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Jan 25, 2011, 04:03 PM
Registered User
Quote:
Originally Posted by Point65
It's hard to see if you have pins 1 & 3 connected on the WMP for the connection between WMP and NK. I would order a new NK, only original are safe to cut in half. Also, not all clones work.
/Bo
I also cut my NK clone in half and found it wasn' t working afterwards

After some investigation on the cut-off half I found that some signals (mainly GND and VCC) are routed around the joystick board to the other side of the sensor board. A couple of jumper wires fixed it

A multimeter and a pair of good eyes should do..
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Jan 25, 2011, 04:04 PM
Registered User
rimshotcopter's Avatar
Quote:
Originally Posted by ppuxley
Thanks RR. Good idea or I could just make up my own using the plug out to the NK from the WMP I have already dismantled,couldnt I ?
Absolutely!! I only suggested this just in case.
Jan 25, 2011, 04:19 PM
Registered User
Alexinparis's Avatar
Quote:
Originally Posted by firetrappe
Has anyone had a go at making one of these yet? : http://www.rc-heli-fan.org/viewtopic.php?f=255&t=80336

(the link is to a German forum but google translates it pretty well).

Si.
This is absolutely fantastic !
Jan 25, 2011, 04:22 PM
Registered User
Alexinparis's Avatar
Quote:
Originally Posted by Schorschi
At the moment i only connected a Receiver on the Board. Device Detection is connected to VCC. NC isn't detected and the FW works without problems on the GUI. Is it possible that the Device-Detection don't work??

Georg.
does it impact the cycle time ?
Jan 25, 2011, 08:35 PM
MultiWiiHead
Centurian's Avatar

Comming to Terms with PID Terms


I've been struggling to truly understand the PID coefficients. My tuning has gotten better and better, but I think I finaly understand the PID terms and thought this might be of help to some...

Let me define CSD as transmitter Control Stick Displacement. In the case of MultiWii, 1500 is center, so the control channel receiver output -1500 is CSD. This value will be positive or negative number depending on direction of stick displacement

And define GYRO as the gyro output. The gyro(s) are calibrated to zero at start up. Sense of angular velocity is a positive or negative number depending on direction of rotation. GYRO is a measurement of angular velocity like degrees/second or RPM.

There are 4 items that make up the output of the PID forumula.

1) CSD

2) P is GYRO * the P coefficient. "P" will always try to stop any and all angular velocity. This result drives GYRO back to zero.

3) I is the cumulative sum of the CSD - GYRO. This is trying to match the GYRO to CSD meaning the CSD is really trying to act like a request for angular velocity(gyro output). If the angular velocity matches the perceived CSD request for angular velocity the result would be zero. Don't forget it's cumulative, each time it's calculated, it's added to the previous result. So the "I" term can and will "wind up" but is limited to a maxium sum which is about +/-20 degrees of rotation. This "I" term is what I think of as heading hold.

4) The D is change(delta) of GYRO from the previous reading (last 4 readings actualy). "D" is trying to do is prevent angular acceleration. This was the part that I did not previously understand. If the angular velocity stays constant (no angular acceleration) the result of the "D" term is zero.

Today I used this newfound understanding to go back and retune my tri & quad and I am very pleased with the results. The Tri is large, about 38" dia, the quad is small and squirrly @ 17" diameter. The feedback frequency (wobble) is very fast on the quad and much slower on the tri due to their size difference. They are both pretty light.

In both cases I decreased the pitch & roll "D" to absolute maximum(Note this is a negative value). I can see no downside to this and in both cases I was able to increase "P" as well because the large "D" coefficient trys to resist angular acceleration which dampens the feedback (wobble) normaly caused by a large "P". Both machines are now flying better and the low throttle descent wobble has been greatly reduced/nearly eliminated.

Both machines fly like submarines now. They are so well dampened that it's like flying in water rather than air

One more thing to be aware of is the tail servo output response on a tri does not include the "I" term at low throttle. This is to prevent "wind up" on lift off preventing a large yaw jump. Because of this, I as I compaired the servo response with my PID changes, I was confused until I finaly figured this out!!! To observe the real yaw servo output, move the throttle stick to hover position (motors on or off).

Hope some of this makes sense, it took a LONG time to get thru my thick head!

NOTE: Poorly balanced props will result in bad data comming from the sensors which will be amplified by your PID coefficients. Comes down to garbage in, garbage out... your sensors are your friends and your props are their enemies!!!!
Last edited by Centurian; Jan 26, 2011 at 02:00 AM.
Jan 25, 2011, 08:54 PM
master of the universe
captaingeek's Avatar
Quote:
Originally Posted by warthox
freaking awesome! loved the rocket ship take off at the end!
Jan 25, 2011, 08:58 PM
master of the universe
captaingeek's Avatar
Quote:
Originally Posted by Centurian
I've been struggling to truly understand the PID coefficients...
OK can you help me understand this by explaining it in a few sentances so that a 1st grader would understand it

any notes on pid tuning steps? here's how i've been trying:

using defaults adjust everything except PID's appropriately then:

1) set P til oscillations. Reduce by 1 point or appropriately
2) slightly tweak I settings. a little goes a long way.
3) finalize by tuning D.
3a)fresh battery
4) Go back and adjust P one last time.

weight / payload will changes will have little effect once tuned.
Jan 25, 2011, 09:27 PM
Registered User
Quote:
Originally Posted by M4d_D
hi guys ,
you might remember my h6 hexa ...


it flew quite good but look what happened to it....

segmentation





flying weight of the tri is 370g , the quads weight is 430g
they are great funcopters ....

what do you think ?

chers

Cool !
What is your quad spec? (Motor & ESC)
Jan 25, 2011, 11:04 PM
MultiWiiHead
Centurian's Avatar
"P" fights all motion... increase until you get a feedback wobble, reduce by ~20%

"I" is heading hold.... increase until you get a bounce back when you release a big stick input.

"D" the bigger(note this is a negative term, bigger in a negative sense) the better from what I can tell this tries to smooth out any rotation. The farther from zero you run "D" it appears you can further increase "P"

I'm interested in any feedback (no pun intended).... I guess my current bottom line is a big (negative) "D" is a good thing. I'm flying 2 very different machines with "D" maxxed out with good results, YMMV


Quote:
Originally Posted by captaingeek
OK can you help me understand this by explaining it in a few sentances so that a 1st grader would understand it

any notes on pid tuning steps? here's how i've been trying:

using defaults adjust everything except PID's appropriately then:

1) set P til oscillations. Reduce by 1 point or appropriately
2) slightly tweak I settings. a little goes a long way.
3) finalize by tuning D.
3a)fresh battery
4) Go back and adjust P one last time.

weight / payload will changes will have little effect once tuned.
Last edited by Centurian; Jan 26, 2011 at 02:02 AM.
Jan 25, 2011, 11:37 PM
Registered User
Borneoben's Avatar
Quote:
Originally Posted by gtrick90
Tested with Spektrum DX7 SE w/AR6100

Next I'll try with JR 721 DSM2 and AR7000

Ciao

Luca
No No No!!!!

You must continue to get teh buttuns working on teh Cats Whiskers LCD first!!!
Jan 25, 2011, 11:39 PM
Registered User
Frank.T's Avatar
Quote:
Originally Posted by ghost2212
Anyone?
Did you had a look here?

https://spreadsheets.google.com/ccc?...CKDQ6O0L#gid=0

//Frank
Jan 26, 2011, 12:16 AM
"Let's put a camera on that.."
spagoziak's Avatar
Quote:
Originally Posted by warthox
Marcus, this is increcdible!!
Jan 26, 2011, 12:45 AM
Registered User
motorhead's Avatar
Quote:
Originally Posted by Centurian
I've been struggling to truly understand the PID coefficients. My tuning has gotten better and better, but I think I finaly understand the PID terms and thought this might be of help to some...
Thank you for this. I cranked my P up to 4.5 and it was fine for test hover inside but outside in wind and decending it got the shakes. I had to drop the P to 3.2 to get it to stop. My D is -15 so I will increase it and try to get my P back up. I think that I might soon see the light at the end of the tunnel on the NK working properly.
Thanks.
Mike
Jan 26, 2011, 12:55 AM
Registered User
Quote:
Originally Posted by Centurian
"P" fights all motion... increase until you get a feedback wobble, reduce by ~20%

"I" is heading hold.... increase until you get a bounce back when you release a big stick input.

"D" the bigger the better from what I can tell this tries to smooth out any rotation. The higher you run "D" it appears you can further increase "P"

I'm interested in any feedback (no pun intended).... I guess my current bottom line is a big "D" is a good thing. I'm flying 2 very different machines with "D" maxxed out with good results, YMMV
Hi Centurian
Because "D" is negative value so I would like to more clearify about the higher "D" / Big "D"/ or maxx "D" , it's mean close to zero or far from zero ?
Jan 26, 2011, 01:19 AM
Registered User
Quote:
Because "D" is negative value so I would like to more clearify about the higher "D" / Big "D"/ or maxx "D" , it's mean close to zero or far from zero ?
" D " ranges from -40 to 0, so smallest is : -40,.... Biggest, highest or max out is: " 0 "

Cheers