Hello all,
Up until today I was blissfully ignorant of the potential problems of using SimonK flashed ESC on larger multicopters with high pole count low kV motors. Maybe others know about this, but I did not. I was browsing the forums and came across this:
https://groups.google.com/forum/#!topic/drones-discuss/tq8l52cwGXg[1-25-false]
I decided to try and reproduce this on my quad. I was shocked to find how easy it was to get the motor to briefly un-sync! Here is a video of me tilting the quad around in stabilize with only 1 motor connected:
https://www.youtube.com/watch?v=9mbfMWBkNX8
My setup:
Ironman 650 quad
Multistar 690 kV 22 pole motors
4S 5000 mAh battery
12X3.8 APC props
Afro 30A ESC's with the original firmware untouched
Genuine 3DR APM 2.5.2 with 3.1 firmware
Keep in mind I have been flying my quad for 6 months with no issues. Flys great, although I have not flown it in much more than 10 mph winds. This concerns me greatly though.
The motors go unsynced for only an instant and appear to always recover immediately. I *hope* this means it will not crash from this in flight.
My questions to anyone that may have more knowledge of this situation:
1. I read Marco say that the 2012-09-30 SimonK firmware worked better concerning this problem. Is there a change log anywhere of the different firmwares? Does anyone know what changes were made specifically that improve or worsen this issue?
2. Am I tempting fate by continuing to fly my quad like this?
3. What ESC, or firmware, should I run to avoid this?
Thank you! I am scheduled to do some aerial photography this weekend for a group and was ready to go until I read this... now I am nervous. Any insight is much appreciated.
Replies
Update!
I found a person on RCgroups discussing his same problems with the same motor / ESC combo. He alluded to resolving it by advancing the timing. I sent him a PM and he kindly sent me the .hex file that he used. This saved me a lot of time experimenting with modifying the timing in small amounts.
Just flashed it into all 4 ESCs and it seems to work great! No sync problems. Did a test flight and everything went well too.
For anyone curious, this was his message outlining the few changes:
"If you use older firmware re compile it and flash it with a bit more
advance of about 24 degrees and lower frequency.
Also in the file "tgy.asm" change the line that says:
POWER_RANGE = 800 * CPU_MHZ / 16 + MIN_DUTY
to
POWER_RANGE = 1200 * CPU_MHZ / 16 + MIN_DUTY
Attached is the newer version ready compiled with the required changes"
David,
I have attached the .zip file that was given to me and 99% fixed my issues. Flash the afro_nfet.hex to the controller (I use the KKflashtool for this and the Afro USB dongle).
I have not diff'ed the two versions, but this was the message given to me:
Make sure to flash the correct version or the board can be damaged!
Good luck.
tgy_new[1].zip
I did some more reading about BL heli. Looks like your answer. The Demag compensation is particularly intriguing. As I understand it, you can use the Afro USB tool to flash this easily, too.
Here's an excerpt from the manual:
Humm, sorry it didn't work out. For me, once I updated, I was able to get it only very slight out of sync when I gave the most extreme inputs. I deem it safe to fly and have flown it in 30+ mph winds with no ESC trouble. Granted, that was with 690 kV motors, maybe your motors are more finicky.
Sounds like you should give BLheli a try.
Cheers,
why don't you try different Timing settings (google on how to do it, we had to recompile it)
We have fried couple of pancake motors this way, going out of sync.
The latest SimonK firmware does much better then the firmware that comes on the Afro Esc's stock. I still had issues with syncing with the latest but I am running 580kv motors.
I chose to flash blheli on them as it is easier to change the settings which can be done after they are flashed through the servo cable. I had to change the settings to be demag to off and timing at medium-high.
You could try building simonk from source with different settings and flashing it to test. While you might be alright to continue flying I don't think I would until I know for a fact there are no more sync issues. All it will take is a strong gust of wind or a fast maneuver causing one or more motors to ramp up fast enough and go out of sync. As long as it recovers fast enough it might be alright or if it doesn't recover fast enough then it will go down.
Hi George,
Thank you for the advice. I have a spare controller, maybe I will try flashing the latest Simonk firmware on there tonight and see if it improves.
I am familiar with how to flash using the KKmulticopter flash tool and the Afro USB programmer. Maybe a stupid question: Can I use this same programmer for flashing the BLheli firmware?
Cheers,
With the latest version of BlHeli Suite I believe you can flash blheli firmware using the servo cable and usb linker. It will maintain the simonk bootloader so you could always switch back to simonk wihtout having to flash using the isp pads.
I flashed all mine using the isp pads because my usb linker wasn't working right. I also overwrote the simonk bootloader so if I want to switch those back I will need to undo the shrink wrap again and solder wires to the isp pads.