Looking at ADAS hardware

ADAS refers to a host of different safety systems, designed to assist the driver in avoiding an impact. Our earlier blog explains the most popular ADAS equipment. Even so, these complex systems gather information from four main physical parts.

Ultrasonic sensors

These systems tend to be used as parking sensors. Yet, they are useful for ADAS, too. They identify close-range objects and emit short, ultrasonic pulses that are analysed, once received back again. Their limitations include a restricted working angle. Thanks to their position, they can also suffer impacts and internal corrosion. Overpainting with an excessive paint film thickness reduces their effectiveness, too.

Cameras

Automotive cameras recognise and classify objects. They share the same basic principles as domestic and professional digital cameras, with which we are all familiar. Light falls on a sensor containing light-sensitive diodes. More diodes equal a higher resolution. The resulting information is converted to electronic signals and processed by an electronic control unit (ECU).

Cameras adapt to different tasks and recognise colours, too. They have a wide scanning angle of up to 180 degrees. In addition, they possess a range of between 50 and 500 metres.

They are less dependable with a dirty lens, or when visibility is restricted by poor weather. While they can measure wide angles, they have to calculate all other information. Car manufacturers like them, because they are small and can be

positioned within the interior. Windscreen-mounted cameras are especially popular. Yet, some carmakers are fitting them outside the vehicle, inside a protective housing.

Light Detection and Ranging (LiDAR)

This is the only sensor that provides accurate 3D measurements (i.e. distance, position and height). It works by emitting and receiving a pulsed laser beam. Lidars tend to be used for close and medium-range monitoring of up to 200 metres, although Bosch introduced a long-range lidar for automotive use several years ago, which is being adopted.

Lidars cannot recognise colours and their ranges reduce in poor weather, or if the outer cover becomes dirty. Even so, they can be positioned virtually anywhere on the vehicle, including the roof. In terms of their lateral and vertical ranges, lidar's scope rests between that of cameras and radars.

Radio Detection and Ranging (radar)

Radars send out electromagnet waves (as opposed to laser) that are received back into the sensor. The car's distance from the object, plus the object's size and position are all calculated from the time, direction and intensity of those received signals. Automotive radars have typical ranges between 0.2 and 250 metres and a scan angle of up to 80 degrees.

Not only are radars weatherproof and reliable but they are also accurate. Being measurement devices, no calculations are required. Their limitations are few but they cannot distinguish colours and cannot recognise shapes accurately.

Processing power

The computing power that is needed for multiple ADAS systems to receive, calculate and act upon all of the data received quickly is quite awesome. While some vehicles can perform the necessary processing, newer vehicles with more sophisticated

ADAS systems require the car to have 4G and even 5G data transfer capabilities. The car, therefore, transmits its gathered information wirelessly to a cloud platform, which performs the necessary calculations before sending the information back.

Other systems boast vehicle-to-vehicle communications. An example of this is Volkswagen Group's Local Hazard Information technology, introduced in 2017. Using GPS data and real-time information from cars, such as data from light, rain, stability control and airbag trigger sensors, one car can send data to other vehicles nearby, warning them of impending safety issues ahead. The more cars that participate, the more reliable the information becomes. This is a central principle of 'swarm intelligence', which is becoming more popular as a means of improving road safety.

Calibration considerations

Cameras, radars and lidars require calibrating. This is needed when certain works are performed on the car, relating usually to the windscreen, steering and suspension systems. More advice on this will follow in a future blog.

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