ISA systems have to provide feedback to the driver in case of over-speed conditions, which
has to be appropriate and effective. As the current development of technology stands, there
are several technical options for the feedback methodology. However, not all of them can be
used in each and every motor vehicle (it depends on the engine, the propulsion type (hybrid),
the gearbox, etc.). Therefore, it is provided in the draft Delegated Regulation that vehicle
manufacturers can choose one of the following four feedback methodologies to base their ISA
systems on:
(1) the haptic feedback system which relies on the pedal restoring force:
–Driver’s foot will be gently pushed back in case of over-speed. It will help to reduce
driving speed and can be overridden by the driver.
(2) the speed control system which relies on engine management:
–Automatic reduction of the propulsion power independent of the position of drive’s
feet on the pedal, but that can also be overridden by the driver easily.
(3) the cascaded acoustic warning:
–1
st step: flash an optical signal
–2
nd step: after several seconds, if no reaction from the driver, the acoustic warning
will be activated
–If the driver ignores this combined feedback, both warnings will be timed-out.
(4) the cascaded vibration warning
–1
st step: flash an optical signal
–2
nd step: after several seconds, if no reaction from the driver, pedal will vibrate
–If the driver ignores this combined feedback, both warnings will be timed-out.
Despite the functional differences, ISA systems based on each of those four options are
considered equally safe and effective.