Manual

51
7.11 Proper ultrasonic coverage
The single most important requirement for the system to work well is to have
proper ultrasonic coverage
Each sensor has an ultrasonic beam of ~90 degrees. Outside of that range, the
emitting power and sensitivity drops quite rapidly. From the left, right, or back of
the ultrasonic sensor, the signal is highly attenuated. Thus, it is crucial to provide
proper ultrasonic coverage for the area where the robot will be moving.
- It is also very important to provide proper ultrasonic coverage to the stationary
beacons when the map is being formed.
Mobile beacon (“hedgehog” or “hedge”) is designed to be placed
horizontally
- The mobile beacon has four horizontal and one vertical sensor, each covering its
own sector. Together, they cover 360 degrees horizontally and 180 degrees in the
upper hemisphere. The lower hemisphere is highly attenuated, so don’t expect
ultrasonic coverage in that area.
It is advised that the mobile beacon be placed as high as possible on the robot if
the stationary beacons are above the mobile beacon. This minimizes shadows
from other objects, people, etc.