Wibbly wobbly...

Post Reply
Cheezey
Posts: 25
Joined: Tue Apr 08, 2014 11:38 pm

Wibbly wobbly...

Post by Cheezey »

I just got a MultiWii board (http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=27033) and set up a quad with 1130kv motors and 20amp Multistar ESCs. Before, it would lift a few inches off the ground, wobble, and tip over. Now I turned on a 42Hz low pass filter for the gyro and managed to get it a few feet off the ground, wobbling like crazy, until it went to the side and crashed. Is there any way to stop the wobbling and make it easier to fly? I have Angle and HeadFree on, but it still is impossible for a total beginner like me.

(I might not be able to test out suggestions for a little while because I lost the motor mounting screws in tall grass.)

waltr
Posts: 733
Joined: Wed Jan 22, 2014 3:21 pm
Location: Near Philadelphia, Pennsyvania, USA

Re: Wibbly wobbly...

Post by waltr »

Since the motor screws come out re-check that they are all properly tightened.
This may be caused by excessive vibration in the motors/props (and further indicated by a slight improvement in stability with the gryo LPF).
All the motors/props need to be balanced so there is very little vibration as seen in MultiWii Config sensor graph.
In addition the PIDs probably require some tuning but not until any vibration issue are resolved.
Once you are ready to tune the PIDs see this video:
http://www.youtube.com/watch?v=YNzqTGEl2xQ

Andy7
Posts: 129
Joined: Fri Dec 28, 2012 5:09 pm
Location: Oxford, UK
Contact:

Re: Wibbly wobbly...

Post by Andy7 »

Re your motor mounting screws.
Reducing your vibrations is the key to keeping all your screws. But I also put a drop of loctite on all my threads just to be sure. You're always going to get some vibrations, even the changing stresses of your motor pulling in various directions as you fly is going to work things loose. If things come loose and your motors begin to shift about then your quad is going to start spinning and doing all kinds of crazy stuff.

Oh, and what Cheezny said about PiDs too :)

Cheezey
Posts: 25
Joined: Tue Apr 08, 2014 11:38 pm

Re: Wibbly wobbly...

Post by Cheezey »

Andy7 wrote:Re your motor mounting screws.
Reducing your vibrations is the key to keeping all your screws. But I also put a drop of loctite on all my threads just to be sure. You're always going to get some vibrations, even the changing stresses of your motor pulling in various directions as you fly is going to work things loose. If things come loose and your motors begin to shift about then your quad is going to start spinning and doing all kinds of crazy stuff.

Oh, and what Cheezny said about PiDs too :)


OK, I modified my mounting setup - instead of bolting directly to the frame, it's reinforced with metal brackets, nuts + longer screws, and loctite. Haven't had a chance to test-fly it yet (left transmitter on all night and out of AAs) but I will when I get the chance. Thanks.

waltr wrote:Since the motor screws come out re-check that they are all properly tightened.
This may be caused by excessive vibration in the motors/props (and further indicated by a slight improvement in stability with the gryo LPF).
All the motors/props need to be balanced so there is very little vibration as seen in MultiWii Config sensor graph.
In addition the PIDs probably require some tuning but not until any vibration issue are resolved.
Once you are ready to tune the PIDs see this video:
http://www.youtube.com/watch?v=YNzqTGEl2xQ


OK I'll bookmark that to look at after a couple test flights.

Cheezey
Posts: 25
Joined: Tue Apr 08, 2014 11:38 pm

Re: Wibbly wobbly...

Post by Cheezey »

When the power is on, one of the motors seems easier to spin. Could one of the ESCs be at fault? Because it tends to flip over in one direction.

Noctaro
Posts: 280
Joined: Thu Sep 08, 2011 11:15 am
Contact:

Re: Wibbly wobbly...

Post by Noctaro »

Hi,
first you probably need to raise your minthrottle in config.h -> http://www.multiwii.com/wiki/index.php?title=Config.h
Did you calibrate your esc? If not, take a look at the calibrate ESC function in multiwii sourcecode. !read the comments!
Be sure your props are not mounted if you activate it.
Alternative method -> http://www.multiwii.com/wiki/index.php? ... alibration

Turn off any selfleveling.
You need acromode to be rock solid before start working with autolevel modes.
All level features are based on acro (gyro only mode). -> http://www.multiwii.com/wiki/index.php? ... lightmodes

-> http://www.multiwii.com/wiki/index.php? ... tion_guide

Hope this helped.
Greetz Noc

Post Reply