Wrong Height using flowdeck

Firmware/software/electronics/mechanics
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Max_Kemmeren
Beginner
Posts: 26
Joined: Wed Jan 20, 2021 4:03 pm

Wrong Height using flowdeck

Post by Max_Kemmeren »

Dear all,

I experience a weird bug/problem with my crazyflie. I am using the flowdeck and experience the following. When sending setpoints via the python cflib (x,y,z,yawangle) the height varies between flights.

When I install a new battery on the crazyflie it follows my commands " perfectly" and so flies to the commanded heights and that can be seen in the state estimate logging. Then when I switch the drone off/on and run the exact same flight the crazyflie follows the commands but approximately 10/15 cm lower than the commanded height. Although the height by visual is way off the state estimate logging shows that the crazyflie thinks that it conducted the same flight and reached the correct altitude.

This bug happens everytime a new battery is installed. So first flight is correct, every flight afterwards is 10/15 cm lower. But the state estimate logging is the same everytime.

I hope my story is clear enough. Otherwise contact me on discord or arrange a meeting.
tobias
Bitcraze
Posts: 2168
Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: Wrong Height using flowdeck

Post by tobias »

That is a very weird behavior. Is it the same behavior if you don't restart the Crazyflie? It sounds like the ranging sensor (VL53L1x) is reporting the wrong height.
Max_Kemmeren
Beginner
Posts: 26
Joined: Wed Jan 20, 2021 4:03 pm

Re: Wrong Height using flowdeck

Post by Max_Kemmeren »

Dear Tobias,

I just tested what you said. And when I do not switch the cf on and off the height stays correct. But when switching the cf on and of without changing the battery the bug comes up. As I said it still thinks that it flies to the same altitude but in reality its not.

Greetings
Max
tobias
Bitcraze
Posts: 2168
Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: Wrong Height using flowdeck

Post by tobias »

I tried to reproduce it but couldn't. Could you share some more detailed instructions and possible if you have any script that you run.

My theory is that there is a large enough voltage dip to put the ranging sensor in a bad state during take off. Is it a particular battery that is problematic? Can you try the battery test in the console tab in the cfclient?
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