RangeFinders Setup Overview

There are many different kinds of rangefinders: Lidar (using laser or infra-red light to measure distance), Sonar (using ultrasonic sound), and Radar (using microwave RF). Some are analog, producing pulses whose timing represent the distance to an object, others are digital sending data streams over serial to UARTs, or I2C, or even via DroneCAN.

RangeFinders (Sonar or Lidar) can be used for Object Avoidance as well as altitude sensors for precision landing in Plane and Copter.


Object Avoidance features are new and should be used with caution.

Up to 10 Rangefinders can be used in the system (1 thru A). Object Avoidance can use a single 360 degree Lidar, or up to 9 unidirectional rangefinders: 8 arranged in a circle covering 45 degree wide segments, plus an upward facing rangefinder. And a downward facing rangefinder used for low altitude height above ground measurements.

Connecting and Configuring the Rangefinder


Note that if the type of rangefinder is set or changed, a reboot will be required.

  • Set the parameter PRXx_TYPE = 4 for each horizontal rangefinder(s) to use them as Proximity Sensors (For obstacle avoidance).

  • For Copter and Rover, up to 8 rangefinders may placed around the vehicle to provide 360 degree coverage, or a single 360 degree Lidar. But only one forward facing rangefinder is required for Object Avoidance.

  • If a rangefinder is oriented facing up, then it will be used in the Simple Object Avoidance operation as an upwards sensing proximity sensor in Copter LOITER, ALTHOLD, and POSHOLD modes.