paparazzi-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Paparazzi-devel] Vibration issues (?) on a quadrotor


From: Prof. Dr.-Ing. Heinrich Warmers
Subject: Re: [Paparazzi-devel] Vibration issues (?) on a quadrotor
Date: Wed, 15 Feb 2012 16:42:52 +0100
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; de-DE; rv:1.4) Gecko/20030619 Netscape/7.1 (ax)

Hi,
a vibration level of 20% full scale of the rate sensor  is  normal.
The best way is to damp vibrations and to balance the propeller   together with  with the  motor rotors.
You can try rubber screws   like on this page: https://www.mikrocontroller.com/index.php?main_page=index&cPath=77&zenid=f3cc9c70489e257d4d4e04552f0e1343
If the damping is to soft the quadcopter will became unstable.
Is your motor mounting, your frame, wiring and the PCBs  fix?
Can you sense  the vibrations  with  your hands if you hold the quadcopter?

Heinrich Warmers


Loic Drumettaz schrieb:
Hello, 

I have tried without success to fly my quadrotor in RC_CLIMB mode. Firstly, I had some problems with the altitude measured from the baro: i found out that the BMP085 mounted on the LISA M is sensitive to sunlight! I protected the sensor with foam and the altitude measurement is now OK. 

After this, i still didn't manage to use correctly RC_CLIMB mode: I found that the vertical speed (ins_zd) and accelerations (ins_zdd) are wrong.Vertical speed "zd" is varying from 3 to 5 m/s with the quad hovering.... And the acceleration "zdd" oscillates from -10 to 30 m/s² !!

Now, i guess that these vertical speed and acceleration errors comes from the accelerometers used in the ins kalman filter. In that case, i have several questions:

- What level of vibration/ noise of accelerometers is acceptable on a quad hovering? I have around +/- 7m/s²
- I have mounted the Lisa M on gel pads (http://www.rtom.com/moongel.htm), balanced the propellers, what else can be done to minimize vibrations on a quadrotor? Are there other things to pay attention?
- In case the vibrations can't be reduced, is it possible to tune the Kalman filter in the INS ? I have seen that the filtering is done in vff_float.c. In this file, the parameter ACCEL_NOISE is equal to 0.5: are there any chance to improve the filtering results by tuning this parameter?
- The vertical filter VFF can be turned off by removing the flag USE_VFF? What would be the consequences of such tuning? in other words, how ins_zd and ins_zdd are then calculated?
- I also updated aspirin.c file, in order to use +/-16 G range on the accelerometers. 
- Any suggestions to fix this problem?

Thanks for helping. I have started to describe the block diagrams of the rotorcraft vertical control loops, in order to add them to the paparazzi wiki. So I hope to contribute myself to the paparazzi project soon!

Regards
Loïc



_______________________________________________ Paparazzi-devel mailing list address@hidden https://lists.nongnu.org/mailman/listinfo/paparazzi-devel

reply via email to

[Prev in Thread] Current Thread [Next in Thread]