A simulator evaluation of different forms of intelligent cruise control
report
Intelligent Cruise Controls (ICCs) are currently in development and will become commercially available within a few years. An ICC is an in-vehicle system that partially takes over the longitudinal driving task: it regulates a vehicle's speed and it is also capable of maintaining a proper following distance behind a lead car. Combining an ICC with a communication system from the roadside to the vehicle offers the possibility to obtain in-carnformation about relevant conditions on the road ahead. An ICC could even adjust automatically to that situation without intervention of the driver.
This report describes an experiment which was carried out in the TNO driving simulator to compare driving behaviour under ICC combined with several forms of in-vehicle information. The information which was sent to the vehicle was concerned with local speed limits and their rationale. The ICCs studied varied in the way this information was used: informative (leaving it to the driver whether to adjust his speed) or intervening (i.e. making the ICC automatically obey the speed limit). Also the way in which the information was presented to drivers was varied: in addition to a basic configuration, visual, acoustic, or haptic feedback could be given. Driving with one specific system configuration, subjects were confronted with a number of critical scenarios.
The behavioral measurements taken were related to the two modes of ICC, i.e. the regulation of one's own speed and the regulation of following distance. As expected, an ICC results in a reduced proportion of small time headways. With regard to speed choice it was found that only the intervening systems results in a speed reduction on sections with a special speed limit. However, there seems to be a compensating mechanism in that actively reducing a driver's speed on a few limited sections makes him drive faster on other parts.
It also appeared that the combination of ICC with in-vehicle information resulted in a somewhat later braking reaction of the driver in situations the ICC could not cope with. Effects of feedback type were not found, possibly because of the redundancy of the in-vehicle information, or because the basic feedback configu-ration is sufficiently informative. In the current experiment, subjects had to keep their foot on the gas pedal to keep the ICC active; this was done both as a safety measure and to enable the use of haptic feedback by means of theans of the gas pedal. Several disadvantages of this approach were found: a considerable proportion of the subjects gave a negative judgement about this aspect and the results show that some difficulties occurred in the operation of the system. The conclusion is drawn that the combination of ICC with different forms of in-vehicle information appears to show specific effects on driver behaviour, not all of them being favourable. A number of suggestions for relevant further research is presented.
This report describes an experiment which was carried out in the TNO driving simulator to compare driving behaviour under ICC combined with several forms of in-vehicle information. The information which was sent to the vehicle was concerned with local speed limits and their rationale. The ICCs studied varied in the way this information was used: informative (leaving it to the driver whether to adjust his speed) or intervening (i.e. making the ICC automatically obey the speed limit). Also the way in which the information was presented to drivers was varied: in addition to a basic configuration, visual, acoustic, or haptic feedback could be given. Driving with one specific system configuration, subjects were confronted with a number of critical scenarios.
The behavioral measurements taken were related to the two modes of ICC, i.e. the regulation of one's own speed and the regulation of following distance. As expected, an ICC results in a reduced proportion of small time headways. With regard to speed choice it was found that only the intervening systems results in a speed reduction on sections with a special speed limit. However, there seems to be a compensating mechanism in that actively reducing a driver's speed on a few limited sections makes him drive faster on other parts.
It also appeared that the combination of ICC with in-vehicle information resulted in a somewhat later braking reaction of the driver in situations the ICC could not cope with. Effects of feedback type were not found, possibly because of the redundancy of the in-vehicle information, or because the basic feedback configu-ration is sufficiently informative. In the current experiment, subjects had to keep their foot on the gas pedal to keep the ICC active; this was done both as a safety measure and to enable the use of haptic feedback by means of theans of the gas pedal. Several disadvantages of this approach were found: a considerable proportion of the subjects gave a negative judgement about this aspect and the results show that some difficulties occurred in the operation of the system. The conclusion is drawn that the combination of ICC with different forms of in-vehicle information appears to show specific effects on driver behaviour, not all of them being favourable. A number of suggestions for relevant further research is presented.
TNO Identifier
7921
Publisher
TNO
Place of publication
Soesterberg
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