My quad running 2.9.1 (APM 2.0) seems hold altitude quite well in altitude hold mode and loiter. However, in altitude hold if I try and fly around it climbs. I tried guided mode and a point about 50m away and in the process of getting there it climbed about 20 meters. As soon as it gets there it realizes how high it is and descends. I've attached some log files showing this. I enter guided mode twice during this flight: the first time I have throttle accell PID's enabled, during the second try I disabled throttle accel PID's for altitude hold. The second time I would say it was worse. 

My APM 2.0 is mounted inside a stock case supplied by 3DR. My propellers are meticulously balanced. The logs include "RAW" but the Z Accel will show high because it was a little breezy. Anyways, I don't think vibration could be the problem because when I disable thr accel the problem gets worse. 

quad, 2216 motors, 11x5 carbon fiber props, all up weight about 44 ounces. 




Any ideas?


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  • Lucky you...whenever I go near this sticks in my small quad, it heads towards the ground, so much so you need to take the fingers off the sticks to let it recover it's height again..:-(

  • Developer

    replied over on the 2.9.1 thread.   It's vibes so set INS_MPU6K_FILTER to 20 and best to work on getting rid of the vibes in the frame or add more vibration dampening material between the frame and the APM2.x

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