takeoff issue with the new flow deck 2.0 + HL controller

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wydmynd
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takeoff issue with the new flow deck 2.0 + HL controller

Post by wydmynd » Tue Feb 05, 2019 9:37 am

Hello
I had a CF with the new flow deck 2.0 and it will not take off properly. mostly going sideways and just ... crazy behaviour.
I am using high level controller (mellinger). CF2.0 with flow deck 1.0 and same code takes off properly.
I also found that putting the CF on a stand about 80mm from the ground will allow the CF to takeoff properly.
it may be that the new Z sensor behaves differently for small distances ("blind spot") so it may require adjustments to the controller.
I'm using crazyflie_ros but I assume that it is not a ROS related issue.

Is there a suggestion what parameters I can tweak to compensate for this behaviour?

much thanks

wydmynd
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Re: takeoff issue with the new flow deck 2.0 + HL controller

Post by wydmynd » Sun Feb 10, 2019 10:00 am

currently have a "stand" that is a workaround for the problem. even 50mm from the ground allows for stable takeoff.
52441267-e3ad9180-2b28-11e9-84c1-ec320f558770.png

arnaud
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Re: takeoff issue with the new flow deck 2.0 + HL controller

Post by arnaud » Mon Feb 11, 2019 4:10 pm

If you are using the position controller for take-off, this is something that I have seed before. It is surprising that you are seeing more problem with flowV2 though, might give more clue about what is happening.

See this post for my current assumption about what is happening: viewtopic.php?f=11&t=2652&p=16038#p16038

If you take-off with velocity control and then switch ON position control, you should get better performance. Ideally I would like to find what is happening exactly to fix it. Maybe disabling or reducing the trust in flow data when bellow some height could help.

wydmynd
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Re: takeoff issue with the new flow deck 2.0 + HL controller

Post by wydmynd » Tue Feb 26, 2019 2:50 pm

thank you for the reply. I have been managing with the "contraption" for now, but 1 in 8 takeoffs results in crash.
Do you know of an example of transferring from hover commands for takeoff to high level commands for hovering/flight?
I know that if high level controller is not enabled, drone will drop if no command is sent for 0.5 sec or so.
I attempted this order of events -

1) enable high level, set stabilizer to EKF, reset kalman to 0,0,0 (to avoid issues with position controller)
2) send /hover command in for loop
3) send goto command

drone crashes after step 2

any example or reference will be welcome!!
thanks

arnaud
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Re: takeoff issue with the new flow deck 2.0 + HL controller

Post by arnaud » Mon Mar 04, 2019 2:16 pm

I have never tried to enable the high-level commander mid flight. What I can understand from your description is that sending the Goto command crashes the Crazyflie.

- How des the crash looks like? (ie. is it a flip, just droppint, wild oscillation, ....?)
- How far is the goto command? I would send a goto to the current estimated or wanted position, to get the high level controller a way to get a hand on the situation and then when everything is stable I would start sending goto to point farther away.

whoenig
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Re: takeoff issue with the new flow deck 2.0 + HL controller

Post by whoenig » Tue Mar 05, 2019 3:52 am

There is currently no good way to switch from low-level mode to high-level mode (however, one can switch from high-level to low-level). I am working on firmware changes to allow graceful switches between these modes.

wydmynd
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Re: takeoff issue with the new flow deck 2.0 + HL controller

Post by wydmynd » Tue Mar 05, 2019 9:30 am

thanks for the replies. Goto command was for less than 50cm away.
I will try some variations and report back.

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