This is a getter function which returns the current bottom range of the drone. The default unit of measurement is centimeters.
This function uses the bottom range sensor to measure distance from the drone to the surface below the drone.
get_bottom_range(unit="<cm, in, mm, m>)"
unit: The unit of measurement that is chosen for the height distance. Available units are "m" (meter), "cm" (centimeter), "mm" (millimeter), or "in" (inch). If a parameter is not specified cm is chosen by default.
The current bottom range calculated by the bottom range sensor (cm default).