MultiWii / NAZE / SP Racing F3 Problem with MultiWii SE -- yo-yo effect during flight

[Garret H]

Hello,

I'm wondering if someone can help diagnose a problem with a Multiwii SE board I bought from Value Hobby. This is my first time using one of these boards, so I'm wondering if I don't have the settings quite right. Essentially, I am getting a yo-yo effect during flight. The throttle is very sensitive despite a curve and expo dialed in. After take-off, the quad shoots up in the air....then it descends rapidly, then shoots back up. With good throttle management, you can control it slightly, but the flight is not level by any means. I haven't messed with too many of the default settings other than the initial config which I know I did correctly with the help of a friend who uses this board. He has the exact same setup (different radio system) and his is flying fine....he initially reported the same problem, but changed RXs and the issue went away. I did the same but the problem persists.

Any help would be appreciated.

Thanks,
Garret

 

[RTRyder]

The RX can certainly do that, I have an EZUHF that is doing the same thing on every multi I put it on so I can only assume it's a problem with the RX as it happens on both a DJI Naza and a Quadrino Multiwii. Having the P value for altitude too high can also cause it as well as not having the baro covered with open cell foam. The only other thing I can think of is you have altitude hold turned on all the time which would be especially noticeable on landing where it would pogo up and down until the baro settled down and adjusted to ground level altitude. I never fly the Multiwii boards with altitude hold on, I only use it if I want to hold position for a short time. Even though A/H is much better in the 2.1 code it still isn't up to the same ability as MK or DJI.

I would start with hitting the reset button in the Multiwii configuration GUI and then write the settings to put the board back to default settings making sure that altitude hold isn't set on any of the Aux channels and see how it flys then. It SHOULD at the very least be relatively stable in a low wind hover and FF with just autoleveling turned on or in manual flight mode with the default settings, if it isn't then try swapping out the RX again making no other changes and go from there. Also try setting up a new model in the TX when you do swap the RX just to make sure you're at a known good starting point.

Ken

 

[Garret H]

Thanks for the help; I tried everything you suggested and really thought that would do the trick. But, I just went and flew it and nothing was different. I called Value Hobby and they were no help....all the guy told me was that he didn't use that board personally, and that the MultiWii boards are hard to program so he wouldn't know. ?? I'm starting to think I got a bad board.

Garret

 

[RTRyder]

Thanks for the help; I tried everything you suggested and really thought that would do the trick. But, I just went and flew it and nothing was different. I called Value Hobby and they were no help....all the guy told me was that he didn't use that board personally, and that the MultiWii boards are hard to program so he wouldn't know. ?? I'm starting to think I got a bad board.

Garret

Nice support from the vendor...

Actually he's wrong, they're easy to program, difficult to tune (at times). The only other possibility is the Multiwii software is configured incorrectly in the config.h file, either the wrong board type or an sensor is defined that isn't what is on the board. If you're 100% certain all of that is correct then it is most likely a bad board. I've got three or four variations of Multiwii boards here and all of them work fairly well with default PID settings when the sensor configuration is right in the software. Problem is unless you know exactly what sensors/gyros/accelerometer/etc are on the board or the board type is predefined you can tear your hair out trying to figure out what the proper software settings are and usually these things come with zero documentation so no help there. I've also known of the same board having different barometers and gyros depending on when it was made so unless you know that particular baord and its revisions fairly well its easy to get it wrong.

After the first couple undocumented Multiwii I worked with I began to think Mikrokopters were actually pretty easy to setup and tune!

Ken