DYS Smart 3 - extreme frustration

[magicdougie]

Been tinkering with this for ages, and damned if I can get any smooth footage out of it. Thought that I';d ask here in case there';s anything obvious that I';m missing before I give it up and try something else completely different (suggestions for an alternative that actually works are welcome!).

A wee video with the shaking that';s driving me to the edge of madness! https://youtu.be/VYN3poENH5Y

As you can see, the horizon goes all to hell too, but that';s not always a problem. Yeah, I guess I';ve got to the point where even if it just worked intermittently I';d persevere!

The Setup...

Quad:
f450 clone
Naza Lite with GPS
running on 3S and 10x4.5 carbon props, all balanced
40A RC Timer ESCs, and RC timer motors, also all balanced
Flies silky smooth - it';s cracking

The mount:
The gimbal is bolted to two carbon plates attached to a pair of 10mm tubes from this set of landing gear: http://www.ebay.co.uk/itm/Highten-Landing-Gear-Kit-w-Anti-vibration-Cushion-for-DJI-F450-F550-Quadcopter-/221655480752?pt=LH_DefaultDomain_3&hash=item339bb239b0

I didn';t use the legs, as they introduce horrific resonance problems. Instead I use a simple set of these, which have no obvious effect once in the air: http://www.ebay.co.uk/itm/Highten-Landing-Gear-Kit-w-Anti-vibration-Cushion-for-DJI-F450-F550-Quadcopter-/221655480752?pt=LH_DefaultDomain_3&hash=item339bb239b0

The gimbal is on the standard, fairly soft dampening balls that it came with.

The gimbal:
Powered from the balance port of the main battery
Firmware version 2.3b5 (as most people recommend for aerial use)
Yaw in follow mode
Pitch can be adjusted from the RX (standard Turnigy 9X)

I';ve played with the PID settings following all the tutorials and manuals etc that you find online. Nothing much seems to make a lot of difference. The video above was shot using the standard profile from flyingtech.co.uk (who I bought the gimbal from). I';ve had less vibration from some of my own tweaks, but nothing even approaching smooth.

I also read in the Alexmos manual that shaking in flight (and yes, it';s rock solid when you power it up on the bench or hold it in your hand) can be down to interference. There';s not enough play to wrap the cables from the board to the motors round a ferrite ring, but I got a ferrite clamp around them, and another around the power cables for good measure. No difference.

Any thoughts folks? Hope someone has an answer. I';m off to the outer hebrides in a couple of days, was hoping to get some decent footage up there so have tried umpteen things over the last few days. Guessing it';ll probably be too late in the day for this trip, but there';s always the next one...

Go on, make my day!

[Soler]

There are a few things going on in that vid but I think first you need to correct the main issue which is the shaking of the Pan axis.    From the video it seams to be worse in either forward flight or Vertical flight but ok when stationary (not much stationary footage)

From your description your running this setup on a 3S,   What I suspect could be happening is that during the fast moves the overall power available is reduced as the motors are taking most of whats available reducing the pan motors holding torque.

I would try the following

Try for a test flight to power the gimbal from a separate bat to see if the problem is still there
Check that the gimbal centre of gravity is under the centre of the pan motor,  (power of the copter and gimbal and lean one side to the other)
Final look at lowering the PID Values on the Pan motor if the above two are not helping

[magicdougie]

Thanks for the suggestion! I';ll go and try it just now! Actually, make that "just as soon as I';ve charged a battery."

You';re right though, it';s reasonably stable when stationary. And yes, the gimbal seems pretty well balanced (as far as I can tell) under the centre of the Yaw motor.

I';ll let you know how it goes shortly!

[Soler]

When you test with a separate battery also try flighting in all directions,  forwards / backwards and side to side to see if there is any difference when flying in directress directions

[magicdougie]

You, Sir, are a genius. It';s not smooth yet, but it';s not nearly so grim!

I attached an old 2.65 nanotech battery just for the gimbal, simply strapping it on the top of the frame (the regular battery is mounted beneath it). First take off saw some really bad vibration through the whole frame - it must have set up some sort of pretty hefty resonance in there somewhere. Shifting it back an inch and a half seems to have cured it, but I wouldn';t guarantee it';s a perfect fix. Might have to think about attaching the two batteries to the bottom. Can velcro them together and they should be secure enough (they';ll be strapped in place too).

Here';s the video - I did as you suggested and tried a few different directions.

My own observations: It still droops after a banking turn for some reason, but does right itself. It also struggles to climb after it';s been flying for a while. The slow rise at the end of the clip is at full throttle... (nanotech 3.3, fully charged at the start, now showing a voltage of 11.6 - would have thought there was a bit of juice left in that yet!). Guess that';s a different issue to the gimbal though!

Would love to hear any other suggestions you have, if you';ve time to share them, but I';ll put some more work into the PID values tomorrow now that the main issue has been sorted.

Thanks again Soler!

[magicdougie]

Whoops! Forgot the link to the new video! It';s still uploading, should be ready at 20:40...

http://youtu.be/CttfZQ4Ip9Q

[Soler]

Great,  its looking better. At least I don';t feel dizzy watching it

Try lowering the P value on the Pan,  that should help it

I am not sure which motors your running but you might want to try a 4S bat,  if at the end of the flight that was full throttle your running a bit too close to the edge. 

As your flying with a Naza unless your in manual mode it hides the real throttle values in ATI and GPS modes.  If your comfortable try flicking to manual mode to find out where the hover point is on your throttle.  Be carefully though because if the real hover point is say at 80% it will drop like a rock until you bump up the throttle or flick back in to ATTi mode.

The real hover point should be around 50%,  this allows for extra power in turns or when slowing the decent as the G Force will be greater than 1.

[magicdougie]

Thanks Soler. Will give it a try tomorrow (both the Manual test and the P values). I';ll be sure to post a video once I get everything running smoothly!

[Soler]

Just be careful switching to manual

[magicdougie]

Yeah, it really does drop like a stone in Manual, cheers for the warning! Got some 4S batteries on the way.

As for the gimbal. Another tweak today. Progress, but not much. The vibrations have been reduced again (incrementally, but they are still definitely there). Pretty bad straight after take-off but seem to settle slightly thereafter. Not sure why. It';s also not holding a horizon in either direction, particularly when doing banking turns: always ends up looking at the floor. Corrects itself eventually, but it';s pretty mince. Am I right in thinking I need to up the P rating for them? Or would that be the power rating instead?

This evening';s video (or the first half of it, should have everything necessary in there and upload speeds are a sod here): http://youtu.be/GwDtJ5tJQ0k

[Soler]

I would wait till your 4S is arrived,  the PID settings will change when you use a higher voltage battery.


Once you have it then I would run through the full running routine setting P,I & D.


Have fun

[magicdougie]

Right enough, guess I can go back to one battery then. Had it in my head to keep using a separate battery for the gimbal...

Will let you know how I get on, thanks again Soler!