U To locate vehicles precisely, Bosch has developed a motion and position sensor, which is based on signals from the Global Navigation Satellite System (GNSS). The satellites fly at a distance of 25,000 kilometers and at a speed of 4,000 meters per second. Their signals can also be read by modern navigation systems, but the accuracy of the signals is disturbed by the long signal path and various influences. Therefore normal navigation systems are not suitable for autonomous driving.
Data corrections for precise location determination
Bosch therefore uses correction data from various providers. With the help of a network of precisely measured reference stations on earth, these providers can correct the inaccuracies in the GNSS position information. The correction data gets into the car via a cloud or geostationary satellites. In addition to GNSS signals, the motion and position sensor receives further information from wheel speed sensors and the steering angle sensor. Coupled with highly intelligent software, the sensor then knows exactly where the vehicle is and where it is going.
System secured several times
If the system loses contact with the satellite, the software can maintain the position of the automated vehicle for a few seconds. The position of the vehicle is then calculated relatively from the last known absolute position information. If the GNSS signal is interrupted for a longer period and the position can no longer be determined using the motion and position sensor, the road signature from Bosch is available to the automated car. This is a map-based localization service based on the environment sensors of current and future vehicles. Video and radar sensors on board cars record stationary features on and next to roads, such as lane markings, traffic signs and crash barriers. These are then compared with highly accurate cloud-based maps and used for navigation.