We have developed a method to estimate driver distraction by mean of involuntary eye movement of the vestibulo-ocular reflex (VOR) and optokinetic response (OKR) by using a driving simulator. This paper presents a practical application of the method to the real vehicle situation. The main concern was whether we can measure the eye movement of VOR and OKR caused by the road surface vibration in the situation. The experiments were conducted with participants sitting on the passenger seat for safety reasons. The results have shown that our method can be applied for evaluating cognitive distraction not only in a driving simulator but also in actual vehicles.

View full abstract

Innovation of fuel injection technology are necessary for lower emission and higher thermal efficiency of diesel engines. The effects of the geometry of injector nozzles on cavitation flows in the nozzles and discharged liquid jets have to be understood well, since the liquid jet and spray characteristics affect diesel combustion largely. In this study the effects of the inlet edge radius of injector nozzles on cavitation and liquid jet are quantitatively investigated by the visualization of two-dimensional nozzles with various inlet radii. As a result, we found that round inlet edge nozzles results in a thin cavitations,small cavitation clouds shed with a high frequency,and small liquid jet angle

View full abstract

Since the sudden acceleration (SA) accidents in the 1980’s, unintended acceleration has been an accelerator pedal operation mistake without a definitive solution. Recent advanced driver assistance system (ADAS) technologies are hoped to save victims from this kind of accident, but their effectiveness is limited. Drivers who have caused this kind of accident have stated that they pressed the brake pedal. An investigation of pedal operation by citizen drivers showed a characteristic action that could be the cause of the accident. This characteristic is also hoped to be an effective method to detect the accelerator pedal operation mistake and prevent unintended acceleration accidents.

View full abstract

In this study, knocking over a wide range of engine speeds was visualized using an optically acssessible engine. In addition, knock under a high compression ratio and supercharged, lean combustion was investigated. The results revealed that under high-speed knock, the flame propagation velocity declined when low-temperature oxidation reactions occurred. Subsequently, autoignition began locally and expanded gradually. Eventually, it was observed that a highly brilliant autoignited flame appeared and propagated through the unburned end gas at a high speed of approximately 1700-1800 m/s. This suggests that high-speed knock causes “developing detonation” in which combustion proceeds at a supersonic speed while pressure waves and the reaction front mutually interact. It was also found that strong knock occurred under supercharged, ultra-lean conditions (Compression Ratio: CR=14, Equivalence Ratio: Φ =0.5, Intake Pressure: P_in = 140 kPa). In addition, the application of exhaust gas recirculation markedly reduced strong pressure oscillations.

View full abstract

In this paper, a novel method is proposed to estimate the driving styles of other drivers based on a driving risk feature. This new feature is proposed using a dynamic potential field method wherein the distribution changes depending on the relative number of adjacent vehicles. A more appropriate description of driving risk is obtained compared to other indices. The proposed feature dramatically improves the accuracy of estimating the driving style. To estimate the driving styles, this study considers a problem of the fundamental model under a scenario wherein the target vehicle follows the preceding vehicle. The proposed estimation method is validated through experimental results.

View full abstract