The combustion characteristic timescale model by Kong et al. was applied to zero-dimensional chemical kinetics calculation with a detailed elementary reaction scheme in order to predict combustion processes under various operating conditions in a gasoline HCCI engine, and it has been shown that combustion processes as well as ignition timings can be predicted by means of this method. The effects of initial chemical species compositions on ignition timing were investigated by zero-dimensional chemical kinetics calculation, and the mechanism of ignition promotion due to CO was inferred on the basis of Kuwahara's contribution matrices.

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Studies were conducted on catalyst and emission control technologies with the aim of extending lean operation of gasoline direct injection engines for better fuel economy. A 99.5 % NOx purification efficiency was obtained with a potassium-based NOx trap catalyst by enhancement of gas diffusivity in the washcoat and also sulfur purge capability.Combined with HC reduction technologies such as a larger valve-overlapping during cold start catalyst warm-up and HC slip prevention control during NOx purge operation, a vehicle with this catalyst meets the Japanese SULEV regulation.

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Two motor hybrid system was designed with using original two output coaxial motor and the transmission unit was made experimentally. Motor- and system-characteristics were optimized to each other and these coaxial components were carefully combined and arranged in the unit so that the unit can handle 2.5L-gasoline engine while the length is less than 350mm.

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An in-wheel motor unit is positioned as a next-generation vehicle drive system that allows a larger passenger compartment, independent control of each wheel with high responsiveness and lateral vehicle travel. This paper will describe the configuration of a newly developed in-wheel motor unit that can be housed in a 15-inch wheel and provides sufficient output to power a small passenger car.

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We have developed a method for evaluating the risk levels of a driver's behaviors when passing through a non-signalized intersection without the right of way by using data on the subject vehicle's position and speed and the driver's eye-movement and pedal operation. We calculated the lowest speeds for various types of vehicles approaching from either the right or left that may collide with the subject vehicle. These values are useful for identifying the types of vehicles crossing a driver's path that pose a danger to the driver and for improving a driver's awareness of safe driving behaviors.

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Simulator experiments were conducted to evaluate the effects of alcohol intoxication on task performance. Nineteen graduate school students participated in the experiments. Their measured performance in a simple reaction time task showed no significant differences between sober and intoxicated conditions. On the other hand, their measured performance in cognitive multiple tasks performed on the simulator, Multi-Attribute Task Battery (MATB), showed significant differences among the intoxicated conditions. The scores of an MATB tracking task in particular indicated a noticeable decline in performance. These results suggest that the effects of alcohol tended to appear in a multi-task situation and that the tracking task, resembling vehicle lane-keeping, was easily affected by alcohol intoxication.

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Driver assistance for cognition and judgment is effective for reducing traffic accidents. However,environment recognition by the sensor is not perfect in the real world. False and missing alarms may cause dangerous situations or disuse of the system by losing driver's trust. We propose a warning method corresponding to recognition reliability of the sensor in order to suppress reduction of the trust from the standpoint of risk engineering. In this research, evaluation experiments using a driving simulator were conducted for a lane change assist system. Effectiveness of the proposed warning method was verified when using the recognition sensor with some errors.

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