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.
- 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.
- 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?
- 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.
- 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.
Replies
hello,
actually this is not a new issue ! this is not the pixhawk issue either it is the ESC problem! the issue is firmware Blheli is know to work and work well so you should use Blheli if you want no issues ! as well as hobby wing OEM firmware! the Simon-k works best with DJI and has known issues with Pix Hawk! Kiss ESC also known to have issues as well as meany other well known ESC , you would expect to work but do not ! meany threads on this matter in the past please look ! first you need to know what version of the firmware your running! just because it works for some and not others indicates it it most likely a ESC firmware issue...
you can try to re flash the ESC but what is the working firmware version for the ESC , do you have a re flashing tool ?
better to scrap the E300 ESC use ones with BLheli software/firmware.
Do we happen to know in general terms what the underlying factor is?
1.) Pixhawk is commanding an rpm that isn't being delivered on one or two motors?
2.) Pixhawk is commanding a slower speed on one or two motors for an unidentified reason and then doesn't react quick enough on takeoff to prevent tipping over?
3.) Pixhawk is reacting quick enough to speed the motor up to keep it from tipping over but the ESC isn't reacting quick enough.
4.). We have no clue as to why this is happening.
Since this a highly reproducible issue but is completely resolver the second it is in the air leads me to believe it is not #1 or #3 above. Do you think the ardupilot developers are aware of the issue and are working on it?
I rally appreciate the help from you guys. I can be a bit obsessive about getting things to work the way the should and that prevents me from just overlooking the issue and just compensating with roll and pitch inputs during the takeoff to prevent the tipping.
Thanks,
Troy
ps - please do persevere. a) It would be great to get the newer DJI ESCs working - the older ones worked perfectly, and b) they're great ESCs/motors, don't throw them away :)
The motors should work perfectly with other ESCs, at least I used the E300 motors with other ESCs with no problems.
Fnoop said:
Just a quick note - this isn't a 'pixhawk' problem - the pixhawk is a bit of hardware. It's a problem with setup of the software/firmware (px4/ardupilot) to work perfectly with these ESCs at the bottom end of the thrust range, which is quite a complex setup, at least in arudpilot there are various parameters to be tweaked.
If you're using ardupilot, suggest you join this post:
http://discuss.ardupilot.org/t/pixhawk-with-dji-e310-help/16193/2
If you're using px4, suggest you post wherever they post. Not many folks hang out here any more.
I really want a setup that is extremely reliable in the motor performance (stabil, smooth, etc.). For that reason I think I am going to purchase new ESC's to replace the DJI 420s that came with my E310 kit. I am looking at the dsy 40A with Blheli, oneshot125. I know getting 40A is WAY overkill for my F550 but I am looking to switch to a larger frame later this year and I figure those ESCs would have me covered.
Would these or any other non-DJI ESC work with the DJI 2312 motors or do I need to change the motors as well? If they won't work with the DJI 2312 motors, does anyone have any suggestions?
Thanks!
Troy
Thanks Alexey. I will give it a try. I really I wished I understood the underlying problem better as too why the problem exists in the first place.
Troy
Please check also MOT_SPIN_MIN value. By default it should be 0.15, you can increase it up to 0.30. I hope that your bird will not take-off with 30% of maximum thrust...
Well, I really wish Alexey's post would have fixed this issue but it did not. I do believe his PWM numbers are correct as I tried different minimum settings below 1120 and none of them worked. Once I set 1120, all of the motors spun after arming and all about the same speed. Where the issue came is when I would increase the throttle to take off. No change here. Usually only one motor would be running at a lower RPM but sometimes it would be two. As I increase the throttle slowly to take off, you can see that one motor is definitely slower than the others. If I keep increasing the throttle slowly, eventually the copter leans into the slower motor. If I keep increasing it slowly, it eventually tips into the ground on the side of the slow motor. I have found that if I rapidly increase the throttle, it resolves itself and takes off straight up. The issue becomes even more strange in that it looks like it would resolve itself after a minute or two of aggressive flight. If I fly it pretty aggressively for a minute or two, land it then attempt a take off while advancing the throttle slowly, it works fine. But if I just fly it nice and mellow, the problem persists.
It would be awesome to figure this out. Otherwise, I may have to end up replacing the ESCs. Does anyone have any idea of why the Pixhawk would be different than say a Naza where the motors are concerned?
Thanks Alexey! I will give this a try today and hopefully it will fix the issue. I have not been able to accomplish any automatic flights for this very reason. The copter flips on takeoff.
Thanks
Well, it looks like somebody figured it out.
I did eventually solve the ESC calibration issue by using cheap generic 20a ESC that I had leftover from a previous build.
But yes, it sounds like I had the same issue with the DJI ESCs/pixhawk that the rest of you guys appear to have, flipping the bird on take off.
But with the generic ESCs all the Pixhawk power and arm protocols are there, the four beeps and the low throttle spin at arming.
The DJI motors are great and everything on this build is working as it is supposed too, so I'm going to stick with it.
Cheers!
_M
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