Genya Abe

Trust in and use of automation: their dependence on occurrence patterns of malfunctions

The dynamics of trust in and use of automation are shown to depend on the occurrence patterns of malfunctions. Two experiments have been conducted as part of this study. The first experiment compared the effects of two typical occurrence patterns, continuous and discrete. The second experiment analyzed the effects of the combination of the two malfunction occurrence patterns. Several analyses were performed and the following findings were obtained. If continuous malfunctions occur, operator trust is reduced significantly, and eventually the operator does not rely on the automation, even under circumstances that are easy for the automation to handle. The longer the continuity, the longer this effect lasts. In contrast, discrete malfunctioning does not cause a significant decline in the operators level of trust. A single malfunction or a small number of discrete malfunctions causes that some operators not to rely on the automation when the operation is difficult for the automation. However, the level of trust returns quickly under normal operating conditions. As operators gradually experience more individual malfunctions, they appear to become less sensitive to the malfunctioning.

Effects of arousing attention on distracted driver's following behaviour under uncertainty

This paper proposes issuing alerts to arouse driver attention when the traffic situation ahead is uncertain. Here, “uncertain” means that there exist cues suggesting something is happening in traffic ahead, but it is unclear to the driver and the driver assistance system whether an emergency situation will really occur in the near future, because traffic ahead cannot be seen directly. In such a situation, the driver has to pay attention ahead to prepare a quick response in case an emergency occurs. An experiment with a high-fidelity driving simulator was conducted to investigate the effectiveness of an attention arousing system when the driver was distracted. The results showed that the attention arousing system contributed to increasing time headway (THW) to the lead vehicle, where THW is the headway distance divided by the host vehicle speed and is often used to evaluate the rear-end collision risk. Such safety compensating behaviour was observed not only under distracted conditions, but also under non-distracted conditions. However, the compensating behaviour was not excessive under non-distracted conditions. The attention arousing was effective to maintain safety when the lead vehicle decelerated rapidly. The reaction time was long when the drivers were performing a distracting task. However, because the drivers had increased THW beforehand when conducting the distracting secondary task, the delay in reaction did not worsen the situation.

Effective and Acceptable Forward Collision Warning Systems Based on Relationships Between Car-Following Behaviour and Reaction to Deceleration of Lead Vehicle

This study mainly forcused on unnecessary alarms for forward collision warning systems (FCWS) and two driving simulator experiments were conducted to investigate whether considering individual driving characteristics is reasonable for decreases in unnecessary alarms when determining alarm timing. The results indicate that if the average characteristics of car-following behaviour are taken into account when determining alarm timing, unnecessary alarms are not a problem except for drivers who tend to follow a lead vehicle with the short distance between vehicles. Alarm timing based on the particular characteristics of individual car-following behaviour thus has the potential to further decrease unnecessary alarms, independent of driving speed.

Effects of Missed Alarms on Driver's Response to a Collision Warning System According to Alarm Timings

By using a driving simulator, two kinds of alarm timing were compared to investigate how drivers respond to missed alarms regarding different alarm timings: (1) an alarm was given based on ordinary braking behaviour for the individual; alarm timing T, (2) an alarm was given by using an particular alarm trigger logic (Stopping Distance Algorithm) as a common timing for all drivers; alarm timing S. Alarm timing S was earlier than alarm timing T in this study. The results showed that compared to alarm timing T, alarm timing S induced earlier braking behaviour independent of degree to which an imminent collision was critical. However, effects of a missed alarm on braking behaviour may be mitigated by alarm timing T, compared to alarm timing S. Moreover, it is possible that effect of missed alarm on drivers trust may vary according to alarm timings and the number of experience of missed alarms.