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

T650Q6S8000_1.jpg

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    • 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

  • Hi Gerhard, you 'should' be OK, but you would want to test the motors on the ground first.  I fly a 650 sport as well but I use sunnysky 3508 580kv motors and hobbyking afro 20a eSCs and 1550 props, so you are quite a bit lower KV.  I've never had any desyncs in flight except when using active braking (don't do it!).  it's great that you can fly it successfully manually and I assume you haven't had any problems.

    When I first build/try a quad I always take the props off and 'fly' it on the ground - first of course check the motors are all spinning the correct rotation and then I gun the throttle as fast as possible up and down and make sure they respond as expected.  Some people advise then strapping the quad down (tightly!) and repeating this with the props on but I've never felt comfortable doing that.  I then fly it in stabilize mode and when i'm happy it's reasonably stable in hover and gentle flight I then again gun the throttle up and down as quickly as I can many times as I can take, and also left and right and front and back as violently as possible.  All of these actions replicate as well as possible manually what autotune will do - very quick bursts of throttle on certain motors.  If these tests go well then at least you've done your best before invoking autotune, which has never gone wrong for me yet (touch wood!).

    It's also very much worth looking at your ESC firmware.  Assuming you've got hobby*w*ing ESCs I know nothing about those personally, but they have a superb reputation.  Hobby*k*ing ESCs which I have less so :)  SimonK firmware is known to be prone to desyncs because it focuses more on fast throttle response which is what incurs desyncs on lower KV motors, so I changed to blheli immediately, which has smoothed throttle, and never had a problem although my motors constantly screech which tells me I must be near a desync.

    Upgrade to latest 3.3 and give it a go, I would definitely do it outside over grass as it's a softer landing if something goes wrong!  The only desync I've ever had, when trying active braking, it nosedived hard into a tree and didn't damage anything at all except for a mast.  If I'd been inside a hall I suspect there would have been heavy damage to it.

    Good luck :)

    • Hi Fnoop,

       Thank you for input and advice.

      I have indeed checked and verified the points you mentioned, prior to my initial test-flight attempt.

      And yes, I have flied successfully in stblz m, to date.... ;)

      as well as AltH,PosH, Loi, performed RTL and Land.

      I bought HobbyWing Xrotor, from what I understand their ESCs are pretty 'good'.

      If the ESC 'desync' condition is indicated by ESC 'screeching' sound, at this time, particularly

      from this morning's test result, I did not detect ESC desyncing.

      I made further comments on this main topic thread, points relating to what you mentioned here.

      Regards

      Gerhard

    • ur motors are under powered for a 15 inch prop. Esp if your using 4S. Not that it wont work but thats not an efficient set up..

      • Hi Tony,

        If you are referring to my build, I am using 6S 8AH,

         which I believe is ample for my application.  (See the intro)

        Regards,

        Gerhard

        • no no Gerhard ur good. Very good. You wrote hobbyKING xrotor but i think you meant hobbyWING. those are awesome for low kv. 

          I was replying to fnoop dog lol. 

          • Ahhh Tony,

             Thanks for pointing out my 'typo' spec mistake..... 

                >> indeed HobbyWing...... of course :)

            I also use the Tarot brand 4114 320kv motors.

              The motors really sound great when they spin-up.

            I guess I can't edit the initial topic thread to refect the correct build info?

              I will add the correction in the main topic thread though.

            I am so glad to here there are more DIY'ers using the same frame and components

             which I am using  :)))

            In hindsight, I think I should have opted for higher  kv motors,

             I say this without motivation though.

            btw, which brand/model motors and Batts are you using?

             I am using the GensAce Tattu 6S 8AH

            What is your overview and experience with this frame/components and PixHawk?

            I am using the Taranis X9D+ radio at this time.

            Regards,

            Gerhard

            • 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

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