Hi All,

I have flown my quad 12 times now, using the stock pid param as per 3.2.1

I get ~25min per flight with small HD Tube nose-mounted FPV cam.

I now want to attempt Auto-tune to optimize the rig.

 I don't think I am experienced enough to do PID tuning manually.

However, I read somewhere around that Auto-tune can fail on bigger, heavier quads, with low kv motors.

My build is based on the Tarot 650 Sport Quad Frame (X-config)

FC - PixHawk (3.2.1)

Motors - Tarot 4114  320kv    

Props - CF 1550

ESC - HobbyWing Xrotor 40A

Batt - 8AH 6S

AUW : 3kg

1) I would like to know if Auto-tune can be done successfully on this build.

2) Do you recommend that I first upgrade to 3.3.3

Thank you for your valuable comments.

Regards,

Gerhard

Cape Town, South Africa

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Hi All,

Just a Build correction, as pointed out by Tony K

ESC : HobbyWing  Xrotor 40A

Thanks Tony!

Regards,

Gerhard

info@skyfly.co.za

I think you have a very good set up. My only thing was that i did a alot of experimenting with vibration and found a good set up for the pixhawk. Because carbon fiber props at that length transfer more vibration to the frame than smaller props that are plastic. So you have to be more careful with vibration levels. 

Your set up was what i came to conclusion to use after many other ones and ecalc. I am in the air for about 25 min with a 6S 10Ah batter 30C rated. With a gimbal and gopro my quad is over 3.2 kg total weight. 

I wish i had ur radio. I use a turnigy 9x pro with a frsky 8xr reciever. 

My experience with the frame is LOVE IT. However i do not fold it. Because for a number of reasons but i believe its more ridged when you dont move the arms. 

If i was going to upgrade i would get sunnysky or t-motor motors at that range of KV from 320 to 380. I would never experiment with any other ESC. Maybe DYS with BLHeli. 

You should not have any issues. IF you do check vibration. Pixhawk flies great if vibration is low. And if you have calibrated your sensors good. Make sure your solder joints are solid. Very important. But thats all for me, I have had a very successful time with this set up. Only downside is the set up is prone to windy days above 15mph. But has never crashed or anything or gone crazy. 

For alt hold performance i am planning to get a all in one GPS/compass/baro module external. Thats's a future thing. So far i am very happy. 

Hi Tony,

Thank you for sharing.

Since you are flying a similar frame and comps, what are the typical vibration levels according to your log file? I had advise from George that the craft's vibration is way off. Looking at my last flight log it appears well above +-2 on both X&Y

Is it possible that you can load and share a log file of your craft?

Can you share any pointers re ensuring low vibes on your particular craft,

besides what is mentioned on the wiki?

One thing I didn't do was to balance the CF props (1550). For some reason I thought CF are balanced, more than plastic props.  Apparently not so.

So this weekend I intend to do -

prop balancing

Load FW 3.3.3 and re-calb craft

Then hope to fly it and  do further investigation re vibration levels.

Regards,

Gerhard

Hi Gerhard

To perform autotune you must have the following. In alt hold mode and the throttle at or very close to 50%. If the throttle is not 50% autotune wont start. I recommend you perform the 3 axis autotune one at a time. This is set in Mission planner. You will be surprised at the autotune perimeter results. My X8 flys great after autotune. Very Happy

Cheers Henny 

3.2.1?..When you upgrade to 3.3.3 it will be a lot of things to check again....

Hi Emin,

Thank you for your comment.

 I will go through all the set-up/config processes, as from 'scratch' ,  I hope ;)

Regards,

Gerhard

Yes i will as soon as i get a chance to fly its been horrible weather these days in Canada. For pics pls PM me. 

Weather near perfect in Sunny Australia

Gerhard,  those Xrotor 40A are great, you shouldn't have any issues with those and low KV motors.

FWIW my experience with autotune has always been very positive, including  heavier copters (several 5kg+), as long as you have successfully tested your copter prior. As has been said checking vibrations is important, also making sure that your copter responds well to short  and sudden pitch, roll and yaw sharp moves. And before testing that you can test on the ground (copter attached) response of the motors to sharp throttle changes to 100%.

Autotune does not stress a copter more than any airworthiness test should imho, but it may reveal weaknesses if the copter has only been "mildly" tested manually prior. Once you know your copter flies and responds well in stabilize and alt hold I think you will find that autotune works great and is a breeze, even if it may feel a bit  intimidating the first time. As an example here is a 12KG X8 with low 170KV motors (I fly it up to 18kg AUW) that successfully autotuned,  no issue at all.

Cheers and good luck!

Hi All,

I finally completed upgrading / installing FW 3.3.3.

I did the first flight with new FW today.  Wind : Bit warble breezy  Duration : 20min to BattLow FS (set at 22V)

Prior to flight, in MP I did the actions > pre-flight calb

   btw, are there other pre-flight calb which should be done prior to flight?

    (I am not referring to basic pre-flight inspection eg gps lock, mechanical sound)

Tested FM : Stblz, Alt_H, Pos_H 

In Alt_H I made some aggressive R&P stick movements, the Craft seemed to respond 'ok' 

I had a look at the DF bin file -

The 'Vibes' are within the spec as per  http://ardupilot.org/copter/docs/common-measuring-vibration.html

The R&P seems to follow the des R&P, from what I see in the graphs.

GPS R Atl / Alt Baro Alt, AHR2 Alt follows each other, however there is an 'offset' from each other.

See attached files.  I am not sure how to interpret it?

The .bin file is ~13M, too big to load here.

 How else can I share the file?

   Perhaps I should do a short ~5min flight in AltH hover, smaller file?

Thank you once again for your comments, observations and suggestions.

Without it, I will not be able to optimize the Craft in order to further explore and enjoy this hobby.

Next step -

Await a calm no-wind day, then fly it in an open park area, at this time I am flying at home in my backyard.

Regards,

Gerhard

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Hi Olivier,

Thank you for your comments and suggestions. Quite a neat beast you have there!! ;)

As you may have seen from my latest reply, I have done a first test flight today with fw 333

I have in fact done what you have suggested, re AltH aggressive R&P. The Craft seems to follow ok.

I may not have done it as aggressive as you suggest, I will do it next time in wide open terrain.

Once I have evaluated the response from that, I will attempt ATun.

The Vibes graph appears to be within the limits as per wiki, as I understand it.

Unfortunately the .bin file is too large for the group to share since I would have like the experienced community's input such that I can understand if there are any thing 'off' in my setup.

 

Anyway,  have a great day!

Regards,

Gerhard

Cape Town, South Africa

Hi Gerhard

I would personally try the aggressive movements in stabilize as well as alt-hold, so as to minimize the influence of the FC on the throttle.

Try doing an 'auto analysis' in the dataflash logs tab in MissionPlanner, as the results from that should show up any major glaring issues you might have.  

The main 'danger' in autotune is desync.  If you do aggressive movements (go to the extremes of the sticks as quickly as you can) and similarly try and max and min the throttle as quickly as possible, then that's probably as good as you can do.  You have excellent ESCs which others say work well with low KV motors, so you've probably done as much prep work as you can for autotune.  Go for it :)

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