was also conducted to examine the factors that affect the efficiency improvement of electric vehicles. As a result, it was quantitatively found that i) WLTC ranking does not necessarily accord with steady one, ii) the ring gear output is good when using planetary gear system and iii) CVT shows high mechanical efficiency by keeping low input speed and wide ratio-coverage and the optimization of shift map will be required, and iv) a combination of 2 motor and multi-speed is the best in specific electric consumption.

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This study examines the quantification of roll feeling, the sensation felt by a driver during a turn. Traditionally evaluated subjectively, this study records the exact moments expert drivers feel it to establish a test mode. To include pitch behavior, vehicle movements are translated into changes in the driver's gaze on a forward-looking plane. By analyzing the linearity of gaze changes at the start of a turn and the extent of downward gaze movement, the roll feeling is quantitatively evaluated.

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This study analyzes the impact of vertical suspension friction on vehicle planar dynamics. The friction component reduces the roll angle gain relative to steering. Furthermore, it was found that, in roll understeer design, it increases the vehicle response gain at low frequencies and small steering angles, and thus acts in the direction of reduced vehicle stability in the on-centre region. A new evaluation method that can reveal minute differences in vehicle response was proposed by conducting slow-ramp input tests and using the driving trajectory as the evaluation target.

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This study addresses the development of a forward-looking road friction estimation system for snowy regions in winter, where road surface conditions fluctuate significantly. Specifically, we investigated a method for estimating road friction based on environmental information in snowy regions during the winter. Therefore, we compared the contact-based road friction coefficients with non-contact environmental sensors on a proving ground, including surfaces such as dry pavements, packed snow, and ice. The study identified a correlation between the road friction coefficient and the infrared absorption rate (reflective intensity) measured by LiDAR and RGB camera. Additionally, we confirmed that road surface brightness and friction coefficient exhibit a correlation based on LiDAR and RGB camera measurements. By classifying various road conditions using environmental data gathered on a proving ground, our findings suggest that environmental information can be effectively used to estimate road surface friction characteristics ahead of a vehicle.

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We describe the design procedure for the vibration isolating support system with leaf springs for the electric compressor. In a battery electric vehicle (BEV), the electric compressor is directly attached to a car body frame due to the absence of an engine. Car body frames lack vibration isolating support parts such as engine mountings. Therefore, the vibration isolating support system for the electric compressor is essential. The electric compressor not only cools a cabin at high temperatures but also heats a cabin, an electric motor, and a battery at low temperatures. Rubbers used in conventional vibration isolating support systems stiffen at low temperatures and worsen the vibration isolating effect. However, metal leaf springs feature the flexibility over the wide range of temperatures and produce the consistent vibration isolation effect.

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This paper discusses guidelines for power plant structural design to enhance the sound quality of engine combustion noise. Based on the modal analysis, guidelines for enhancement of power plant vibration modes were derived to reduce half-order and odd-order vibration at the resonance frequency of a power plant combining a four-cylinder engine with a transmission. The validity of the proposed guidelines was verified through finite element analysis using a simplified structure simulating a power plant.

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This study analyzed Japanese accident data from 2022 to 2023 to estimate the crash rates of automatic transmission (AT) cars and older drivers using the quasi-induced exposure method. A conditional logistic regression analysis was performed on a paired sample consisting of 163328 responsible drivers and an equal number of non-responsible drivers. The findings indicated that AT cars were 0.91 times less likely to be involved in accidents on general roads and 0.63 times less likely on expressways compared to manual transmission (MT) cars. However, the crash rates for AT and MT cars showed minimal differences between younger and older drivers.

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This study proposes a method to reduce traffic accidents caused by distracted drivers by investigating the optimal deceleration intensity and initiation timing of gentle deceleration for alerting, differing from conventional systems such as FCW and AEB. Experiments with expert drivers revealed that a deceleration of over 0.075G redirects a distracted driver's attention, while under 0.125G is tolerable for following vehicles. Additionally, the reaction time for around 0.1G deceleration is mostly within 1.6 seconds. Therefore, it is effective to start gentle deceleration of 0.1G from TTC of 3.4 seconds to alert a distracted driver while considering the impact on the following vehicle.

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Switches equipped in the cockpit of automobiles require various tactile feedbacks depending on their purposes and vehicle models . Evaluation of tactile feedback has been conducted using adjectives. However, the relationship between psychological adjectives, such as “comfortable”, and physical characteristics had not been clarified. In this study, we used the evaluation grid method to structure Kansei, aiming to develop a quantitative model for the psychological aspects of the tactile feedback of switches. Specifically, through a 10-subject test, "comfortable" was found to consist of three factors. In addition, the subject tests confirmed that the factors were classified into two clusters and that the factors brought about different influence depending on the clusters.

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To address elderly driver crashes at stop sign intersections, we developed a driver evaluation system using DMS-based head movement analysis and driving scores. The system, integrated with a driving simulator, generated diagnostic reports to provide feedback on driving behavior. Among eight elderly drivers, driving scores increased by 9% on average after feedback, with a 40% longer checking time and reduced vehicle speed during confirmation. However, not all drivers showed similar improvements; drivers with reduced cognitive function or overconfidence demonstrated limited progress. These findings highlight the potential for short-term behavioral change and the need for tailored feedback strategies for individual drivers.

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Autonomous highway merging poses a unique challenge for achieving “High Driving Automation.” Currently, UN Regulation No. 157 assesses autonomous merging based on criteria for regular lane changes. This study investigates the necessity of distinct criteria for merging. Using a driving simulator, we analyzed driver behavior and acceptability, focusing on the impact of cut-in vehicles on the responding driver during merging versus lane changing scenarios. The results indicate significant differences in driver responses between the two maneuvers, supporting the establishment of specific criteria for merging. These findings have important implications for improving the safety and efficiency of autonomous vehicle systems.

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The analysis of the life cycle greenhouse gas emissions of various passenger vehicles and heavy-duty trucks indicated that hybrid electric vehicles powered by ethanol from sugar beet and hybrid electric trucks powered by synthetic diesel from wood had the lowest emissions. In addition, projections for future emissions indicated significant reductions, particularly for xEVs and vehicles powered by e-fuel. However, battery electric vehicles and trucks were found to have relatively higher emissions when powered by electricity from marginal sources. Therefore, it is desirable for powertrains powered by carbon-neutral fuels such as e-fuel, biofuels, and hydrogen to become the mainstream.

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The die coating film in hot stamping is damaged by the following processes. Al plating on the surface of the work piece adheres to the die surface. The adhered material reduces the clearance in the die and increases the surface pressure on the die during processing. The increased surface pressure and sliding load cause cracking and chipping of the coating. We have developed WC-Cr3C2-Ni-CaF₂ thermal spray coating that has both heat resistance and anti-adhesion properties. No adhesion to the Al plating of the work material was observed, and no cracking or chipping was observed in the coating. Improved PVD-CrAlN coating was developed to withstand high surface pressure by relieving residual stress. The damage to the coating was reduced in spite of increased adhesion of the work piece Al plating compared to the conventional PVD-CrAlN coating.

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This paper describes the negative effects of communication latency on the stability of teleoperated vehicles and proposes a stabilization method using model predictive control. This method is designed to expand the operational design domain of teleoperated driving systems, particularly to enhance drivability at high speeds. In this method, a controller can calculate optimal manipulated variables while considering communication latency. This is because it has a model of the controlled system that incorporates predicted communication latency. The proposed method is validated through testing in a digital twin and verified for robust stability against latency.

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In urban autonomous driving, it is necessary to accurately distinguish and recognize stationary structures such as buildings and vegetation near the road from moving objects such as vehicles and pedestrians. In this study, we developed a technology to accurately overlay LiDAR point clouds onto stationary structure point cloud maps by correcting temporal distortions in the LiDAR data and applying coordinate transformation using multiple landmarks such as poles. This technology enables reliable detection of moving objects.

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Research and development of automated driving technology has been actively conducted to solve various social issues. Autonomous driving systems struggle to handle unexpected situations, which is why remote driving is anticipated to serve as a backup in such scenarios. In a remote-controlled vehicle system, the pilot is affected by the lack of physical sensation and delays in the transmission of camera images. Therefore, it is essential to evaluate the driving characteristics and workload of a remote vehicle pilot. Few studies have been conducted on remote-controlled vehicle systems for high-speed. Then, this study aims to clarify the pilot's driving characteristics and subjective evaluation of driving under remote driving in a high-speed environment of 80 km/h by conducting evaluation experiments using a driving simulator.

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In this study, we used a headlight testing machine to investigate the correlation between high beam and low beam and irradiation characteristics of various LED headlights and halogen headlights, based on various inspection standards for automotive headlights. It was found that when switching to low beam from high beam characteristics suitable for inspection standards, the irradiation direction and irradiation intensity differ depending on the type of LED. When a halogen lamp with appropriate irradiation characteristics was replaced with an LED, both the high beam and low beam irradiation directions failed to meet the inspection standards, but the irradiation intensity increased.

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In recent years, there is a demand for accurate reading of the Vehicle Identification Numbers (VIN) stamped on End-of-Life Vehicles (ELV) in order to manage which parts have been removed from each ELV. In this study, VIN reading software was developed to realize individual management of ELVs and their parts, and the verification and improvement of its accuracy were discussed.
To realize individual management of ELVs and their parts, we used AI-OCR to read VINs and verified the accuracy of the software. As a result, we were able to understand the characteristics of the software and text strings that are easily misrecognized. In the future, we plan to incorporate these obtained results into our reading software to further improve accuracy.

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Fuel spray injected into diesel engine cylinder develops with entraining ambient air. Air entrainment flow surrounding the spray side boundary interferes with that of adjacent sprays. And the spray interferes with piston wall and develops along the wall surface. Then the spray interferes with the adjacent sprays developing along the wall surface similarly. In this study, the effect of each interference on combustion was analyzed by using engine combustion CFD simulation.

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A method to quantitatively evaluate the deposit effects of fuels and lubricants in various usage environments of direct-injection gasoline engines has been investigated. TG-DTA and Autoclave were selected as test methods that could simulate all the operating environments in the engine and calculate the deposit generation rate. The experimental test conditions that can quantitatively generate deposit for the selected evaluation method are reported.

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Effects of concavities formed by piston skirt profile or pattern coating on the piston skirt on the friction reduction in an internal combustion engine were investigated by calculation. Calculations of oil film were carried out under assumption of insufficient oil quantity at the concave based on experimental results. Friction loss increased when there was no oil in the concave. It was found that when there was oil in a part of the concave, depending on the concave types, the friction loss was lower compared with the condition where the concave was completely filled with oil.

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A method for correcting the frequency response of fine wire thermocouples was applied for the first time to measure in-cylinder gas temperature. The study examined thermocouples subjected to FIB processing and those that were not. It was determined through frequency response theory that the necessary gain could be achieved and that a thermal inertia effect exists, indicating a required length for the processed section. Results from the actual engine implementation demonstrated the ability to accurately track temperature variations at 3000 rpm, confirming the effectiveness of this measurement technique.

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An asphalt road equivalent to N6 traffic volume was constructed on the Noda campus of the Tokyo University of Science. Coils were embedded for dynamic wireless power transfer in 2023. Regarding the variation during embedding, three identical small case-less coils were used, and a common embedding method was applied to evaluate the variation. However, despite fluctuations in the Q-value, the variations in efficiency, received power, and transmission current were minimal, and no significant differences were observed in either electrical or mechanical characteristics. Regarding high-power operation, the results indicate that operating under a current-limited load, rather than strictly adhering to the maximum efficiency load, offers significant advantages. A comprehensive evaluation of the electrical and mechanical characteristics was conducted. The electrical characteristics are sufficient, with a Q-value of at least 288, efficiency of 94% to 96%, and power of 48.3 to 55.2 kW at 600 V equivalent. Next, with regard to the mechanical characteristics, the design exceeds the 10-year road design period, which is also sufficient for road durability. Regarding mechanical characteristics, the design lifespan exceeds 10 years for road applications. In the embedding of 12 coils, a balance between electrical and mechanical characteristics was achieved for all coils.

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The vibration response characteristics of the stator change depending on the constraint condition of the laminated core and the winding. In this study, a new method of modeling the winding, insulating paper, and varnish and using spring elements as constraints was investigated. By this method, it became possible to analyze the vibration effect of each specification change. The natural frequency error agreed with the actual machine within 4.5% accuracy in the second, third, fourth, fifth, and zero order annulus of two different varnish filling rates. It can be applied not only varnish but also other fixing methods.

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This study aims to investigate drivers' directional judgments and psychological aspects at intersections when using metaphor for route guidance of AR-HUD. In the VR experiment, experimental conditions were consisted of yaw and roll angles of the metaphors and the number of metaphors. Participants approached a left-turn intersection which was divided to three directions while experiencing various combinations of metaphor design of AR-HUD, and then asked to judge what direction the metaphor indicated. Experimental data were analyzed and evaluated in terms of reaction time and psychological aspects.

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This study focuses on drivers' visual behavior. It experimentally investigates the effect of the blind spots around the front pillars on driving at intersections using an immersive driving simulator. As a result, it was confirmed that visual behaviors, such as the driver's head-turning, increased with the enlargement of the blind spots. The effect was evaluated using a visibility score based on these visual behaviors.

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Previously, the comfort of seats on their own has been evaluated, but the overall comfort evaluation of the vehicle interior space has not been examined. Humans integrate multiple sensory inputs, a phenomenon known as the crossmodal effect. This study investigates how the crossmodal effect of tactile and visual information influences comfort evaluation. When different vehicle interiors were visually presented, it was revealed that the comfort of the same seat varies. The results suggest that the tactile evaluation of the seat is not always accurate. Moreover, visual information was found to influence comfort evaluations under more conditions than tactile information.

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