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Old Mar 23, 2011, 11:56 AM
Design > Build > Fly
Qrome's Avatar
Arizona, USA
Joined Feb 2005
3,862 Posts
Awesome video and information. I was coming to the same conclusion as last night I was testing and was not able to reduce the wobble, in fact some of the testing made it worse.
Can you share a photo of the board mounted with the dish cloth?

I am going to do the following:

1. Replace the stiff wires off the board that attach to the wm+ with soft ones.
2. Balance the props better.
3. Mount the board with softer foam / or something.

Thanks for the feedback. It confirms my suspicions.

I am using the FC2822 bell motors. How do you go about balancing them?
Thanks.
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Old Mar 23, 2011, 04:48 PM
SILURIA / UK
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United Kingdom
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Sounds like a good plan!

Sorry, no photos - my Tri flew away! I posted about it the other day.

For the motors I use the zip tied method to find the bit that is out of balance, then build it up with electricians tape until I get the feeling of least vibration.

I don't think those bell motors with crap bearings are ideal. Ones like Warthox uses are best. However they are cheap and the gws props fit straight onto the ones I use.

I will upgrade mine one day.

Let me know how you get on!
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Old Mar 24, 2011, 11:27 PM
Design > Build > Fly
Qrome's Avatar
Arizona, USA
Joined Feb 2005
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Oh yes, I read your post the other day. Very sorry about your Tri and all your FPV gear. Very sad.

What I have done so far.

1. Cut the shafts down so the adapters rest on top of the bell.
2. Balanced props on magnetic balancer (one was perfect)
3. Replaced the wires from the wm+ to the Paris Board with soft wire.
4. Replaced the foam tape with super soft tape (much better)

I flew it after these changes with the default PID settings from 1.7prebis and it is way better. There does not seem to be any vibration from the motors other than the normal running. I still would get the gyro wobble a bit as I start flying it around. I decided to bump the D value up from 15 to 25 as you said. The gyro response did seem to soften but more like it slowed down. However as I would start to move around and turn with yaw it would start to get the gyro shake quite bad. If I was low it would take it to the ground.

It seemed to do better with the D value at 15. I don't like the gyro shake though. I am not used to it. I have been flying a KK board on an X Quad since November and I am super comfortable with it -- loops and fast flying light acrobatics. The Tricopter with the mwc board seems to be ultra sensitive to the gyro control though. Do you think bumping down the P values would be a good next step?
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Old Mar 25, 2011, 07:06 AM
SILURIA / UK
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Ok, worth trying the high D. Every one seems different as to what works / doesnt.

I think there is such a variation in the sensors that you have to try all options

Definately try a lower P - I think it is natural to tend to make it too high. You may also have to reduce D a little with it.


Once you have gone as far as you can try the dishcloth I didn't think it would make any difference either!
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Old Mar 26, 2011, 09:52 AM
Design > Build > Fly
Qrome's Avatar
Arizona, USA
Joined Feb 2005
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Thanks for the great info and direction. My last testing just made me think that the clone wm+ I have been using is not working well. I have read that the clone some times can be ultra sensative when running at 4.5 or 5v. I decided last night to chane out the wm+ and put a genuine nintendo board in. My initial hover tests last night showed it to be rock solid. The graph signals in the gui looked way cleaner too. I will do some more flight testing. Thanks again.
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Old Mar 31, 2011, 03:19 AM
Hamburger
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Joined Jan 2010
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Update to howto

Hi,
this step by step tutorial is really helpful but needs an update. The D values are no longer displayed as negatives, so this simplifies things, but step Advanced Tuning - understanding impact of P, I and D / section D is outdated.

Also, any idea how to describe the meaning of the two level parameters?

Thanks, Hamburger
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Old Mar 31, 2011, 10:53 PM
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NSW, Australia
Joined Nov 2009
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I'm reading all about PID tuning bcs I've just got my Triwii operational to the point of thinking of losing contact wit hthe ground. Admittedly, I'm still to properly isloate vibrations but that's a different point.

Is it possible to produce maybe 3 videos which demonstrate (with the same craft) what a Low P, "correct" P and High P behaviour would look like and similarly for I and D? I'm thinking of Low and High represneting the "needs fixing" ends of the range rather than "almost right", but you could include that too (5 x 10second grabs).

I'm thinking that 5-10 seconds of either flight or hand-held video would make it significantly easier for a new builder to identify the parameters causing initial grief and after that experience and "feel" can kick in.

If I get my Tri operational before anyone gets a chance to do this, I might even try to do some for the general good .
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Old Jul 05, 2011, 03:27 PM
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a great write up
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Old May 09, 2012, 04:36 PM
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United Kingdom, England, Exeter
Joined Dec 2011
108 Posts
Shikra this is a great writeup, thanks and good work, my quad is now flying really nicely. would it be possible to update the bit about D to come inline with the new GUI, i think i have it worked out now but it was a complete nightmare trying to work this bit out.

I am aware this is an old thread but your writeup is linked from the main multiwii FAQ so all the new people trying to work out PIDs will be reading it.

I think the bit about D should read like this (please someone tell me if im wrong and i will remove it to avoid further confusion)


D - this is the speed at which the MultiRotor is returned to its original position.
A lower D will mean the MultiRotor wil snap back to its initial position very quickly

Decreasing value for D: (zero is lowest setting)
Improves the speed at which deviations are recovered
With fast recovery speed comes a higher probability of overshooting and oscillations
Will also increase the effect of P

Increasing value for D: (100 is highest setting)
Reduces the oscillations when returning any deviations to their initial position
Recovery to initial position becomes slower
Will also decrease the effect of P

Aerobatic flight: Decrease D
Gentle smooth flight: Increase D


Al
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Old May 26, 2012, 09:13 PM
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United States, OK, Erick
Joined Aug 2011
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subscribed, now is this the same as ver 1.9 ?

mine is an x copter and the board is a red board with multiwii2012 printed on the back

also can someone give me a good default setting on the pid;s and everything. just a good starting point will be nice. thank you for a great writeup
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Old Jun 12, 2012, 12:01 AM
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United States, IN, Indianapolis
Joined Dec 2005
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Take a look at these ...
https://docs.google.com/spreadsheet/...6V1F5c1E#gid=0

They helped me get mine flyable.

Bob
Northwest Cutout Service
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Old Jul 01, 2012, 02:35 AM
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Auckland - New Zealand
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Great write up with some very good information


they have the multiwii release candidate 2.1 I got it from here

http://code.google.com/p/multiwii/downloads/list

But it won't read my board ? my board says Spider 2.0
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Old Jul 01, 2012, 12:23 PM
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United States, IN, Indianapolis
Joined Dec 2005
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Using the GUI and the Subtrim and Endpoint adjustments on my DX7
With the outside TX trims all centered I was able to make ALL my channels 1000-2000.

It took awhile to get things just right because of some interactions.

Afterwards, my Quad was MUCH easier to fly and more stable.

I had ALWAYS had problems with my YAW, but that has gone away now too.

I suspect that there must be something unique about the total frame length in the code.
Not sure mind you, just a suspicion.


@adrian
was the new code generic ?
Or, Might it need some "UN"commenting for your particular board ?
Just asking as I am not sure.

L8r

Bob
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Old Jul 01, 2012, 04:48 PM
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Quote:
Originally Posted by birdofplay View Post
Using the GUI and the Subtrim and Endpoint adjustments on my DX7
With the outside TX trims all centered I was able to make ALL my channels 1000-2000.

It took awhile to get things just right because of some interactions.

Afterwards, my Quad was MUCH easier to fly and more stable.

I had ALWAYS had problems with my YAW, but that has gone away now too.

I suspect that there must be something unique about the total frame length in the code.
Not sure mind you, just a suspicion.


@adrian
was the new code generic ?
Or, Might it need some "UN"commenting for your particular board ?
Just asking as I am not sure.

L8r

Bob
Hi Bob I'm a new to all this quad stuff what is the code generic ?
Cheers
Adrian
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Old Jul 01, 2012, 04:59 PM
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United States, IN, Indianapolis
Joined Dec 2005
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you said you got code from that LINK,

So ...

I figured that the CODE might be Generic,
Meaning that is was written for a Number of different types of controllers
but could be made to work with any specific type by EDITING the CODE
and "Uncommenting" the type that you have.

It was only a Guess. so I can t be much more specific.

Now IF you are talking about the GUI which is what I mentioned to TUNE up the
Channel pulse widths. then I cant even guess on why it wont recognize your board.

I am still trying to figure out a lot of this stuff myself.

I think we might BOTH be happier flying big gliders down a Wellington :-)

L8r
Bob
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