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

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.

Thanks Craig, but I am quite familiar with calibration procedures- on many flight controllers. The pixhawk is not that complex.

I have since reloaded the firmware- reconfigured all parameters and flight modes- recalibrated radio, accel, mag, and esc's.... and I am right where I started.

This quad was fine. Now it will barely get off the ground, and acts as though it is severely underpowered. I was getting 17 minutes prior to the esc calibration that sent this whole build into the weeds.

I am one day from tossing the pixhawk and the entire product and it's peripherals in the trash heap. I despise DJI, but I have projects and upcoming work- I can not spend inordinate amounts of time blindly troubleshooting.

The only thing I can say is, my ch 6 is still set for pitch and roll rate P and if I drop it all the way down to the lowest setting I can get off the ground a few inches. If I leave it set at max it won't even lift the landing gear in the air.

After almost 2 years of flying and no problems, I am frustrated that this little thing has turned me against the pixhawk. Shame. I am not the most knowledgeable builder, but I am pretty well versed and I have spent a lot of time with the pixhawk. I am very comfortable with mission planner and droid planner, but I can't find a solution- I cannot even get back to where I was before the snafu.

Replies

Jason Franciosa July 27, 2015 at 11:53am

I am running a 1300mm quad with 28" props on 110KV Motors on 12s. KDE 7208 and KDE 75 amp HV ESC's and can not get it to work.

Had 3 crashes now, all after a yaw input and am completely stumped. It's like the motors dont respond fast enough and then it wobbles and flips.

Here's the info and logs: Any help would be great.

http://ardupilot.com/forum/viewtopic.php?f=111&t=12758
- Jason Franciosa > Jason Franciosa July 27, 2015 at 1:27pm
  
  Solved. ESC Sync issue. I didn't think KDE ESC's with KDE Motors that are rated for 12s together would have problems, but, sure does. Maybe the newest version can handle 12s, but, the 75HV ESC's with 110kv 7208 motors do not work on 12s.
- Jesus A > Jason Franciosa September 18, 2015 at 9:51am
  
  Hi Jason
  
  So what cell count are you finally using?
  
  Do you find the motors as efficient and agile as advertise?
  
  I am really considering them
Rob_Lefebvre July 27, 2015 at 7:59am

I've built several multirotors, and have yet to run into a sync problem. I'm not entirely sure why that is, but I like to think it's due to proper construction techniques (using the signal ground wire long before it was accepted as being required by the wider community, etc. ) and also not using SimonK or BLHeli.

My secret? Hobbywing ESC's on the standard firmware, which is excellent. I have a large Octo running 320kV motors on 6S with HW 40a X-rotor ESC's, as well as a quad on 515kV KDE motors and HW Quattro 25A ESC. Never a problem. Also recently helped somebody get a large X8 flying with T-motors and T-motor ESC's running 18" props, no problems there either.
- Henri > Rob_Lefebvre July 29, 2015 at 11:54am
  
  @Rob_Lefebre I like your secret. (Hobbywing)
  
  I like what I see about the "advertised performances" and I'm going to try them out.
  
  Thank you, Rob, for sharing your positive experience.
  
  This manufacturer mention on the HV80 Pro:
  
  -- Quote
  
  " The twisted-pair design of the throttle signal cable effectively reduces the crosstalk produced in signal transmission and makes flight more stable."
  
  Compatible with various flight-controllers and supports a signal frequency of up to 621Hz (Notes: all throttle signals over 500Hz are non-standard signals.).
  
  -- End of quote
  
  I'll try a number of different large pancake motors with it.
  
  (Currently using Turnigy dlux 80A opto)
  
  Again thanks Rob.
  
  Henri
- Pedro de Matos > Rob_Lefebvre July 27, 2015 at 8:51am
  
  good, good thing they were lucky.
  
  Because I do not, I suppose that will be the frimware, I see no other solution.
  I have:
  - T-ENGINE AIR GEAR 350 Set (920kv)
  - ESC AIR20A 600Hz
  
  and simply Pix, does not transmit any power to the ESC. it does not fly.
  
  I have tested the mission planner with the joystick and is the same.
  
  I did everything as stated, calibrations, links, everything ... and nothing, simply does not fly. But it works well, alloy gun disarms, just do not have rotation to fly.
  
  I'm sad without solutions to the head. :(
- Muhammad Abdul Hadi > Pedro de Matos July 28, 2015 at 9:17pm
  
  bro, I read elsewhere that one guy finally checked THR_MAX and found that somehow it was too low, try checking that too.....good luck
- Hiway > Rob_Lefebvre July 27, 2015 at 8:50am
  
  Rob,
  
  I never had a problem with my quadrysteria (blue series) 40 amp simonk esc's... until now. I am at a total loss on why a simple esc calibration would send my entire project into a tail spin. I cannot figure it out. I have never had any issues with the pixhawk- love it. My hex was reliable and excellent for AP and mapping use with droid planner- if it weren't for me missing the worn stitching on the lipo strap which gave way and caused the battery to literally drop off the craft, I would still be using it. I had well over a hundred flights with it. I sent it on autonomous mapping chores regular with nary a hitch.
  
  I posted in this particular thread mainly because it offered the closest description of what I was experiencing.
  
  I am going to just reload the firmware and begin again. I was hoping someone would come in here and offer a basic solution that I just missed. If it would have occurred in almost any other way, then the crash of the hex would have been blamed and I would have just thought the pixhawk was faulty. But I have been flying and tuning this recent quad for a week before this happened. Complete mystery.
- Developer
  
  Craig Elder > Hiway July 27, 2015 at 9:05am
  
  I would re-do the ESC calibration first. Some people forget / are not familiar with using the Safety button to calibrate the ESC. Look at the video on calibrating the Iris ESC on the 3DR you tube site. It will give you step by step instructions.
- Hiway > Craig Elder July 27, 2015 at 9:41am
  
  Thanks Craig, but I am quite familiar with calibration procedures- on many flight controllers. The pixhawk is not that complex.
  
  I have since reloaded the firmware- reconfigured all parameters and flight modes- recalibrated radio, accel, mag, and esc's.... and I am right where I started.
  
  This quad was fine. Now it will barely get off the ground, and acts as though it is severely underpowered. I was getting 17 minutes prior to the esc calibration that sent this whole build into the weeds.
  
  I am one day from tossing the pixhawk and the entire product and it's peripherals in the trash heap. I despise DJI, but I have projects and upcoming work- I can not spend inordinate amounts of time blindly troubleshooting.
  
  The only thing I can say is, my ch 6 is still set for pitch and roll rate P and if I drop it all the way down to the lowest setting I can get off the ground a few inches. If I leave it set at max it won't even lift the landing gear in the air.
  
  After almost 2 years of flying and no problems, I am frustrated that this little thing has turned me against the pixhawk. Shame. I am not the most knowledgeable builder, but I am pretty well versed and I have spent a lot of time with the pixhawk. I am very comfortable with mission planner and droid planner, but I can't find a solution- I cannot even get back to where I was before the snafu.

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