An Automated Vehicle Must Never Be Blind
Published on : Monday 10-02-2020
Bosch is filling the sensor gap and has started the development of a long-range lidar sensor for automated driving, writes Joern Ebberg.
Automated driving stands and falls with environment recognition. Only if it knows exactly, and at all times, what is going on around it can a self-driving vehicle choose the right, and above all safe, driving strategy. Bosch uses various in-house developed technologies for surround sensing, including ultrasonic, radar, and video. Now, Bosch is filling the sensor gap and has started the development of a long-range lidar sensor for automated driving.
The need for lidar, radar, ultrasonic, and video sensors
Only the parallel deployment of four sensor principles ensures that automated driving will offer maximum safety when it is rolled out. This has been confirmed by Bosch analyses, where developers investigated all use cases of automated driving functions – from highway assist to fully automated driving in cities. As an innovation leader in sensor technology for driver assistance systems and automated driving, Bosch can draw on its sensor expertise and systems know-how in the fields of radar, video and ultrasonic technology when developing the lidar. Furthermore, the company can ensure that all sensor technologies dovetail with each other.
Lidar sensor: In lidar systems, the sensor emits laser pulses and captures the laser light that is scattered back. The system then calculates distances based on the measured time it takes for the light to bounce back. Lidar offers very high resolution with a long range and a wide field of vision. As a result, the laser-based distance measurement tool can reliably detect even non-metallic objects at a great distance, such as rocks on the road. This means there is plenty of time to initiate driving manoeuvres such as braking or swerving.
Radar sensor: Bosch’s radar sensors provide important 360-degree information about their surroundings within a distance of up to 250 metres for automated vehicles. A radar sensor’s main task is to detect objects and to measure their speed and position relative to the movement of the vehicle. Furthermore, Bosch radar sensors send frequency-modulated radar waves measuring between 76 and 77 GHz via a transmitting antenna. These waves are reflected by objects in front of the vehicle. The relative speed and distance of objects are measured using the Doppler Effect and the delay generated by the frequency shifts between the emitted and received signal. Comparing the amplitude and phase of the measured radar signals makes it possible to draw a conclusion about the position of the object.
Ultrasonic sensors: Ultrasonic sensors are needed in automated driving, primarily for close- range environment recognition of up to 6 metres and at low speeds, such as during parking. The sensors employ the sonar technique, which bats, for example, also use in navigation. They emit short ultrasound signals that are reflected by obstacles. The echoes are registered by the sensors and analysed by a central control unit.
Video sensor: The latest version of Bosch’s front camera combines image-processing algorithms with AI methods. In congested urban traffic, it can for example recognise and classify partially obscured or crossing vehicles, pedestrians, and cyclists quickly and reliably. This allows the vehicle to trigger a warning or emergency braking.
Four eyes see more than two
For example, if a motorcycle approaches an automated vehicle at high speed at a junction, lidar is needed in addition to camera and radar to ensure the reliable sensing of the two-wheeler. In this instance, radar can struggle to detect the bike’s narrow silhouette and plastic fairings. Moreover, a camera can always be dazzled by harsh light falling on it. As such, there is a need for radar, camera, ultrasonic, and lidar, with the different technologies complementing each other perfectly and delivering reliable information in every driving situation.
Joern Ebberg is Spokesperson for Automotive Technology (Mobility Solutions – powertrain, diesel and gasoline systems, electromobility, air quality), at Bosch. The Bosch Group is a leading global supplier of technology and services.
