Читать книгу Engineering Autonomous Vehicles and Robots - Shaoshan Liu - Страница 21

For mid-range obstacle detection, we can apply 77 GHz mmWave radar such that the planning and control module can make decisions when obstacles are detected. Similarly, sonars cover near-range obstacles and act as the very last line of defense; once sonars detect an obstacle, they directly signal the chassis to stop to minimize risks of an accident.

mmWave radar and sonar sensors can be combined and used for passive perception. By passive perception, we mean that when obstacles are detected, the raw data are not fed to the planning and control module for decision making. Instead, the raw data are directly sent to the chassis through the CAN bus for quick decision making. In this case, a simple decision module is implemented in the chassis to stop the vehicle when an obstacle is detected within a short range.

The main reason for this design is that when obstacles are detected in close range, we want to stop the vehicle as soon as possible instead of going through the complete decision pipeline. This is the best way to guarantee the safety of passengers as well as pedestrians.