VOXL m500 crash

g-ferrando

Hello.

A week ago I had problem flying the m500 drone. I tried to fly it in different heights to look his stabization without GPS in an outdoors scene. We tried two heights. First one around 25 meters and the seocnd one around 50 meters. In the 50 meters, the drone had a problem and it landed with too much velocity and crash in the ground without having the chance to regain manual control. Before the falling, qgroundcontrol showed me two failsafes First it was "Critical: Manual control lost" and when we regained the manual control qgroundcontrol showed us "Critical: Failsafe enabled: no local position" and in that moment the drone start falling without having any chance to manual control.

Some information about the crash is that between 10:24 and 10:34 was the crash.

Files:

I have been looking the log file and there are a lot of questions:

Why does the drone start falling like it was landing when the parameter COM_POSCTL_NAVL was in "0" and it was not show in the log? That value means that the drone must change to Altitude Mode when position gps loss and it did not. Reference: https://docs.px4.io/v1.9.0/en/config/safety.html#position-gps-loss-failsafe
Why did the drone landed with too much velocity when the parameter(MPC_LAND_SPEED) is in 0.3 m/s? As you can see in the log file attach in Velocity graph velocity in Z is around 1 m/s and in the last stage of the land it increased to 10 m/s.
Why do the readings of current in Power graph show that there are two current peaks over 150A? And there are not any change in voltage or very little. One of them is very near when the crash happened, can it be responsible?
The log file show me that there was a land. I think it is a failsafe, but in real time qgroundcontrol did not show me that it triggered land mode. Why did the drone make a land and did not notify?
Moreover, the log file show me that readings between barometer and gps altitude in Altitude Estimated graph have a lot of difference like 150 meters, why? Is it bad calibration?
Finally, it is quite abnormal that temperatures from barometer and accel are too low in Temperature graph. It started with a normal data and it lowed.

Thank you for your response,

Gonzalo

Chad Sweet

Hi Gonzolo,

When you say without GPS, do you mean VIO? 50m seems a little high for robust performance.

There is a troubleshooting document here you can refer to for how to debug

Definitely be ready for manual control at any moment if this is a new environment

g-ferrando

Yes, I mean VIO and we were very carefully when we did it. Can you answer any of the questions I made? For example, position gps loss failsafe was not activated properly, because it did a land mode.
Thank you for your quick response Chad,
Gonzalo

g-ferrando

Hello,
Is there any chance to answer the questions I did?
thank you
Gonzalo

g-ferrando

Hello,
This is third time I do this, because the questions I did are a very important issue and my company and I want to solve what happened during the flight. So if you have any answer to the questions I did 27 days ago please respond them.
Gonzalo