Under the microscope: the new sensors - Intelligent networking of eyes and ears

Nov 19, 2012
Highly sophisticated sensors and the necessary networked algorithms provide the foundation for innovative new functions. DISTRONIC PLUS with Steering Assist, BAS PLUS and PRE-SAFE® Brake all employ sensor fusion using the same stereo camera and multistage radar sensors.
Mercedes-Benz is making a major leap forward with the introduction of the Stereo Multi-Purpose Camera (SMPC), or stereo camera for short. Just like the Multi-Purpose Camera (MPC) fitted previously, it is positioned behind the windscreen in the vicinity of the rear-view mirror. It has an opening angle of 45° and is capable of three dimensional detection of crossing objects and pedestrians, and calculating their path. The camera's two "eyes" provide it with a three-dimensional view of the area up to around 50 metresin front of the vehicle, and it is able to monitor the overall situation ahead for a range of up to 500 metres. In this way, the new camera is able to provide data for processing by various systems.
Intelligent algorithms evaluate this information in order to detect and carry out spatial classification of both vehicles that are driving ahead, oncoming or crossing, as well as pedestrians and a variety of traffic signs within a large field of vision.
Whereas the stereo camera's lenses act as the car's eyes, the radar sensors are its ears, so to speak, and provide additional data. The system of radar sensors comprises two short-range radar sensors in the front bumper with a range of 30 m, opening angle 80°, which are complemented by a long-range radar sensor (range 200 m, opening angle 18°) including mid-range scan (60 m, 60°). The data from the camera and radars is amalgamated in a control unit in order to provide the system-specific data for the various functions.
Here is a summary of the sensors and cameras:
  • Radars:
    • 2 short-range radar sensors at the front (30 m, 80°)
    • 1 long-range radar sensor at the front (200 m, 18°)
      with mid-range detection (60 m, 60°)
    • 2 short-range radar sensors on the sides at the rear (30 m, 80°)
    • 1 multi-mode radar sensor at the rear (30 m, 80°
      and 80 m, 16°)
  • Stereo camera (Stereo Multi-Purpose Camera, SMPC) located behind the windscreen in the vicinity of the rear-view mirror (range 500 m, incl. 3D capability for approx. 50 m, 45°)
  • 12 ultrasonic sensors (4 each at the front / rear + 2 each on the left / right in the front and rear bumpers)
4 cameras as 360° camera system (1 each at the front in the radiator grille / at the rear in the boot handle recess / on the bottom of the exterior mirror housings, vertical approx. 130°, horizontal > 180°, resolution 1 megapixel (1280 - 800 px)
An extensive system of additional internal sensors is able to keep an eye on the current driving state and the driver's reactions. If the sensors detect a hazardous situation, they are able to feed the algorithms for all manner of assistance systems with data in order to provide just the right support for the specific situation.