Advanced driver assistance systems (ADAS) are features that help the driver by braking in an emergency, keeping the car in its lane or holding a safe distance from the car in front. The driver still drives. ADAS helps; it does not take over.
The common features are easy to name. Automatic emergency braking brakes if a crash is about to happen. Lane keeping steers gently to stop the car drifting out of its lane. Adaptive cruise control holds a set distance from the car ahead, and slows or speeds up with it. A blind-spot alert warns if another vehicle is beside the car where the mirrors cannot show it.
Ordinary cruise control only holds a speed. Adaptive cruise control also watches the car ahead, which is why it needs sensors.
Consider a car on a highway near Delhi at 80 km/h. A truck ahead brakes hard. The camera and radar measure that the gap is closing quickly. The ADAS software warns the driver with a beep. If the driver does not react, it asks the braking system to stop the car. The brakes belong to the safety electronics of the car, which must act within milliseconds.
ADAS must get the balance right. If it misses a danger, a crash can happen. If it brakes for nothing, for example for a shadow on the road, the driver is frightened and may switch the feature off. Engineers spend a lot of time on this.
In India, many new cars, mostly the costlier models, now offer ADAS as a package. Indian roads are harder for it than highways in other countries, because of scooters, cattle and faded lane markings.
ADAS needs a computer, which is one of the car's electronic control units. Because a fault can cause a crash, its software must meet rules described under safety certification. Companies test it in simulation before it reaches a road. It uses digital maps for speed limits and HD maps for lane detail. It also listens to the driver monitoring system. Its warnings appear in the digital cockpit.
ADAS covers the lowest levels of autonomy, up to Level 2. At these levels the driver still drives. Carmakers buy it from suppliers. For scooters and motorcycles, a smaller form of it is called rider assistance.