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Pixhawk DJI ESC Issue

Posted by mark bellncula on September 21, 2016 at 1:25pm

There is a known incompatibility issue with Pixhawk FCs and DJI Tuned Propulsion Systems. And I have seen various solutions online in multiple forums, including this one. Problem is, some of those solutions are months and even years old and the info is incomplete. All I'm looking for right now is consensus on how to resolve this known issue. Here's some background on the subject.

I have two UAV's built on Flywheel 450 DIY clone kits, each with a Pixhawk PX4 running 1.4.1dev. Both fly fine with the cheap clone kit parts, but they are not very resilient. I have had multiple motor failures while in the air. I understand that's what you get when you buy cheap parts. So in an effort to upgrade I got a DJI E310 Tuned Propulsion System from the brick and mortar Multicopter Warehouse shop in Castle Rock Colorado (they are investigating this issue for me, as well).

The core of the issue is that the 420S ESC that come in the E310 kit are already "tuned", so you are supposed to skip that step, as stated here;

http://ardupilot.org/copter/docs/esc-calibration.html

So, I did indeed skip that part, and my UAV now flips when given enough throttle for take off. I triple checked, everything is spinning properly, motors and props.

Obviously the ECS need some sort of calibration, or the throttles have to have their PWM values manually set. I'm really not sure.

Now in investigating the issue online I see that there are a lot of people experiencing the same issue and they have come up with the flowing solutions.

  1. Stop using a Pixhawk and get a DJI Naza-M and be done with it. 
    • That solves the immediate issue of getting the UAV up in the air, but it doesn't take into account all my proprietary custom accessories that run off the Pixhawk. I have to be flying on a Pixhawk.
  2. Flash those 420s ESCs with firmware that works
    • I have seen a couple of posting where they claimed this works. but when going to the link the link is missing, 404. What firmware is working, where do I find it and how do I flash it?
  3. Just get new ECSs with known compatible firmware.
    • Sure, but I hard soldered in those ESC to the PDB and all that hard work, time and money will be lost... which is frustrating. There's has to be a simpler, less frustrating, solution. 
  4. Manually set your throttle PWM values to 1000min and 2000max.
    • I have seen this mentioned but I haven't seen anybody confirm that this solved their issue.

Is anybody familiar with this issue and know of a solid fix, something I haven't herd of, or one of the ones listed above?

Any practical insight will be helpful.

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Replies

  • Alexey Dobrovolskiy April 4, 2017 at 5:31am

    Hi,

    we have quite good experience with DJI propulsion systems with Pixhawk autopilot + ArduCopter firmware. ~25 copters and we are building 20 more for drone dances.

    Modern DJ ESC's don't support calibration, they have fixed working PWM pulse width range. For example E2000 has 1120 to 1920 μs (http://www.dji.com/e2000/info). It seems that all latest DJI ESC have the same range.

    If you will not set right ArduCopter parameters your bird can flip over (especialy in case of automatic take-off) just after take-off because autopilot will send too low PWM to regulators. Part of motors will produce enough lift, part are not.

    To prevent this you need to set next values (for E2000 but I think they should work for all ESCs):

    - MOT_PWM_MIN = 1120

    - MOT_PWM_MAX = 1920

  • Troy Gamm April 3, 2017 at 5:20pm

    Hi Justin, yep, it works aside from the issue with the motors not spinning the same RPM initially and wanting to roll over until it gets airborne.  I will have to try the MOT_SPIN_Armed, THR_MIN and the MOT_PWM.  

    The only issue I had that resulted in the motors not spinning was due to me being a newbie.  I am using a Taranis X9D and one of the settings in the TX Companion had one of the two position switches setup to override the Throttle.  It only took me a few hours to figure that one out and then the motors spun right up.  

    I have RTFhawk version.  I did have an issue where the case opening on the end where the ESCs plug in didn't allow the keyed connectors from the ESCs to plug in right side up so I had to trim the case.  Without trimming the case, the ESC connectors would only fit upside down.

    I have verified they are all wired correctly and spin the correct direction.  

    After I get it up in the air, it flies really nice.  I wish I had some advice for you to get those things spinning.

    Justin said:

    Troy, your setup works?! I'm using the E310 as well and my motors won't even spin. Did you have this issue at any point? I used the ESCs and motors with the original naza setup, so I know they work(ed). I've set my MOT_PWM to multiple different values as recommended by several posts I've read and nothing changes. PixHawk arms fine, but no motor spin. Tried the motor test from mission planner, all I get is multi-color LED with a tone from PixHawk and no msg in mission planner. If anybody has suggestions, please let me know. I have no idea at this point in the process as to what might fix it.

    Troy Gamm said:

    I have the same basic setup except I have the hex version DJI F550 frame, Pixhawk and the DJI E310 tuned system. I haven't heard of the incompatibility but it could explain the odd way every flight starts for mine. Right after arming, when I give it just a small amount of throttle, there are usually 1 or two motors that spin noticeably slower than the other 4. As I give it more throttle to take off, you can see it tipping toward those slower motors. I have to manually apply ail & elev to counter its slight tipping until I get it airborne. After she is in the air, it flys pretty well and doesn't seem to have an issue at all. Even though I haven't run the in flight auto tune, it is a very stabile platform and loiters rock steady. If I didn't control the leaning during liftoff, it would flip right over. I just got used to it but it drives anyone I let fly it crazy the first time they attempt the takeoff.

    My guess is that this might be related to the stated incompatible issue you mentioned. I would love for this to be solved.
  • Fnoop April 3, 2017 at 12:39pm

    I have the E300 propulsion set which works perfectly with pixhawk and arducopter.   Have you tried arducopter?  The E300 was a fantastic starter kit, they are perfectly tuned esc/motor set, have great flying characteristics and long flying time.  They don't need any calibration (can't be calibrated) and last time I looked the ESCs couldn't be flashed.  It would be a shame if DJI made these deliberately or otherwise incompatible with other flight controllers.

    I also used afro slim 20a ESCs with the E300 motors which worked perfectly.  But as you say would be a shame to not use the DJI ESCs which are very good.

  • Will Masters April 3, 2017 at 12:04pm

    I have the e800 tuned set (3510/350 motors; 620s ESC) on a custom quadcopter frame w/ pixhawk. I had a bunch of trouble getting everything to work at the very beginning but it's awesome now and worth the frustration (all the problems I had ultimately due to user error...). Steps to troubleshoot:  
    1. Are you able to connect to the ESC using DJI ESC assistant? Does everything show correctly and updated? Let us know if ESC assistant shows any problems. 
    2. Check your motor mount screws - if they're too long, even barely, they can mess with the wire leads to motor coils and cause all kinds of problems including preventing the motors from starting (ESC doesn't recognize motor correctly).
    3. Quadruple check your ESC>Pixhawk connections. I kept flipping at takeoff and was absolutely positive that my wiring was correct. I was wrong; flipping at takeoff is indicative of your ESC's being connected in improper order or motor(s) spinning in wrong order. Check, look at motor map, check again...
    4. I haven't experienced this problem but other's have - cable extensions between motor & esc can prevent arming. ESC doesn't correctly recognize motor so it won't start. Either mount the ESC closer to motor or you can try to increase wire gauge of extensions. 

    5. When some motors spin slower/faster than others after arming, you can normally fix by changing values for MOT_SPIN_ARMED or THR_MIN (depending on version). Increase to point where all props spin equally but quad stays on the ground. 

    Good Luck

  • OG April 3, 2017 at 12:04pm
    Hello,
    Please understand the ESC that come with your DJI kit is for DJI FC only will not work with the Pix hawk firmwear ! You may need an ESC that works with both DJI and Pixkawk !

    http://mymobilemms.com/OFFTHEGRIDWATER.CA/ESC/4-in-1-Speed-Control-...
    4-in-1 Speed Control Quad HOBBYWING Skywalker Quattro 25A x 4 [SW25A4IN1] - $40.13 : OFFTHEGRIDWATE…
    OFFTHEGRIDWATER.CA 4-in-1 Speed Control Quad HOBBYWING Skywalker Quattro 25A x 4 [SW25A4IN1] - Features: RELAPSED BY Xrotor 20A Speed Controller for…
  • Justin April 3, 2017 at 1:07am

    Troy, your setup works?! I'm using the E310 as well and my motors won't even spin. Did you have this issue at any point? I used the ESCs and motors with the original naza setup, so I know they work(ed). I've set my MOT_PWM to multiple different values as recommended by several posts I've read and nothing changes. PixHawk arms fine, but no motor spin. Tried the motor test from mission planner, all I get is multi-color LED with a tone from PixHawk and no msg in mission planner. If anybody has suggestions, please let me know. I have no idea at this point in the process as to what might fix it.

    Troy Gamm said:

    I have the same basic setup except I have the hex version DJI F550 frame, Pixhawk and the DJI E310 tuned system. I haven't heard of the incompatibility but it could explain the odd way every flight starts for mine. Right after arming, when I give it just a small amount of throttle, there are usually 1 or two motors that spin noticeably slower than the other 4. As I give it more throttle to take off, you can see it tipping toward those slower motors. I have to manually apply ail & elev to counter its slight tipping until I get it airborne. After she is in the air, it flys pretty well and doesn't seem to have an issue at all. Even though I haven't run the in flight auto tune, it is a very stabile platform and loiters rock steady. If I didn't control the leaning during liftoff, it would flip right over. I just got used to it but it drives anyone I let fly it crazy the first time they attempt the takeoff.

    My guess is that this might be related to the stated incompatible issue you mentioned. I would love for this to be solved.
  • Troy Gamm April 3, 2017 at 12:35am
    I have the same basic setup except I have the hex version DJI F550 frame, Pixhawk and the DJI E310 tuned system. I haven't heard of the incompatibility but it could explain the odd way every flight starts for mine. Right after arming, when I give it just a small amount of throttle, there are usually 1 or two motors that spin noticeably slower than the other 4. As I give it more throttle to take off, you can see it tipping toward those slower motors. I have to manually apply ail & elev to counter its slight tipping until I get it airborne. After she is in the air, it flys pretty well and doesn't seem to have an issue at all. Even though I haven't run the in flight auto tune, it is a very stabile platform and loiters rock steady. If I didn't control the leaning during liftoff, it would flip right over. I just got used to it but it drives anyone I let fly it crazy the first time they attempt the takeoff.

    My guess is that this might be related to the stated incompatible issue you mentioned. I would love for this to be solved.
  • Justin March 29, 2017 at 1:48pm

    Mark, any updates? Did you find a realistic solution to the E310 ESCs?

  • Junayed Hossain September 29, 2016 at 10:03am

    going through the same issue, following..

  • Roberto Tascheri September 22, 2016 at 3:44am

    Id love to know... going thru that road right now, curiously I havent even unboxed, and yet the post is one day old.... its a sign, ha. 

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