Quad makes crazy jump after touched down

[kohlerj]

@mfaessle Isn't it the source of this bounce back we discussed a few months ago

SOURCE

[mfaessle]

I don't remember, can you elaborate a bit what symptoms we are dealing with here?

[kohlerj]

When you land with the snapdragon providing the state estimate, everything goes well until you touched down at which point the state estimate is lost. Here we see that whichever the states was, if the state estimate is regained then a "hover" control command is sent. If you're closed to the ground then it will jump up again. Is that more or less understandable ?

[mfaessle]

I'm assuming that this is not necessarily related to touching the ground but what the state estimate is doing right after it was regained. It might be that the state estimate goes crazy for a bit after touching the ground and then being reinitialized, at least with the snapdragon. Since this is more of a conceptual thing on how one wants to treat this issue I'm proposing to following ideas:

1. Introduce a flag whether we allow to autopilot to switch back to hover after the state estimate is lost and then regained. If it is not allowed, the quad would just finish the emergency landing and then switch off. (But I would not always impose this behavior since for e.g. a motion capture system it makes sense to go back to hover)
2. Introduce a short timeout during which the quad is allowed to switch back to hover after the state estimate was lost and regained. This would allow to overcome short glitches as we might have with SVO which might be more desirable compared to the above solution.

Let me know what you think about those