Current ADAS combines a number of technologies in order to operate. In essence each system comprises at least one sensor to monitor given parameters and relay necessary information which is then processed and analysed before, if required, sending a command either to give a sensory alert to the driver or to intervene or assist with the control of the vehicle, by braking or steering, for example. With some systems, and under some conditions, a combination of some or all of the above may occur.
Driver alerts may consist of nothing more than a flashing light – a stability or traction control system’s intervention can be so subtle that the driver might be unaware it’s doing anything at all without a tell-tale blinking light on the instrument panel. Other alerts are necessarily more overt: a parking sensor’s increasingly urgent chimes are today familiar to many drivers, while a forward collision warning system often combines escalating warning chimes with an illuminated dashboard alert and a haptic alert through the steering wheel.
Haptic alerts – vibrations through the steering wheel and/or seat – are also a common feature of lane departure warning systems. When the lane departure warning function is expanded to lane keeping assist, the system can intervene in the control of the car to move the vehicle back towards the centre of its intended lane. The automotive industry’s recent wholesale switch to electric power assisted steering (EPAS), which was adopted largely for fuel efficiency reasons, has equipped many cars with hardware that is ideally suited for ADAS functions that intervene with autonomous steering inputs. Self-parking functions and the latest traffic jam assist features that can control the vehicle for limited periods in slow-moving traffic have also been enabled by the advent of EPAS.
Autonomous braking interventions are facilitated by components that heralded the arrival of ADAS in the first place: the ABS control module and pump. Today’s stability control, autonomous emergency braking, adaptive cruise control and traffic jam assist functions, among others, make use of developments of ABS hardware that allow for precisely controlled braking interventions when required.
If necessary, engine output is controlled or modulated by one or more means. In the case of traction control and electronic stability control systems, which often require a relatively subtle limiting of torque, it can be done by suppressing the ignition spark or restricting the fuel flow via the fuel injection system. On later vehicles with electronically controlled ‘drive-by-wire’ throttles, torque can be modulated via the throttle control unit.
Cruise control and active cruise both require full control of the throttle mechanism, either via an actuator on the throttle cable itself or, again on later vehicles, through the drive-by-wire throttle control unit.
This article is part of the ‘What is ADAS?‘ series.