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.
Replies
>>>You therefore already know that interfacing a 3.3 V logic (Pixhawk) to a 5 V other logic layer
RC receivers and ESCs are not 5V devices. Please see https://pixhawk.org/users/actuators/pwm_escs_and_servos
@Craig Elder Most ESC are 5V tolerant on their input and translating the 3.3V signals to 5Volts improve substantially noise margin.
In any case opto coupling is a much better solution than direct coupling to avoid noise ground coupling.
Couple of quick observations Gerhard:
Your ESCs are X-rotor 40a which are not Simon-K out of the bag (the Hobbywing 40a ESCs discussed at the start of this post are suggested to be Simon-K ones - The X-Rotor variant certainly are not, as they use SiLabs chipset which is not SimonK compatible). I use these same ESCs as you and the stock firmware works very well (although my Motors are Hobbywing x4113s 690KV on 4S, so not low KV) - even though they can be flashed with BLHeli firmware, I would not recommend it for a photography platform, as BLHeli can produce more heat and the benefits you get with it (such as damped light/motor braking) isn't of benefit where you need a very smooth flight profile. Also, the trip to BLHeli is one way as you don't get access to the manufacturer firmware to go back to it!
For landing gear, you can choose either a 2 position or 3 position switch. When binding your X8R do this in mode-4 (this is where you short signal pins 1-2 and 3-4 during the bind process (X8R usially comes with 2 jumpers in the pack to do this). It allows all 16 channels (as normal) on the sbus output, but allows channels 9-16 on the PWM (servo) outputs of the X8R. This way you can configure your radio in 16 channel mode, with channels 1-16 active, and say configure channel 16 for your landing gear (so assign the chosen switch in the mixer to ch16), you then connect the servo output from pwm output 8 (which is now ch16). Its worth noting that to power the landing gear, I would not recommend the 5v output from the X8R servo cable. I would suggest using a 5v BEC instead, otherwise the load applied to the servo rail could cause issues for your X8R.
I also have the x-cam gimbal the same as yours. I have had a serious lot of trouble with it as have others. Its presently back to HobbyKing and I'm waiting for a replacement, so good luck with that! There are a couple of discussions over on rcgroup about the issues here: http://www.rcgroups.com/forums/showthread.php?t=2261272
Cheers, Paul
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.
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.
Hi there,
It looks like you were able to resolve this issue by changing the signal. Did you make the change on the Pixhawk (if yes how?) or the ESCs?
We had a similar crash but our ESCs were already T-motor 40 Amp AIR ESCs. The discussion thread is at: http://discuss.ardupilot.org/t/pixhawk-crash-in-mid-air-after-flyin...
OK so my issue is "where do you go to see if your ESC/Motor combo is Pixhawk safe" ? Should be simpler then this.
Round 1: Afro 30A ESCs and sunnysky 3508s 700Kv motors -> no go
Round 2: Flash ESCs... better, damaged one of the ESCs during flashing -> go to round 3
Round 3: HK Plush 25A ESCs same motors -> no go
Unfortunately money doesn't grow on trees and trying various parts gets time consuming and costly. I know there are tons of other factors, but for some reason I never had problems with my good ol' APM 2.5X .
Just saying.
Crispin -- they are SimonK flashed already (Hobbywing 40A/60A). SimonK does not like low KV motors. Hence the issue.
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.
I think it really just depends on your specific motors. It is all a bit voodoo.
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