I believe I have a problem with my Pixhawk and was hoping for some help. Also posted this on rcgroups.
The issue is that when my speed controllers are hooked up to the Pixhawk they exhibit a bad sync issue. However when they are connected to my old APM (3.1) or just a receiver directly they do not exhibit these symptoms. This has resulted in 4 crashes now until I just tonight narrowed down the issue to the Pixhawk.
Can anyone advise what is going on? Here are the specs of my setup:
Afro 30A ESC's with SimonK firmware (have tried all versions, and made my own with various parameters)
Tiger MT2216-9 1100kv motors
4S 3700mah battery
Replies
Hi Rob,
Xoltri isn't the only one, look at my post, pixhawk, sunnysky x2212 980kx and ... AFRO esc 30A
http://ardupilot.com/forum/viewtopic.php?f=80&t=5995 or
http://ardupilot.com/forum/viewtopic.php?f=80&t=6780
My fix was I changed the afro esc for esc32 controllers, all fine now.
Or change back to apm, no problems change back to pixhawk, crashed and sync errors,
Common thing by Peter, Xoltri and BobFlint ... Afro esc's
Hi Peter, maybe do you have a link e.g. to your esc32?
I have still the same issues with 3.1.3 RC1, RCTimer Opto 30A SimonK and TMotor 2216 with 900kv.
With reducing RC_Speed to 200 the issue was gone but that should be no good solution.
xoltri n'est pas le seul à avoir ce problème parce que j'ai le même problème. J'ai aussi ce problème et il ya beaucoup de témoignages sur rcgroupe similair et autre forum de rc.
I thought I read on another post that apm was against a 100hz 490Hz for pixhawk and now craig said that pixhawk works against a 400Hz 490Hz for apm??
I picture craig more aware and because member 3d robotics.
see it here: https://groups.google.com/forum/#!msg/drones-discuss/aR4g9sz9ssE/uK03OT6AEwkJ
Well, finally some good news! I decided to try modifying the RC_SPEED parameter and that seems to be the ticket. At 350 the problem is just as bad as the default 490. At 250 you can still hear a bit of a sync issue, but not as bad. At 100 it does not have the problem at all!
What's the effect of lowering this value, both in performance for my quad and in why it resolves my sync problem?
RC_SPEED set the rate the the ESCs get update. On APM it is 490Hz but Pixhawk maxes out at 400Hz even if the parameter is set higher.
Why the ESC works at 490Hz from the APM but needs a slower update rate from the Pixhawk is a bit of a mystery.
I appreciate the video but can you take some better pictures of your wiring arrangement so we can see how things are really set up.
Well, I braved a flight today with RC_SPEED set to 100 and it was a success. I flew around for 15 or 20 minutes, did a successful autotune and experimented with several throttle punches with no crashing. Log is attached.
This post from Rob_Lefebvre suggests that the stabilization loops are running at 100hz anyway so is there really a performance difference if RC_SPEED is also set to 100Hz? I don't know what it would fly like at RC_SPEED at 490Hz so I have nothing to go by.
Here are a few photos of the quad, an ADS-400Q. It is about an hour job to take the 'dirty' frame apart and put it back together so I'd rather not do that, unless there is something specific you want to see. It's not an odd or unique setup, it's a very standard quad. The 3DR power module connects to the power distribution board. All 4 speed controllers connect to that. I've clipped all of the 5v leads from the ESC's going to the Pixhawk, which is powered from the 3DR power module. Then, all of the ESC's are soldered direct to the motors. The only odd wire is the one from the power distribution board that goes to power the FPV gear via a 12v converter, but I had this disconnected during my youtube videos to save power. So that is not causing any issues.
That's really all there is to it. I can very reliably cause the issue again if I increase RC_SPEED past 250 or so. The only common thread I can think of on my setup is the high KV motors, as I've now tried 2 different Pixhawk's, tried two different types of speed controllers, 2 different power modules, but the only motors I have to try are a 1100kv and 2200kv. I think most use sub 1000kv motors on their quads.
Here are some pics.
Can you take one more end on where I can see the connections to the servo rail on the Pixhawk?
I'm trying to figure out where the tan, yellow, white, brown wires go
Sure, the yellow wires are the signal wires on all 4 motors. The White,Brown, and Tan are the ground. I used what I had hence the color mismatch. Sorry it's upside down. I can never get the orientation of photos right on this forum.
Thanks. It is still pretty difficult to see what is going on.
I don't know if you have a wiring error or if the ESC you have chosen is not compatible with the Pixhawk output.
I just spoke with Lorenz and he said if you send him some sample ESCs he will either confirm support or add support for them.
You can send them to me at the engineering address for 3DR in San Diego and we can have a look at them here.
>>>You could have an issue where the ESC is being knocked offline at some current draw levels or the PWM signal is not being interpreted correctly at some current draw levels because of a ground reference issue
Again, why not on APM and only Pixhawk? I literally did a straight swap in my video, everything stayed the same, and APM does not have the problem.
The weather isn't good for flying for the next couple days here, so I am willing to take my quad apart, and do a clear test. Power module soldered direct to esc direct to motor. I can take clear photos this way. But then if the problem is the same (and I'd be surprised and happy if it wasn't), then what? Would you then be willing to obtain one of these ESC's on your own for testing?
Also, on Mar 17 I received an email from Roger and it appeared that 3DR was going to investigate the Afro ESC's, what ever came of that?
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