We were flying today the Arducopter 4.1 version and in one of the flights, we constantly got the message “Emergency: Yaw imbalance 10%” with the value changing to 11% and 12%. After reading the documentation, we figure it out that this means that the yaw action is getting saturated, and that the higher the imbalance the closer the vehicle gets to not having more control power for the yaw action. However, it seems to us that the warning was triggered a long way before reaching the threshold set in ATC_RAT_YAW_IMAX=0.5. Checking at the motors, it seems that the quadcopter still has control energy, since the difference between the motors PWM is not higher than 100us:
Please find the log below:
In summary, we were expecting the warning with an imbalance of 50%. By the way, the new Firmware is growing on us so far.