K-Team Koala 2.5, Руководство пользователя

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Koala 2.5 User Manual Rev 1.1 13
4 IN DEPTH LOOK
4.1 Ultrasonic sensors
Nine sensors are placed around the robot and are positioned and
numbered as shown in figure below. These sensors are transceivers,
meaning that they can emit and receive pulses.
The ultrasonic sensors are powered by a 85 Vpp source. The nominal
frequency of these transducers is 40kHz +/- 1kHz.
The returned value is the distance to the object in centimeters, with a
tolerance of +/-2cm. Measuring range is from 25 to 250cm.
If the obstacle distance is smaller than 25cm, the Koala will return a
value of 0. If no obstacle is seen in the 250cm range, then the value
will be set to 1000. Finally, when disabled, the sensor will always
return 2000.
Each sensor can be disabled in order to get higher refresh rate for a
particular one (or group). One sensor measure takes 20ms. All 9
sensors need 180ms to be read.
If the auto mode is enabled for the US sensor, every time all enabled
sensor are refreshed, the dsPIC will print the value on the Pico-ITX
serial port (every 180ms if all enabled, every 20ms if only one sensor
enabled). This can be useful for application using the US sensors for
obstacle avoidance. If all sensors are disabled and the auto mode is
still active, no message will appear.
For more details about the ultrasonic sensor, please have a look at
the 400PT12B datasheet from Prowave.