Abstract
Through last years, all developed Advanced Driver Assistance Systems (ADAS), have been attempting to increase road safety and to reduce the number of traffic deaths and injuries all over the world, supporting users and enhancing safety to all drivers. This is the case of Forward Collision Warning systems (FCW) or Lane Departure Warning (LDW), alert systems aimed to give support to drivers when an obstacle is found inside vehicle trajectory, and when the vehicle is stepping over lane boundaries, respectively. Most work done regarding that matter, investigates obstacles like vehicles found in front of driver’s car, pedestrians, even cyclist, and finally, driver alertness and behaviour while driving.
However, there is limited knowledge of which modality, whether acoustic, haptic or visual, is more appropriate to warn and induce drivers to apply steering manoeuvres if necessary, and what characteristics should those warnings have to achieve maximum efficacy.
This paper presents a study, carried out in a closed test environment, using a simulator platform. The main goal of this study was to gather information regarding objective performance of users while driving and subjective user feelings. The object of study is a haptic acceleration pedal as a new warning channel.
Two main tests were carried out separately. The first test was performed with 30 participants, using haptic pedal as an alert system for a Frontal Collision Warning (FCW). The second test used the pedal as an alert complement of a Drowsiness Detection System (DDS), with 14 participants in different sleep conditions.
In the FCW test, the results demonstrated that haptic stimuli decrease reaction times, speed variation and also vehicle approach, in contrast with visual alarms. The best performance was achieved with vibration torques of 1.60 Nm, and in the frequency range between 5 and 10 Hz.
As a complement for a DDS, this device was valuated as a secure element with a great predilection upon visual and acoustic signals. A set of physiological variables were also recorded in order to correlate the effects of several warning strategies and driving performance. These results contribute to solve the key dilemma of how to balance the efficacy of a warning signal with user acceptance
Keywords: ADAS, Safety, Warning Strategies, HMI