Bug causing random flips at take off?

This forum is dedicated to software development related to MultiWii.
It is not the right place to submit a setup problem.
Software download
Post Reply
User avatar
shikra
Posts: 783
Joined: Wed Mar 30, 2011 7:58 pm

Bug causing random flips at take off?

Post by shikra »

I'm back! TriWii no 2 maidened yesterday! Going good too. As stable as the flyaway! (I tested failsafe!! and it works)

Anyway, I found a small bug today (I think).

My setup is WMP+NK. With NK on
If I calibrate for acro and then turn motors on and open throttle, it flips every time.
If I say carry out a motor off (even though they are off) before turning on, no flips - works perfect

Am using 1.7preter. Might help troubleshoot unexplained flips.

Apologies if raised before

Alexinparis
Posts: 1630
Joined: Wed Jan 19, 2011 9:07 pm

Re: Bug causing random flips at take off?

Post by Alexinparis »

Hi,

I tried to reproduce it withITG3200+BMA180 without success.
And I've no more a NK+WMP config...

Can someone else confirm this bug ? (with WMP+NK or WMP+BMA020 )

User avatar
shikra
Posts: 783
Joined: Wed Mar 30, 2011 7:58 pm

Re: Bug causing random flips at take off?

Post by shikra »

What no wmp/nk anymore?? Is like Jesus saying he's given up religion!

I can repeat it every time. Maybe someone else will try soon. I have all default settings for PID etc.

Alexinparis
Posts: 1630
Joined: Wed Jan 19, 2011 9:07 pm

Re: Bug causing random flips at take off?

Post by Alexinparis »

shikra wrote:What no wmp/nk anymore?? Is like Jesus saying he's given up religion!

Don't worry, I've still my beloved triwiicopter with WMP only ;)

To be sure of the symptoms:
1) you have WMP+NK
2) autolevel is active, and I assume you have a fine ACC calibration

3) gyro calibration and then arming motor and then hover = flip
3) gyro calibration and then motor off command (even if already off) and then arming motor and then hover = OK

User avatar
shikra
Posts: 783
Joined: Wed Mar 30, 2011 7:58 pm

Re: Bug causing random flips at take off?

Post by shikra »

Yes thats' it.
Only other thing to mention, the motors on looks good - it's only when start to open the throttle.

Now I think about this, I have experienced occasional strange flips opening the throttle when opening with earlier versions - Quite possibly after a calibration. I never had one in the air.

I'll try some combinations - with NK on/off etc..

User avatar
Ebi
Posts: 17
Joined: Thu Feb 03, 2011 7:28 am
Location: Switzerland

Re: Bug causing random flips at take off?

Post by Ebi »

Hi, I've flown today for the 1st time my Mini-Quad V1.7 prebis with WM+ Original and analog accel. 5DOFIMU.

Flying like in a dream, will post some pictures soon :D

But, after a battery change I was holding it in the hand in ACRO mode just to check that everything was perfect before take-off and when applying throttle the quad had the front motor (flying in + mode) spinning a lot faster than the other one like if I was applying a lot off back pitch !!! I disarmed the motor and armed it again same problem. Then unplugged the pack and plug it back again and then everything was working perfectly.

If I would have taken off without a chek It would have flipped right away....

When the problem occured I plugged the battery having the quad upside down on the ground and 2nd time in the right position.

Sorry but I didn't have time to try again to see if I can make it reproduce the same problem again....

EBI

User avatar
shikra
Posts: 783
Joined: Wed Mar 30, 2011 7:58 pm

Re: Bug causing random flips at take off?

Post by shikra »

EBI - yes I get the same when I turn tri upside down to fit battery.
I assummed the gyros remember that as last good postion. Now I only connect battery when right way up.

Alexinparis
Posts: 1630
Joined: Wed Jan 19, 2011 9:07 pm

Re: Bug causing random flips at take off?

Post by Alexinparis »

When you power the multiwiicopter, there is a gyro calibration at the very beginning.
The copter must not move during this step, but its orientation has no influence.

Your flip could be explained by a wrong gyro calibration at the initialization. credible or not ?

User avatar
shikra
Posts: 783
Joined: Wed Mar 30, 2011 7:58 pm

Re: Bug causing random flips at take off?

Post by shikra »

Yes, I assummed that was true for upside down power up! (edit - wa hholding at the time so definately moving)

I just tried replicating the issue again... Here are results.
I have NK/WMP setup
With NK connected, but disabled by tx switch I didn't see a problems
With NK on, tri level on ground, power up, calibrate, turn motors on, open throttle and it flips... every time.
It is a very strong flip. If I hold tri to prevent flip and do it again maybe 1-2 secs later, there is much less force in the flip. If do say 5 secs later it lifts up one arm just a little and then starts to fall back to level. Always lifts the motor on the front right (as you look from behind)

Hope that helps.

User avatar
Rob
Posts: 77
Joined: Sun Apr 03, 2011 4:40 pm

Re: Bug causing random flips at take off?

Post by Rob »

@shikra

Maybe vibration from frame to board?
Connect to GUI hold frame, power up en look to the screen......

Post Reply