This UDV compact research report describes part of an extensive research project and summarizes the first part of this two-part study focusing on takeover times and highly automated driving. Automated vehicles in which the driver can allow the vehicle to do all the work on certain parts of the trip and no longer has to monitor anything are currently being developed by many automotive manufacturers. When there are driving tasks that these highly automated vehicles can no longer handle, control must be returned to the driver. The driver must have sufficient time to take over manual control of the vehicle safely and easily. To find out the time required for the safe takeover of manual control by a driver, takeover scenarios and secondary tasks of varying complexity were developed and tested in a static driving simulator with 60 subjects aged from 20 to 76. An empirical study was designed and conducted to find out when full physical and cognitive control over a vehicle was re-established after a phase of highly automated driving. The effect of a driver being “out of the loop” was analysed, in particular. In some experimental conditions, the driver was thus completely uninvolved in the task of driving, and distracted by a secondary task, at the time of the takeover request. It should be noted here that the times were ascertained in a driving simulator and thus can only be understood as an approximation of the time required for a takeover in a real vehicle. However, more recent studies do indicate that times ascertained in a simulator correlate well with those in a real vehicle. It should also be emphasized that the takeover time alone cannot be an adequate measure of the quality of a takeover. The times must always be seen in connection with other measures of the quality of the takeover. This include the quality of the safety of the takeover and the fullness of the driver's awareness of the situation during the takeover. In order to be able to interpret the results correctly, it is necessary to know the definitions of the automation levels. According to Gasser et al. (2012), highly automated driving refers to functionality that involves the vehicle taking control of both longitudinal and lateral guidance for a certain period. The driver does not have to continuously monitor the situation. Instead, the driver must take over control again with a certain amount of time to spare when requested to do so. The aim of this study was to ascertain how much time there is to spare. Highly automated driving is thus clearly different from partially automated driving. In partially automated driving, the vehicle also takes control of longitudinal and lateral guidance, but the driver has to monitor the situation continuously and be able to take back control at any time. The next step up from highly automated driving is fully automated driving, in which the vehicle handles longitudinal and lateral guidance completely and continuously. The driver is no longer required as a fall-back option, since in the absence of a driver takeover the system can put the vehicle in a status in which the risk of an accident is minimized. (Author/publisher)
Abstract