H520 crash - ST16s freeze error

[airwojtas]

Hello, I would like to describe unpleasent situation which happened to me last weekend, just to warn you. I was flying a mapping mission with my H520 and everything was fine untill RTL and landing stage. As the drone is descending, I always pause the auto-mode and land the drone myself, as I can do it more gently. But this time something weird occured. Let me mention one thing that pisses me off about ST16s with DataPilot and its optimization - its a ********, as all the buttons tend to "freeze" if the video signal from E90 is low. This happens when the drone is too far away or too close (due to antennas direction). So, this time the drone was close to me (about 5 meters horizontally and 10 meters vertically), I tapped on the screen to pause the mission and the yellow slider showed up to confirm pausing. And this is the critical moment - I dragged the slider but with no response, as the slider freezed. So i tried to slide again (the screen was still freezed) and just after third slide the drone started to flyaway with 10m/s speed at the approx. 5-10 meters altitude, hitting the nearest tree and stuck in the upper branches. Fortunatelly, I managed to bring down the drone and tell nothing was broken. Unfortunatelly, there is no telemetry logs on the ST16s and I am not able to download logs from the H520 directly (I even tried do it via Mission Planner but the acces is denied). So what actually happened? One point to mention is that just after the crash I noticed on my ST16s screen (map screen) the new waypoint - "Go to location". I think that when the ST16s was "freezed" during landing and I tried to confirm pausing by dragging the slider, the ST16s read one of this dragging as the "tap" which was interpreted as "Go to location" command and last slide as the confirmation of "Are you sure you want to go to pointed location?" instead of "Do you want to pause?" The problem is that none of this command was showed up and everyting was executed as the ST16s was freezed. The second problem is that when the drone was hanging on the tree, the motors were not spinning untill I touch the drone - it just literally "woke up" and started the motors when I tried to bring it down. I could not disarm the motors - I tried red button in manual/angle/RTL mode but there were notifications "crash detected - can not disarm motors" - its not a joke. So I had to turn it off via the main button on the drone canopy which was not easy but somehow I did it. All in all, the drone is doing fine and I flied it today with no noticable changes in behaviour. Crash pic related. Cheers.

 

[arruntus]

What an adventure, it's a good thing the bird is still alive and well

You mentioned several interesting points to keep in mind:

• When it is too close or too far away, video reception problems freeze the ST16S -> it has never happened to me, being "far away" is more difficult to calculate the distance, but being "close", when you land, is always close and it has never happened to me. Which of the two antennas? The directional or the omnidirectional?
• Possible problem when pausing the mission -> we will have to test if it happens to us
• Landing in manual mode -> Highly recommended to avoid a rough landing, I haven't let it land in a long time just because in an update it was hitting the ground too hard. I don't know if it's been corrected.
• There is no telemetry -> this is the problem with the checkbox "save the telemetry only at the end of the flight" or something like that, as the flight has not finished, it not saved it? We must always have "always save the telemetry" activated?
  
• In the tree and without moving the engines turned off, but when you touched it, it started again by themselves? -> This can be a very severe error because the drone has to be disarmed themselves after a short period of inactivity, especially when the engines have stopped. Didn't they say in an update that for safety reasons the engine stop button stopped them even the drone was in the air?

What version are you using? Do you have everything updated? It's to know if we're dragging errors from previous versions or is something that happens in the last one.

Many things to keep in mind, thank you for sharing. And congratulations, nothing's broken

P.D.: correct mistakes, how bad English I have