Help with multiwii quadcopter

[kaos]

thx peter. that is what store level means - calibrate ACC. I am sure I did that for both ACC and MAG. but I will do it all over again to be sure. and try.
sharp eyes, it is a DJI 450 frame (even i had a hard to to find the marking on it ;; ). now you know how much I know about building quads. I just went into a shop and looked at the frame, hmm, plastic, indestructible, and bought it about 1 yr ago planning on using it as a learning tool for multirotor craft.
how much the prop wash would affect a quad? you can see i am hovering at a very low level only 2-3 ft, would that be the cause of it is not holding perfectly?
(cause I don't want to punch a hole through my garage ceiling, it is better to hit the ground than hit the ceiling, cost more to fix ceiling than quad. )
as of now it is already pretty stable, comparing to a cp heli. (again, had no experience with multi before)
I will try to let go my fingers after I reset the ACC/MAG and try and adjust the D accordingly.
I have seen those vid people sit their quad at eye level and push it down, it will come back up to where it was. Was that using level mode or with altitude hold?

another thing is the rc rate. you said 3.5 max and you have tried 3.0. mine only goes up to 2.5 max, I tried yesterday anything above that return as 0.04. May be this is another of the Android app - Multiwii Configurator's bug. May be I should start using the other android app - Multiwii EZ. what android app you use to change settings in the field? I really like these android app, don't need to connect wires.

Thx again. will report back.

[GTiDon]

I have seen those vid people sit their quad at eye level and push it down, it will come back up to where it was. Was that using level mode or with altitude .

You need sonar for that accuracy. And an optical flow sensor for perfect position hold. Specially indoors.

Sent from my LT18i using Tapatalk 2

[kaos]

ah, no wonder.
I just tried a few packs with reset mag, and reset acc for acro and stable mode. I would say it is pretty stable as far as I can tell. when i hold it in one position, it will start to drift (not on axis but by the whole) to left/right or up and down slowly. I can let go my throttle finger, but need to keep right finger doing small adjust to keep it from drifting into the wall or ceiling. but the drift is very slow, much slower than a cp heli for sure.
I do have a lot of blade wash in the garage with 4 blades running. I almost can feel the drift is with the wash around.

one thing i noticed, when i pitch the quad, it will dip with either mode, I thought the CB would compensate for the less vetical thrust when the quad is tilted to turn. or it is the same as heli, you do need to compensate with throttle while tilting the quad for banked turn?

[jhsa]

yes, you do.. well, at least I do with mine
Mine is not a very clever one.. I do have to fly it

Just an arduino pro mini and a wii motion plus sensor and nothing else

João

[kaos]

mine is a HK mega pro board which use a meg 2560 chip has 3 axis gyro, triaxial sensor, barometer built on it and an ext. GPS attached (I have not turn on the GPS mode yet, can't get a signal in in the garage )
good to know that. need to learn every nitty bitty thing. since I have no knowledge of what to expect.

[jhsa]

just go out and fly it.. you were flying it in it's own prop wash.. that is turbulent air and makes it unstable.. when you take it outside and lift it about 5' in the air it will be stable..

[kaos]

probably over the wkend. After I get the twin lipo set up. I am using 1 3S 2200mah for now, fly time is about 6-7 min. I am going to load 2 of them for real fly in parallel and hope to get close to 12 min.
By the way, can you switch different mode mid air? or have to land then switch? like between acro/stable/alt hold and GPS hold/GpS rth.
my guess is yes?

PS: I have increased the RC rate to 2.5 (that is the max from the android app can put in) with a 45% dual rate in tx seems to be able to handle that ok.

[jhsa]

You won't gain the double of the flight time.. don't forget that you are increasing the weight as well.. In fact I wouldn't be surprised if you increase the flight time by a couple of minutes only..
You could be driving the motors away from the point where they are more efficient, for example. But nothing like trying

You can switch modes while flying.. but make sure they are well tuned..

[kaos]

I know i won't get double time as you stated. but close. since the increased weight is not doubled from single lipo (take the weight of the empty quad into account too)
I just tried with a 2800 mah lipo and it reached 10+ minutes before the LVC cut in. I think 11+ min with 2 2200 mah is reachable. but only actual trial will confirm that. It will take a little fiddling to fit 2 in there though.
both acro and stable mode are 'tuned' as far as I can tell (if that counts anything at all at this stage ). Into a new area is always exciting!
Hope the weather will cooperate this wkend, certainly don't like to fly in 15-20 miles wind as maiden.

[kaos]

1st day without rain or strong wind. well, got a few minutes before dark to 'fly', actually move around a few more yards in the front yard. I guess I am not used to quad. the yaw rate is still very slow comparing to heli or plane. I end up with sliding instead of turning. while the throttle is very sensitive and yaw is very slow, that really mess up my control.
It appears it flies fine, beside the slow yaw. I really don't have a good comparison of ACRO and Stable mode yet. Don't feel much difference in the yard either.
I have throttle expo at 0.5 and in tx 0.3 , the quad still moves up and down quite unexpectedly while turning the head. I think I am used to compensate on throttle when I bank, and the yaw is so slow I end up increasing the throttle before it turns and it goes up, so in response I lower the throttle, and now the head turns and orientation is messed, so end up the quad will go up and down when I try to fly back and forth at turning point and instead of turning , it is more like sliding.

i wonder if this normal for a quad. the 1st time I power it up, forgot to trun on the expo (around 40) in the Tx. when I try to lift it up, it is so sensitive and responsive, it flip really quick up side down. then I turn on the expo, it is just fine. a 40 expo will end up in such huge difference? tiny stick movementu will flip the quad without expo?

[Peter]

I van turn my quads within a meter at speed. But I also use pitch and roll and a lot of throttle. Don't try that yet

What also could be the case is that you have vibration problems. Quads go jumping when they react on vibrations. They also have a tendency to "fall inside the turn". Using expo to smooth input, result in less movement of the quad and so less reaction of the gyro.

Set the Low Pass Frequency of the gyro to 20Hz and see if the jumping and twitching goes away.

But you also need to get used to how a quad turns.

[kaos]

thx , peter. I will try those.
I definitely need to get used to this slow yaw thing. I was trying to turn but the head is not turning and end up with a slide. so a figure eight becomes a sliding left then forward then sliding right and backward and so on the other side of the 8.

I will do a trace of the gyro graph at mid stick to see if there is vibration problem.

[kaos]

well I did run a trace of the gyro to see if there is vibration problem. this is the trace graph. I raise the throtle to close to mid stick till the quad is very light on ground.
To me, those gyro seems to be pretty stable, just a little ripple. at the end the roll gyro has a big dip that is the time the quad start to lift from the left side so I chopped the throttle to set it down. I was inside the house, really don't want to lift it indoors at this time.
Does that gyro graph looks normal to you?

was looing into the low pass frequency. what you know, a few days ago, I have to do a recovery for my PC because Windows update crashed my computer. But I think the multiwii.ino file is considered part of program file by windows, so it was reverted back to original. I lost all my config.h setting. now i need to figure out what setting I put in there.

[kaos]

well, before i change the lowpass filter, I tried 3 more packs just now. played a little again with rate/expo both in MW and Tx. I think I got it tuned to an acceptable degree.
I noticed my stable mode is about the same as acro mode while flying not much difference I can tell, but during take off, the stable mode always end up with the head turning about 60 degree to the right once air borne and correct it, it is fine. Do you have this phenomenon?
The other thing is in either acro/stable mode, the quad tends to go up. any time I have it hovering dead stop and let go the throttle, the quad will start to go up slowly 1-2 ft per sec never go down. always start to go up. the throttle is untouched. Wonder why
on the 3rd pack, I have removed all expo from throttle in tx and MW, kind of afraid to do that because of the bad experience while having a bad motor. you know what, now the left stick control feels much much better. I guess that throttle expo really gave me a hard time.

now my MW setting:
RC rate is 2.5 (max) expo 0.0
pitch/roll rate: 0.8 yaw rate: 1.0
Tx:
Pitch/Roll: 35% dual rate , 40% expo
0 for rudder both d/r and expo
throttle is 0 expo/dual rate

I think I need to fly a dozen pack to get used to it now.
Boy this thing is harder than heli to be tuned right. but inexperience probably pay a major role.

another question I have is: Is there a way to move the hovering throttle stick point some what higher than mid stick? I am used to fly heli and hovering just above mid stick but as of now the quad is hovering right at mid stick, that may throw off my throttle rudder control some what. Can I do this by changing the 'mid throttle' to 0.6 or should I use the throttle curve in Tx to have the 50% throttle a little above midstick?

[kaos]

here is a vid I did today describing the issue. this was my 1st pack today. so finger may not be warmed up yet. 2nd pack is better but the main issue still the same as described in the vid.
https://www.youtube.com/watch?v=ASw2kzqJLt8

edit: 2-4-13
I think this quad is close to be truely airworthy. spent some time while watching the Superbowl to set it up for 2 2200 mah lipo to extend the fly time and some led light to aid in orientation also for night flying.

here is today's try. I like the throttle response with heavier setup, the 'lag' seems to be gone with throttle. but the yaw is still 'too slow' to my liking. Any trick to make that yaw faster?
http://www.youtube.com/watch?v=Lw8Ny-uOOgw

It is almost like the stick gives the final position of the head, but it takes its own time to get there. if I move the stick say 1/3 it will starting to turn til about 40 degree is reached, if I turn half stick it will turn 180 degree but it turns on its own slow paste.

[kaos]

ha, found a way to increase yaw rate. don't know this is the right way or not for multi but it does the job. I recall my heli piro rate is tuned by limit, so why not try on the multi. they are all gyros. Here is the result (except the last 20 sec )
http://www.youtube.com/watch?v=msqsbnHj37U

[asoliman]

thx for replying GTiDon. I finally got my quad be able to hover in the garage.

Hey Kaos ,, I wonder how were you able to get your quad to fly ! I'm really having a very hard time .. I Checked the GUI and I when he quad is leveled and I increase the throttle .., Motor speeds are not equal Even if I tried to calibrate the ACC several times ! any help is greatly appreciated
thanks in advacne Cheers !
PS That's my very first quad !

[jhsa]

try calibrating all ESC's to your radio.. plug them one by one to your receiver's throttle channel and calibrate them..

also before you should make sure the quad flies well in acro mode and only then attempt to use the accelerometer..

last time I flew my tricopter and quad was last year though.. Don't know how much advanced multiwii got since then though..

João

[kaos]

do as Jhsa said 1st. those ESC needs to be calibrated individually.

[asoliman]

Thank you guys for replying I have calibrated the ESCs using the calibration mode in MultiWii .. I made this by uncommenting a line in the config,h file .. it generates a special code that can't fly the Quad ... Do I have to re-calibrate them using the Receiver ?
What about the motor speeds in the GUI ? will the calibration adjust them ? .. Thanks again

[jhsa]

as I said, I don't know I don't follow the multiwii development since a while, but I think you have to calibrate the ESCs with them connected directly to the receiver.. Give it a try....

João

[kaos]

I would recalibrate each ESC indivdiually. also look at how your motor starts and stop with some throttle. they should starts and stop pretty about the same time. If not, one or more of them are 'off'. if you don't have 'matching' motors (even the same brand and type), you will have problem. That's what hapened to me in the beginning, after replace the one 'non matching' motor, every thing is fine. those 4 motors were of the same kind and brand bought at the same time.

[asoliman]

I've recalibrated Every ESC Individually . using my TX but Nothing changed I have the same motor types and ratings ... really I hate that I have no clue !

[jhsa]

I don't know if you already said it but what does it do? try to flip to one side?
Did you try to fly it with the ACC off?

[kaos]

1st, you have to set the quad up without any sensor besides the gyro (acro mode), if you have recalibrate individual ESC, try to calibrate with the sticks (in multiwii there is a way to adjust the 4 motor spd to some degree with sticks). if all fail, I will really look into replace one or more motor. As I said before, you may have one bad motor that was what I had before. and they are all same type, same brand and bought at the same time. once i replace the motor, the problem went away.

also, Jhsa asked what is the problem, is it just tip a little when it is light on the ground or just flips. if it is just tips a little while light on the ground, it may be acceptable (not perfect), once it is true airborne it will be fine. when one motor is slightly off, the quad will tip a little when light on the ground because it drags one or more footing on the ground.

[jhsa]

If it wants tp flip for example you might have to start to move motors and esc's around to find out which one is not doing it's job properly. But as Kaos said, if your trying to fly the quad very close to the ground it will be very unstable as it is flying in quite turbulent air. you will have to go up a meter or so.. there are other ways to see if the quad is working well.
I for example, hold my quad/tri by it's belly and well above my head (for obvious reasons ) and then apply takeoff power, and check how it behaves. For example. when you try to tip it to one side, the quad will try to tip in the other direction, applying some force to get level again.
I know, there's a lot to check and troubleshoot. Welcome to the multirotor world

João

[Peter]

You cannot look at motor output if you are not flying. It will behave different on the bench because the error in the pid loop builds up. First get acro mode right. Then calibrate acc on the bench and try it in the air. The motors can be calibrated all at once with multiwii as you did, just check if they all stop at the same time as mentioned.

Sent from my GT-I9300 using Tapatalk 4 Beta

[kaos]

Hi, Peter, nice to see yu around again. Since I have mine airborne I have not get it to the next step yet due to lack of flying field. But I am joining a fly club close enough to me this wk (no opening before now ;( ), so that will change for me. I don't have GPS/RTH set up yet. just doing it in the front yard with lazy fly/hovering in acro/stable mode. But I do have my sonic sensor in hand now. soon will be working on that. So stick around.

[Peter]

Yeah, it had been a while. Radio was working well and working on fpv quadcopter and a fpv wing. Both using MultiWii.

1 meter, depron with glassfiber


Wood with glasfiber and foldable

[kaos]

haha, i am also working on fpv quad but mine is like this :
need to practice this 'tunnel vision' through goggle 1st.