Pixhawk and some ESCs with Low KV motors. Pixhawk is not the problem. Problem is related to ESCs, Firmware and fine tuning.

Posted by Pmarche on July 22, 2015 at 9:03am

I Found a solution to the problem; I changed ESCs to Tiger Motor ESCs and changed the signal to 200hz.

 

More tunning on PID required, will try Autotune, however quad flies great on stabilized mode.

 

 

It is now clear that the problem is not related to PIXHAWK but to the ESCs and  signal processing by the motors . As previously mentioned by experts in this Forum, the signal for Pixhawk is always the same and the controller is not the problem.

 

7/27/2015

 

Ok I accidentally sent a message to all the group, but I meant to make a clear declaration about PIxhawk.

 

For some reason, no one has ever found a resolution with the motor sync issue with some ESCs,( in my case with hobbywing 40a and 60a and the sudden loss of control of the Pixhawk  due to signal malfunction with low RPM high pole count motors  ( t motor 4008 380kv).

 

I believe it is important to mention, that after tunning, changing ESCs checking motors, and a few minutes of Stabilize and Loiter flight mode flight, switching to Pixhawk has been truly disappointing, and everyone should no that it will take some time to reach the " industrial" reliability and end user friendliness of the DJI Wookong M in the Pixhawk.

 

I believe it will be possible, but when there are potential to date unsolved issues, the community needs to be aware of them, in order to create proper expectations of Drone Builders and developers.

 

Pixhawk is completely incompatible with hobbywing Pentium 60 a and Hobbywing 40a ESCs. It Flips on necessary roll adjustments, and the motors are completely out of synchronization, even after adjusting RC signal parameters, PID adjustments, ensuring good connections, and checking motors and ESCs.

 

I truly hope the solution will be using DJI or T motor ESCs; however, there is a lot of people that are likely to try Hobbywing, or other brand high Amp ESCs with large motors, and my message is:

 

DON'T try it!!

 

You will spend more money, parts and time and brain power than simply using another controller.

 

 

 

 

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Replies

    • Fnoop > Gerhard Laubscher July 23, 2015 at 8:43am

      I built a tarot 650 sport as well (great frame!) with 3508 580kv motors and afro 20a slim ESCs (they fit neatly inside the arms).  When I was researching which bits I should get I came across a lot of references to this ESC sync issue, even with the same ESCs and motors that I was buying.  The consensus seems to be that the simonk firmware was designed for fast acro flying and has a very sharp throttle response and doesn't cope well with high pole/low kv large slow motors, and when full throttle is suddenly applied it can lose sync with the motors.  Applying settings to simonk that slows down the throttle response apparently helps, but a more reliable solution seems to be using blheli firmware instead.  So as soon as I got the ESCs I flashed them with blheli, did lots of testing, and had zero problems.  I've since had many, many hours of flying including many autotunes and fast/acro flying (well as fast/acro as a 650 with 14" props can be) with zero sync issues.  The blheli apparently has slower throttle response and doesn't suffer from the sync issues in the same way.

  • Crispin July 22, 2015 at 2:30pm

    it's not all bad...

    I had 6 HK 40A blue series with a pixhawk and it was impossible to fly with the RC Timer 360KV. Calm day, light on the throttle and it would be ok. Slight gust of wind, it would lose sync and crash.

    Simple fix - flash them with SimonK. I have hammered them and flown them hard in terrible conditions with a 6KG hex (frame + dead weight for testing) and they have not skipped a beat. 

    Flash them, takes 10 minutes, life is good.

    • Marc Dornan > Crispin July 22, 2015 at 2:45pm

      Crispin -- they are SimonK flashed already (Hobbywing 40A/60A). SimonK does not like low KV motors. Hence the issue.

    • Crispin > Marc Dornan July 22, 2015 at 2:57pm

      Most odd Marc. The Hobby King Blue 40A ones I had certainly did not like the low KV motors. I had read that SimonK also has problems but I read many people using them just fine.

      I flashed mine with bs40a.hex from https://github.com/c---/simonk_tgy3d

      I used the HK flashing tool which is well worth the money.

      If memory serves I used this tutorial.

      https://wiki.openpilot.org/display/WIKI/How+to+Flash+SimonK+to+ESCs...

      Because of the camera I have slung to the hex I thrashed it before putting the camera on as I did not want any surprises. I've flown it in winds gusting which had the hex at a serious angle trying to stay still. There is nothing that upsets the ESC / motor combo now. I would happy call it supported (simply because it works really well)

      I wonder what the difference is between the HobbyWing and Hobby King ESCs.

      c---/simonk_tgy3d
      tgy -- Open Source Firmware for ATmega-based Brushless ESCs - c---/simonk_tgy3d
    • Marc Dornan > Crispin July 22, 2015 at 4:03pm

      I think it really just depends on your specific motors. It is all a bit voodoo.

  • This reply was deleted.
    • arga firmansyah July 23, 2015 at 8:31am

      Just to make you aware, i'm using multistar 4225-390kv on 6s lipo with 13x6.5 prop along with ztw spider opto 30amp. I have had 2 crash due to esc failure. It was working perfectly great one day and then failed on the day after. 

  • This reply was deleted.
    • Marc Dornan July 22, 2015 at 1:00pm

      How sad! Best practice is to hot glue everything after it is connected.

  • This reply was deleted.
    • Pmarche July 22, 2015 at 11:24am

      Pedro, I will let you know how it goes with the T Motor ESCs; and If ever try Marc's solution, ( reinstalling firmware ) I will let you know. Thanks.

  • Marc Dornan July 22, 2015 at 9:11am

    This could be a SimonK Esc issue BTW. It does not play nice with low KV motors sometimes.Try flashing ESCs to BLHeli firmware. That may fix your issue.

    Before you do that: Are using the ground wires in the ESC PWM inputs? That is a known issue. I am sure you are. But if you are not, and just relying on the battery ground, that could also be an easy fix.

    And tie it down and torture the throttle to test before you try to fly it!!!

    • Pmarche > Marc Dornan July 22, 2015 at 9:24am

      By now, I have decided to try t motor ESCs, apparently they are designed to be used with these motors. I do not want to see another flip;

       

      When you say BLheli firmware, is it compatible with Hobbywing's ESCs? or is it part of ESC programming?

       

      Thanks a lot for your help!.

       

      I might re use those ESCs, have a total of 8.

      Yes I have the ground wire connected, the only missing wire is the power ( red ). I have seen quite a few videos on youtube, and after some adjustments, everyone keeps having problems.

       

      One of the problems,  is actually  the quad actually flights good in Stabilize and Loiter flight modes , until a sudden, drastic adjustment or movement in roll or pitch is executed. That makes the problem seem intermittent and solved, until you research the issue in depth and notice no one has posted a solution.

       

This reply was deleted.