Effects of Different Alarm Methods of Minimum Risk Maneuver on Drivers of Following Vehicles in Automatic Driving

Abstract: In recent years, the development of autonomous driving technology has been promoted all over the world from the viewpoint of safety and convenience. Autonomous vehicles are required to be equipped with Minimum Risk Maneuver (MRM), a function that automatically decelerates and stops while sounding a warning when the system determines that the driving behavior cannot be transferred to the driver. Although MRM protects the safety of the driver's own vehicle, the safety and security of surrounding vehicles must also be protected in order that autonomous vehicles are to be accepted by society. The development of MRMs that allow drivers to drive stress-free and with peace of mind is required. Therefore, the purpose of this study is to investigate the influence on the following drivers by the presence or absence of Alert Notification to the surroundings by using a Driving Simulator (DS) from questionnaires and motion data.As an experiment, autonomous car equipped with MRM was driving at 100 km/h on the first lane of a highway with a speed limit of 100 km/h and a road width of 3.5 m. followed the vehicle with a headway time of 2 seconds. Participants in the experiment were eight men (21.8 years ± 1.1 years old) who had a first-class driver's license for ordinary vehicles.In the experimental scene, After the Participant follow the Autonomous vehicle with a headway time of about 2 seconds, the MRM is activated and the self-driving car decelerates. This experiment was conducted under a total of 10 conditions, consisting of 5 conditions of 2.0 m/s2, 3.0 m/s2, 4.0 m/s2, 5.0 m/s2, and 6.0 m/s2, and the presence or absence of Alert Notification before deceleration. A horn was used as the notification, and the preceding vehicle continued to sound the horn while decelerating and turned on the hazard lamps.As a result, in the subjective evaluation questionnaire for the presence or absence of Alert Notification, significant differences were found at the 5 % significance level in the items of danger when the vehicle ahead braked and sense of anxiety when the vehicle ahead braked. In the comparison of the amount of brake application at different deceleration levels, significant differences were found at the 5 % level between deceleration levels of 2.0 m/s2 and 4.0 m/s2 and between deceleration levels of 2.0 m/s2 and 5.0 m/s2 in the case of no Alert Notification, but no significant differences were found when alert notification was provided. Significant differences were found in the subjective evaluation questionnaire, suggesting that the presence of Alert Notification can reduce the driver's subjective sense of danger and anxiety. In addition, the results also suggest that the presence of an ambient alert may allow the driver to brake with more time to spare.In the future, I am considering investigating the effect of the difference in Alert Notification method of the surrounding alert notification on the following driver.

Keywords: Minimum Risk Maneuver, Automatic Driving, Reminder Alarm, Stress

DOI: 10.54941/ahfe1003244

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