  Interacting with an in-vehicle system through a central console is known to
induce visual and biomechanical distractions, thereby delaying the danger
recognition and response times of the driver and significantly increasing the
risk of an accident. To address this problem, various hand gestures have been
developed. Although such gestures can reduce visual demand, they are limited in
number, lack passive feedback, and can be vague and imprecise, difficult to
understand and remember, and culture-bound. To overcome these limitations, we
developed a novel on-wheel finger spreading gestural interface combined with a
head-up display (HUD) allowing the user to choose a menu displayed in the HUD
with a gesture. This interface displays audio and air conditioning functions on
the central console of a HUD and enables their control using a specific number
of fingers while keeping both hands on the steering wheel. We compared the
effectiveness of the newly proposed hybrid interface against a traditional
tactile interface for a central console using objective measurements and
subjective evaluations regarding both the vehicle and driver behaviour. A total
of 32 subjects were recruited to conduct experiments on a driving simulator
equipped with the proposed interface under various scenarios. The results
showed that the proposed interface was approximately 20% faster in emergency
response than the traditional interface, whereas its performance in maintaining
vehicle speed and lane was not significantly different from that of the
traditional one.
