Manual

254
11.15. 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.