Loiter and altitude hold vertical oscillation

Hi to every one.

I’ve build my first arducpoter, an hexa, with APM (1280) and IMU shield oil pan revH, GPS andmagnetometer. I’ve download on it the FW 2.42, it flies very well in stabilized with the stock PID.

I’ve issue in altitude hold and in loiter. When the two functions are active, the copter oscillate in vertical direction, of fewmeter, while the position in loiter is good with movement around the fixed point of about 1m.

I suppose that the problem is the baro sensor.

To check it, I place the copter on the ground with the APM power on, and ESC not powered on, to avoid the turbolences generates by the propellers. In this situationthe baro shows fluctuation of the altitude from zero to -250cm.

The plot and the log are attached. Is this behaviour normal for the baro? I expect a constant value, with some oscillation (in the order of cm)when the copter is on ground with motor off.

I trycover the hole on the baro with a little piece of sponge but without effect.

Any suggestion?

Thanks in advance.

Regards.

2011-09-18 09-41 3.log

Baro_log.tif

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Replies

  • Yesterday I setup the APM_Config.h to perform the in flight tuning of throttle_P. I'd lik to have a log of mode and to abtain that I activate the MODE log on the APM_Config.h but without success. 

    In the CLI setup, in the list of the enabled log don't appear the mode log, also if I enable all logs by CLI.

    Have you any aideas?

    The FW is the 0.42.

     

    Thanks

  • Developer

    That's normal... It's an amazing sensor, just not a magic sensor.

    You can play with throttle_P to tune that out somewhat though. Good luck.

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