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Old Dec 19, 2011, 01:16 AM
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Svizzera, TI, Lugano
Joined Jun 2011
164 Posts
Hi,
i have finished my flydumini with 2000kv HK motors, Plush 12A ESC, 5x3 3blades, promini and FreeIMU 0.3.5 without baro...

I have installed Multiwii 1.8p2 but the Flydumini it's not flyable...

I have tried with lower PID but without changes...

The flydumini it's too sensible in ACRO mode and have more oscillations in STABILIZE mode.

How can I solve this problem?
How balance 3blades propellers?
I think probably a problem of vibration...
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Old Dec 19, 2011, 06:02 AM
It wasn't me
r0sewhite's Avatar
Augsburg, Germany
Joined Mar 2010
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It is most likely that either your PID settings are too high or that you have too much vibration. The best way to start is to work on the cause and not on the symptom.

So we start at the props: Put the 3-bladed prop on a balancer. We assume that each blade has a different weight. The lightest one will face most upwards, the heaviest one most downwards. You have to decide wether to add or reduce weight.

When you want to add weight, you take the lightest blade first which shows most upwards. Add weight until one of the other two blades shows exactly 90 upwards. The two lower blades now are in balance. Then you take the blade which shows upwards and add weight until the prop will stop turning at no special point anymore.

After your props are balanced you should take a look at the construction. Hold the copter tight in your hand and give throttle to check wether the frame is stiff enough or if there is a range where the frame starts to vibrate badly. Check the whole throttle range. If you can't improve by balancing, you must get your frame stiffer. Paul added some cf rods to the frame kit which should be glued on the lower side of the frame. Did you do this?

If the frame is stiff enough, check the pad which dampens the sensors. The lighter the sensor BOB is, the stiffer the pad must be. Sounds strange but is right. Try a stronger pad.

If you have followed all 3 steps above, all what's left to do is PID tuning. Though there are no real rules in PID settings, I found out that the lighter and smaller a copter is, the lower the proportional (P) value for pitch and roll can be. A good value to start with is 1/10 spread -1. That means if your copter has 40cm spread, divide the 40cm through 10 which is 4 and count off 1, which is 3. With the flydumini you can start with a P value of 2.
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Old Dec 19, 2011, 10:32 AM
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Hamburg, Germany
Joined Jan 2011
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Have to add, the 3200 is more sensitive then the original WMP, please try to enable a LPF setting.
Pid of 2 is too low in my eyes, you can achieve easily 3.4 with the rods and mediocre ballanced setup.
My last build used the 3 bladed ones i will get soon, didnt ballanced them, flew well with different motors, never changed the pids, very satisfied.
I also cant fly it in acro mode (my skills simply dont allow that), but with the ACC from the BMA, its really well and easy for a beginner.
I never tried a 3200 on the Flydumini, but i allready heard from some guys they used the LPF.
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Old Dec 19, 2011, 11:35 AM
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Joined Aug 2011
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Hi' ,
I have the default setup on a quad 42cm/ 6 inch motor/motor , dt750 and 10x4,5 props.
It seems very stable to me but this is my first quad , someone told me to increase the pid and try , but can I ask if I have to rise all the three pid ( rool pitch and yaw)??

Another question I trimmed the accelerometer bma020 but I can't see many differences between on or off, is there a way to test it or improve the accelerometer work?

Thank you
Andrea
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Old Dec 19, 2011, 12:16 PM
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Hamburg, Germany
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try to increase the values for roll and pitch it become more stable or starts to oscilate.
Yaw isnt that important to raise, but you can try too, sure.
You dont see a difference??
Are you sure its on a switch on your TX??
You can also increase the value in the GUI for the autostable strenght, but its a day and night difference, you should feel it.
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Old Dec 19, 2011, 01:16 PM
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Deutschland, Schleswig-Holstein, Kiel
Joined Jan 2011
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i use itg3200 + bma020 with stock PIDs, without lpf.

works fine.

but it is necessary to balance props as well as possible!!!!

juhuu

today my nanotech lipos 460mah in 2S +3S arrived.
will report my testings with the flydumini this evenning, they are just loading....
hope they will deliver enough current, other than my "old" usual 2S batteries.

good news for the "black-colour"-lovers. the colour of the nano batteries is very very dark blue, almost black
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Old Dec 19, 2011, 01:33 PM
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Quote:
Originally Posted by Goofy23 View Post
try to increase the values for roll and pitch it become more stable or starts to oscilate.
Yaw isnt that important to raise, but you can try too, sure.
You dont see a difference??
Are you sure its on a switch on your TX??
You can also increase the value in the GUI for the autostable strenght, but its a day and night difference, you should feel it.
Than you goofy for your replay.
Yes I binded the acc on a swtich on rx, on the begining when I switced it on the quad started to drift to right , I trimmered it and know it stay stable.
But the question is what I can expet from the bma020 , an altitude stabilization, in other word if I leave the rc the quad would be fix at the same hight?
Excuse me for the stupid question.
Andrea
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Old Dec 19, 2011, 01:37 PM
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Quote:
Originally Posted by claustro View Post
Than you goofy for your replay.
Yes I binded the acc on a swtich on rx, on the begining when I switced it on the quad started to drift to right , I trimmered it and know it stay stable.
But the question is what I can expet from the bma020 , an altitude stabilization, in other word if I leave the rc the quad would be fix at the same hight?
Excuse me for the stupid question.
Andrea
the bma020 will hold the copter horizontal in roll/pitch axis, but not in height.
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Old Dec 19, 2011, 01:55 PM
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Originally Posted by alteskind View Post
the bma020 will hold the copter horizontal in roll/pitch axis, but not in height.
So in other words it make the Gyro( roll pitch) "stronger and more accurate" right?
So tell me if I am wrong
gps- position hold ( roll pitch altitude?)
barometer altitude old
Sonar - altitude hold

Witch kind of sensor is best to add to flyduino for altitude hold in a gps/ bmao20 / wm+ configuration?
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Old Dec 19, 2011, 02:03 PM
let's brm together!
Czech Republic, Prague
Joined Nov 2011
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nope

gyro is what makes the copter stable - works against external forces that want to rotate it

accelerometer (bma020) is what tells the copter what _position_ in relation to the ground it is
that's why it is needed for autolevel - it is not possible to calculate position of the copter in space with gyro only
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Old Dec 19, 2011, 02:07 PM
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Originally Posted by zviratko View Post
nope

gyro is what makes the copter stable - works against external forces that want to rotate it

accelerometer (bma020) is what tells the copter what _position_ in relation to the ground it is
that's why it is needed for autolevel - it is not possible to calculate position of the copter in space with gyro only
Ok now it is more clear , so with bma020 if I leave the commands the quad have to become leveled by himself, right.
And what about sonar, barometer and gps?

Thank you

Andrea
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Old Dec 19, 2011, 03:04 PM
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Quote:
Originally Posted by claustro View Post
Ok now it is more clear , so with bma020 if I leave the commands the quad have to become leveled by himself, right.
And what about sonar, barometer and gps?
thank you
Andrea
From my early point of view:
The only reliable height hold is possible via sonar at low heights (up to 3 Meter?)
A barometer is very sensible about wind - and a copter is a very windy place ;-) Height hold via gps depends from the accuracy of gps that is imho 3-5 meter.

With some mods, like encapsulating the baro and a sensible IMU, the copter should hold its position with a slight oscillation of +/- 1-2 Meter.

Some copter sw has sonar/ gps/ baro implemented, some not. I would apreciate if someone implement sonar support into multiwii - because its christmas ;-)
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Old Dec 19, 2011, 07:05 PM
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Hamburg, Germany
Joined Jan 2011
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your point of view is rgiht in my eyes.
A better Baro will may help much (Fabio cared for that:-)
Sonar, nice toy, but 3m, hmm not enough, till now i also dont found one who had a good reach.
Oh btw.
Did someone examined the Microsoft Kinect, especially his laser?I have a friend who may can get a few for us for very cheap.
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Old Dec 19, 2011, 07:22 PM
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some flydumini pics, even if they belong more to the flydumini thread:












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Old Dec 19, 2011, 08:36 PM
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Deutschland, Schleswig-Holstein, Kiel
Joined Jan 2011
431 Posts
i tested the 460mah 2S and 3S turnigy nanotech 25/40C lipos with flydumini.

that little packs are amazing!

with 2S even blue LED strip keeps lighting until battery drained - almost no voltage loss.

as my mini is a heavyweight it hovers with 50% throttle, but still is nice flyable indoors.

with 3S my mini hovers at ~25% throttle, and is getting much faster - almost too fast for me (<---noob pilot)

i recommend those little nanotech powerpacks, they deliver high current over the time with little weight. will definetley buy much more of them.

did not measure flighttime - but seemed longer than with usual 500mah lipo
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Last edited by alteskind; Dec 19, 2011 at 08:45 PM.
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