Building the "K-Quad"

[CurryKitten]

Hey Bowerz,

Yep, that was my NetFPV project. There's a thread about it here somewhere, but I'm sat in the car at the mo and can't find it. We still aim to fly something over the net just for fun, but me and Atarix - my remote end of things have both been busy with other bits.

Meet up for a fly would be cool, I'm just down the road in Whiteley :)

[krikey]

A gaggle of K-Quads. Now wouldn't that be cool. Get some footage if you can.

[krikey]

Looks good, add on your VTx and camera and you're good to go.

[DWiskow]

I have mine built now . . . KK2.1 FC, Turnigy 1811 3800kv Motors, Turnigy Plush 10A ESC, GemFan 5030 Props with 2S 1300 & 1600 Lipo's . . . can anybody share their KK (2.1) setup as a starting point for me ?

[CurryKitten]

Sure, although I'm running the Steveis FW which will make the PI values look a bit weird.  What are you running on your KK2.1 ?

[DWiskow]

Just updating to Steveis v1.11S2 (or should I be using v1.12S1 - Beginner ?)

[CurryKitten]

I believe the idea of 1.11S2 is to allow it to handle acro stuff nicely.  The beginner is there to try and act a lot like the 1.6fw on the original kk2.0 board.  So if you want to fly using self-level that might be better.

What I have right now are -

mpu6050 settings
gyro: 2000
acc:   4
filter: 256

Setting the gyro at 2000 means the PI's are 4 times the normal values, so I have

roll    180/300/100/80
pitch  220/400/120/80
yaw   260/80/200/40

It's certainly not done yet.  I was working mainly on trying to get the roll right, so the pitch gains are still too high.  I can get smooth flight if I go slow, but tend to get some oscillations at higher speed. 

My last test flight looked like this, I just need more time to keep tuning/messing until I'm happy -

K tuning session, with lipo beeps making me want to kill myself

I believe the voltage sensor in my 2.1 is off as well, so was getting a load of beeps. 

[DWiskow]

Thanks . . . loaded v1.12S1 ("beginner") and then set my PI's to a quarter of the values you provided . . . hovered (inside) in self level mode at medium rates on my Taranis (I have theses setup at 100%, 50%, 40% for "High", "Medium", "Low").

Briefly tried ACRO, but I think that is a little bit above my skill level at the moment.

Still feels a little bit twitchy, but need to fly it outside with a bit more space . . .

. . . so, off to PID tuning school for me

[CurryKitten]

You need to do you PI tuning in manual mode - just hovering until you are happy that it's staying steady.  Only move onto tuning auto-level once you've done this.

I do generally find auto-level is a bit twitchier in these little quads, but the kk2.1 seemed not too bad at all.

This is all a lot easier once you are outside - even these little quads inside a house feel like an instant death machine ready to destroy your walls and things.

[DWiskow]

After struggling with this issue for a while [i.e. P, I and what good looks like], this video on YouTube suddenly made it all clear to me . . .

http://youtu.be/YNzqTGEl2xQ

. . . and the principle of addressing one axis at a time and first getting P for that axis optimised before moving on to get the best setting for I makes perfect sense.

I think I will "string" my K-Quad up on a static rig to tune it one axis at a time using some of the information gathered together here http://www.rcproreviews.com/kk2-0-flight-controller-setup-and-settings/.

There is also a very simple explanation of Self Levelling settings by RCmanchild here http://youtu.be/f0Bh3fMGHbM.

[DWiskow]

CurryKitten, are you running stock firmware on your Turnigy Plush ESCs? . . . or have you re-flashed with BLheli firmware ? . . . flashing with different firmware should make the quad more responsive and allow higher gains without introducing oscillations (but you will have to re-tune the KK , of course).

[CurryKitten]

I'm running the stock firmware, I looked at the BLheli update, but the updating procedure looks like such an effort that I never got any further than this.  I know it will fly smoothly on plushes, I've got my other mini H quad going smoothly, and had a previous iteration of the HK glass fibre mini frame running smoothly.

That said, if I notice some Simon K flashed 8-10a ESCs, I might well give them a try

[DWiskow]

The Blheli update process looks complicated at first glance, but it is actually really simple and takes only 3-4 seconds per ESC. It is just as straight forward as flashing a KK2 with updated firmware . . . all the work is done automatically in the BLheliSetup software (the equivalent of the KKmulticopter Flash Tool).

The trick is connecting to the ESC (without having to solder to the tiny pads) . . . I 3D Printed a jig/clip into which I inserted 4 spring loaded test pins (easy if you have the pins and once you have designed the jig) that sets them at exactly the right position/angle to hit the four pads (spaced at 1mm) on the ESC . . . then it is simply a matter of holding the spring loaded clip (connected to one of these $10 USB programmers http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=25433 with three wires) against the pads on the ESC and clicking two buttons on the BLheliSetup software running on your PC.

If you zoom into the picture below you will see the test pins protruding from the bottom of the clip. You then just connect the "black", "red" & "white" wires to the other end of the appropriate pins (there are pictures of all the BLheli compatible ESC's showing the connection points coloured  "black", "red" & "white" in their documentation https://github.com/bitdump/BLHeli/blob/master/SiLabs/BLHeli%20supported%20SiLabs%20ESCs.pdf). The wires have female servo connector pins crimped to them and some heat shrink to cover them at one end (the other end is connected to the cable that comes with the Hobbyking Toolstick using a normal servo connector). Over 90% of the SILABS ESC's use this "four pads in row spaced at 1mm" style of connection, so this is good for pretty much all BLheli ESC flashing.

All the advice I read says that running BLheli (on SILABS ESC's like the Plush Series) or SimonK (on ATMEL ESC's) absolutely transforms a multi-copter.

[CurryKitten]

Oooh, interesting.  Yep - all the guides I'd seen involved soldering to tiny pads.  Obviously the non-soldering solution is a lot more desirable.  Hmmm, I saw you could use the arduino for flashing as well, I wonder if I could build something for my leonardo that would do this.  Not heard of spring-loaded test pins before.  I take it the idea is that you can push them down onto the pins on the esc and they stay there, and there's less risk of them slipping or whatever ?

[DWiskow]

Yes, an Arduino will work as the "programmer" too and is driven directly from the same BLheliSetup software (it downloads and runs a programme on the Arduino automatically . . . without destroying the Arduino Bootloader, so you can simply revert to your previous Arduino programme when finished . . . you can actually use the KK2 for this).

On the Arduino you use three of the pins on the [six pin] ISP Header. Have a look at this video on YouTube to see the process

http://youtu.be/P2agnNY5D-8.

You just connect the "black", "red" & "white" to three header pins on your Arduino once it is running the BLheli Programme and then click on the two buttons ("connect" and "flash") on the BLheliSetup Programme running on your PC (whilst holding the spring loaded clip in place against your ESC pins for a few seconds).