Bitcraze Forums

I have been having takeoff issues with my crazyflie bolt drone. I've already made a post - viewtopic.php?f=5&t=5026&p=23020#p23020 to try and solve similar issues

The issue from before has only gotten worse - https://www.youtube.com/watch?v=FMuNeoyRv7k
The drone can no longer even takeoff. If you look at the video frame by frame, you can see two of the motors lag behind on startup (the right two) and then the back right motor catches up right before the crash.

It seems that the issue is that not all of the motors start at the same time. How can I fix this issue?

WHAT IVE DONE TO TRY AND FIX ISSUE:
1. Reflash ESC's with new parameters - Used "onewire" technique to lower the "Startup Power" and raise the "PPM Max Throttle"
2. Tune Position and Velocity PID - slightly tuned P value down

Any input helps. It is most likely a hardware issue because the drone has taken off very well in the past.

I ended up fixing the issue. The solution was to set motorpowerSet/enable = 1 and manually set and tune motorPowerSet/m1 to m4 to a decent value that cause the motors to spin up but not take off, and then disable motorPowerSet/enable and immediately go right into takeoff.

I'm guessing that initially, the when the motors weren't spinning, there was no back EMF, so syncing the speeds of the motors on takeoff was more of a guess. Somehow, when I first tested the drone, I was just getting lucky maybe? The takeoffs were very abrupt and now they are more smooth so I believe the issue is fixed.

When the motors are rotating before the first takeoff impulse, the motors are better suited to properly sync


https://youtu.be/yYUTH2q_bzE

I'm glad you found a solution!

There is a functionality to handle this called idle thrust. It is touched a bit in this thread.