Drone crash SITL


We currently test flight a drone in Gazebo environment. The drone use RTABMAP (SLAM) algorithm to locate itself. The position from the state estimate and the vision system were good, but we keep crashing the drone.

We use version 1.8.2 of the PX4 firmware & vision system to locate ourself.

The test case is a simple takeoff flight and maintain that altitude. After 45 seconds, the drone velocity Z estimate became terribly wrong and the drone is going down.

I check the hgt_test_ratio and pos_test_ratio, but everything looks fine. One thing I found suspect is the estimator time slip which increase a lot near the crash time. I do not understand what is this variable, so could anybody explain me the purpose of this data, could it be related to the repetitive crash?

Here’s a log file : https://review.px4.io/plot_app?log=6c6f6faf-5897-4dd6-9a25-69d0e569b2b3

Find out that the data are flat-lining has seen in the ECL EKF user guide for the GPS (https://docs.px4.io/master/en/advanced_config/tuning_the_ecl_ekf.html#determination-of-gps-data-loss)

I can’t figure out why since no flag were raised and vision_pose/pose data are still being sent…