Motors slowly gain speed in STABILIZE mode

ArduCopter Copter 3.1
1

Hi,

I had a crash recently, and after the crash this problem happened.
After I arm in STABILIZE mode, put a little bit throttle, the motors all start to spin. But then one may hear the pitch becomes higher and higher, which means the motors spin faster and faster, while the throttle remains the same.
I tried to find out the cause, then I found

  1. Every motor does this and after ESC calibration, the problem still exists.
  2. the baro is giving very noise readings (-1m to 5m), but IMU and compass seem to be fine.
  3. VSI reading in ‘Gauges’ tab in Mission Planner fluctuates between -2 and 2.
  4. In ACRO mode the problem seems to be less serious, the motors reach top speed for the throttle position quickly.
  5. I am using APM1.4, hexacopter ‘+’ layout, 3DR ESCs.

So it there any answer to this or some ways to find out what it’s wrong?

Thanks in advance!
Alan

2

@AlanSixth,
Can you provide either tlogs or data flash logs to help us troubleshoot your problem?
Regards,
TCIII GM

3

Sure.
Please find the graph and log below.

Cheers,
Alan

4

This is normal behavior. This is the integrators winding up on the ground to try to overcome a slight attitude error (the ground isn’t perfectly level.) As soon as the copter is actually flying, it should unwind.

5

Cheers!

Yet another problem. My copter’s baro fluctuates within one or two meters when I test baro in CLI, but sometimes it suddenly goes up 5m or so and last very shortly. (APM1.4, even with baro covered by foam the problem still exists.) Does that mean the baro is in fault?

Cheers,
Alan

6

[quote=“AlanSixth”]Cheers!

Yet another problem. My copter’s baro fluctuates within one or two meters when I test baro in CLI, but sometimes it suddenly goes up 5m or so and last very shortly. (APM1.4, even with baro covered by foam the problem still exists.) Does that mean the baro is in fault?

Cheers,
Alan[/quote]
Yeah, the baro should be accurate to about 10cm in calm conditions.