Abstract
The common causes of traffic accidents include humans, equipment, weather, and road conditions. According to the statistics of Taiwan National Freeway Bureau, improper driving, including "improper lane changing" and "ignoring the state of front vehicle," is the main cause of traffic accidents. In other words, human (driver) is the most critical factor of traffic accidents. In order to compensate for the limitations of driver's abilities, the Advanced Driver Assistance System (ADAS) has been developed rapidly. The purpose of such a system is to help the driver receive information more rapidly and make decisions more accurately. However, a larger amount of information may be beyond the limit of human information processing, resulting in increased processing time and incorrect judgments. Thus, the purpose of this study is to investigate the effect of warning timing of driving assistance system on driving performance and safety, as well as analyzing the relationship between driver’s gender and decisions made. Through the corresponding improvements that help clearly remind the drivers, traffic accidents can be reduced effectively. In this study, Unity 3D was used to simulate vehicle operations on a highway in which the vehicle on the left-side lane plans to change lane and drive in front of the participant, so as to analyze how the warning timing of driving assistance system may influence the driving behavior. Twenty participants (10 males and 10 females) ranging from 20 to 26 years old who drive on the highway at least once a week or drive for 3 to 4 days continuously for at least one time in a month and with the driving experience of more than two years were recruited. Besides, their scores of Driving Anger Sale have to be between 41 and 53 (out of 70) for excluding those who are too conservative and too risky. Each participant was asked to perform a series of tasks without warning system as his/her baseline, and then perform three sessions of tasks with the warning system in which the warning timing is set at 2.5 seconds, 3.0 seconds, and 3.5 seconds prior to the potential collision respectively. The three sessions were arranged randomly to reduce the effect of learning and fatigue. Each participant needs to complete four sessions of tasks in total, with the NASA-TLX survey conducted after each session and followed by a 5-minute rest. The experimenter will define and calculate the success rate of task execution, error counts, and reaction time through using C# program to collect the range of brake, accelerator pedal range, and the absolute coordinates of the two cars during the experiment. After that, the effects of warning timing and driver’s gender on the correct rate of task execution, error counts, reaction time, buffer time (the duration from the moment that drivers take the reaction to the potential collision), and workload were evaluated by Two-Way ANOVA (Analysis of Variance).In other words, it was observed whether male and female drivers have each’s recommended warning timing. The results showed that there is no significant difference between the drivers' success rate of task execution at different timing of warning. The difference among drivers could be the main factor to affect the drivers' stability. The timing of warning will affect the driver’s degree of trust toward the system, and hence affect the driving behavior. More specifically, the drivers had the longest buffer time and the lowest workload at the warning timing which is set at 3.5 seconds prior to the potential collision. Male participants' success rate of task execution is higher than that of female participants, which indicates that males tend to have better stability while driving. However, females had longer buffer time, which allows them to reach the safe status more quickly before the potential collision. This hence given them more time to prepare for other unexpected situations. Further, there is no difference in workload between males and females: So, the driver’s gender could not be a main factor affecting the drivers' workload. Overall, the driver’s perceived trust toward the driving assistance system is a key factor for judging whether the system can assist drivers effectively. Hence, while designing a driving assistance system, it is necessary to focus on whether the timing of warning matches the drivers' expectation without conflict. In this way, a higher degree of trust in the driving assistance system can effectively help drivers reduce the time required for dealing with unexpected traffic conditions, resulting in enhanced quality of decision making and safety. In addition, females tend to trust and depend on the system more than males do, which contributes to the better performance. Future improvement of the design should be focused on how to increase the males' degree of trust toward the system, so as to enhance the males' driving performance as well.