Two consecutive crashes with a S500

Hi, our S500 drone suffered a bad crash while flying in offboard mode. When we tried to diagnose the issue by flying in position control mode only, the drone crashed again and was destroyed.

  1. Offboard control:
  2. Position control only:

Click here to go to the Google drive folder containing the logs

Crash #1 (during offboard mode) might be blamed on our ROS control code. Therefore we repeated tests in position control mode only and suffered Crash #2, which ruled out errors in ROS control code. What is common in both crashes is many primary EKF changed [012] (filter fault) -> [012] messages. Visually, both crashes appeared to be due to the motors slowing down dramatically midflight.

A later flight test with an identically setup vehicle was safe and successful in both offboard and position control modes.

  1. Frame, propulsion: Holybro S500
  2. Autopilot: Pixhawk 4
  3. GPS: MRobotics M8N
  4. Companion computer: Jetson Nano

Any help in diagnosing these crashes are greatly appreciated! Crash #2 was very alarming as it happened during regular position control mode, on a vehicle whose setup has been working fine for the past year.

You first link has a logging start of 18:43
The second 14-04-2022 18:36
DId you reverse them?
Nonetheless, you had a bad crash, then like 7 minutes later you flew it again?
After bad crash you need to take it back to the shop and give it a complete checkout.
Just because the motors spin does not mean all it well.
For me the second crash would be expected.

First flight:
The drone went out of offboard mode and switched to stabilized; the throttle stick was at 0 → thrust = 0 → freefall

2nd flight:
The rear-left rotor failed (output 1 goes to max, drone rolls left and pitches back). Maybe the ESC lost sync?