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I've built a quadcopter using the Dji Wookong-M. As of a couple of weeks ago I have been able to get everything to work except for one small thing. When I throttle up the Drone tends to flip to the side. I have tested all the motors over and over again and I know that they are spinning the right direction and that I have the right props on the right motors. I tested on both grass and concrete but both times it flipped. It starts to flip once the throttle is past 50%. I don't know if it is catching or if something is off balance although I don't think this is the problem since the quadcopter tips different directions almost every time. If any one could tell me what is wrong I would appreciate it a lot since my project is due in 2 1/2 weeks.

Thanks in Advance

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    $\begingroup$ Without any data, anyone that answers will be guessing at what could be wrong. Can you provide any data? Pictures of your quadcopter, your test setup, data from the flight controller, etc. $\endgroup$ – Chuck May 10 '16 at 13:02
  • $\begingroup$ It might be that the input to the motors is saturating (the additional control input from disturbance rejection makes the total input occasionally exceed 100%) and that the saturated system is too unstable. $\endgroup$ – fibonatic May 11 '16 at 16:33
  • $\begingroup$ I am new to this. How would you suggest fixing this problem? $\endgroup$ – Ben May 12 '16 at 2:43
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Referencing my answer from https://robotics.stackexchange.com/a/12086/15014 ,

There are multiple possibilities for the flip of quadrotor.

  1. It can be because of incorrect prop directions (in X or + configuration, the diagonally opposite props must have same rotational direction and adjacent props must have opposite rotational direction; This is all about compensation of angular momentum).

  2. It can be because of a faulty ESC or improperly tuned ESC. There are several ways to tune ESCs properly. (Like this: https://librepilot.atlassian.net/wiki/display/LPDOC/ESC+Calibration )

  3. It can be an issue of PID tuning. (http://myfirstdrone.com/tutorials/how-to-tune-a-quadcopter/ https://oscarliang.com/quadcopter-pid-explained-tuning/ )

  4. IMU may not be calibrated properly and the EKF estimates may be wrong. (https://fpv-flightclub.com/quadcopter-flips-takeoff/ Accelerometer and Gyro orientation along with Compass need to be properly set up)

  5. (Rare) GPS functionality might be malfunctioning ending that up with GPS locks for inaccurate location estimates.

BTW, there are many forums that address this issue and simple Google search is ending up with results like:

https://oscarliang.com/quadcopter-flies-unstable-flips-troubleshoot/

http://diydrones.com/forum/topics/quadcopter-flips-on-liftoff

https://www.rcgroups.com/forums/showthread.php?2284434-My-x-quadcopter-flips-on-takeoff

Please consider mentioning what you have tried and what hasn't worked (otherwise this question is 'too broad' with many Google results popping up for same).

+1 for @Chuck 's comment:

Without any data, anyone that answers will be guessing at what could be wrong. Can you provide any data? Pictures of your quadcopter, your test setup, data from the flight controller, etc.

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