Development Guide

Optical flow and LIDAR-Lite

This page shows you how to set up the PX4Flow and a LIDAR-Lite for position estimation in the INAV position estimator. A short video demonstrating a position hold can be seen here:

Hardware

The PX4Flow has to point towards the ground and can be connected using the I2C port on the pixhawk. For the connection of the LIDAR-Lite please refer to this page. For best performance make sure the PX4Flow is attached at a good position and is not exposed to vibration. (preferably on the down side of the quad-rotor).

Parameters

All the parameters can be changed in QGroundControl

  • SENS_EN_LL40LS Set to 1 to enable lidar-lite distance measurements
  • INAV_LIDAR_EST Set to 1 to enable altitude estimation based on distance measurements
  • INAV_FLOW_DIST_X and INAV_FLOW_DIST_Y These two values (in meters) are used for yaw compensation. The offset has to be measured according to the following figure: In the above example the offset of the PX4Flow (red dot) would have a negative X offset and a negative Y offset.
  • INAV_LIDAR_OFF Set a calibration offset for the lidar-lite in meters. The value will be added to the measured distance.

Advanced

For advanced usage/development the following parameters can be changed as well. Do NOT change them if you do not know what you are doing!

  • INAV_FLOW_W Sets the weight for the flow estimation/update
  • INAV_LIDAR_ERR Sets the threshold for altitude estimation/update in meters. If the correction term is bigger than this value, it will not be used for the update.