Motors loosing synch?

Info and Discussion about the ESC32 hardware and software

Motors loosing synch?

Postby DUKE40 » Tue Sep 23, 2014 3:01 pm

Hi,

today I wanted to make the maiden flight with my new copter, but everytime after a few seconds in the air one motor stopped running and the quad flipped.
The issue did not occur each time on the same motor, but occured on all 4, so it is not an issue concerning one motor or one ESC.
All ESC32 have been calibrated with the motor and prop (T-Motor MN3510-15 and T-Motor 12x4).
I performed the current limiter calibration with 15A maximum with no issue.
I then performed the RPM to Voltage calibration without any issue as well.
esc32-MN3510-T-Mot12x4-15A.txt
(911 Bytes) Downloaded 170 times


Any idea what is wrong and causing the issue.
All ESC32 are controlled via CAN bus.

It looks like the motors are loosing synch, but I have no idea why, I did not even push the throttle, I was always taking off very gently pushing the throttle stick very carefully. Fortunately I never got very high as that stage and nothing happened to the Quad as it only fall from les than 50cm.

It would be great if somebody could give me some hint, what I need to check and how I can isolate the root cause of this issue.
Best regards,
Image
Spacewalk 550, MT2216-11, SimonK 20A ESC, AQ6 DIMU, 10x5" CF, SJ4000
CamCruiser, MN3510, ESC32, AQ6 DIMU, 12x4" CF, SimpleBGC, GoPro Hero 3 BE
DUKE40
 
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Re: Motors loosing synch?

Postby JussiH » Tue Sep 23, 2014 3:40 pm

You need to verify that your current limiter params CL1 - CL5 allows the motor to ramp up without loosing sync. The easiest way to do this is to use the DUTY command over UART to go from a low ESC duty to a high Duty in a single timestep. If your CL terms iscalibrated correctly, it should allow you to start the motor and then go to full duty without loosing sync.

:!: BE VERY CAREFUL AND MAKE SURE THE COPTER IS SECURELY STRAPPED DOWN BEFORE PERFORMING THIS TEST. YOUR MOTORS WILL RUN UP TO FULL SPEED :!:

Connect via Putty or similar with 230400 8N1

Code: Select all
Arm
Start
Duty 100


Alternatively you can hook a servo tester, and then crank that up very fast to see if the motor looses sync. If it does, you need to redo the CL calibration at a lower limit.

This article describes how the Virtual Current limiter in ESC32v2 works:

http://autoquad.org/wiki/wiki/esc32/esc ... libration/
JussiH
 
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Re: Motors loosing synch?

Postby JussiH » Tue Sep 23, 2014 11:10 pm

Saw your post on the Camcruiser thread.

You should understand that there is an important difference between what the motor demands on fast ramp of duty and what it needs to run the motor at steady full speed. Ramps is governed by the Virtual current limiter (which you calibrate with the CL calinbration) and the overall current limit from the main settings governs the maximum total current that the ESC can source.

If you allow the motor 12A or 13A in the CL calibration, I bet you will find that you can still get 20-25% throttle increase in a single timestep. Thats more than enough to stay stable and way better than most other ESC´s you will find in the market. And even if more than 25 percent increase is demanded in a single timestep (1/400 sec), all that happens is that the virtual current limiter will smooth the increase to happen over 2 or more timesteps to keep the ESC from loosing sync.

That same motor that will only allow a CALIBRATION limt of 12-13A or lower may still require 15-20A overall limit to run at full speed.
JussiH
 
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Re: Motors loosing synch?

Postby DUKE40 » Wed Sep 24, 2014 5:37 am

Hi Jussi,

I am not sure I correctly understand what you mean.
Do you mean I should run the current limiter calibration with a lower limit like 12A or 13A and in the configuration in the field Max Current of the section General ( value MAX_CURRENT of the configuration file set something like 15)?
Best regards,
Image
Spacewalk 550, MT2216-11, SimonK 20A ESC, AQ6 DIMU, 10x5" CF, SJ4000
CamCruiser, MN3510, ESC32, AQ6 DIMU, 12x4" CF, SimpleBGC, GoPro Hero 3 BE
DUKE40
 
Posts: 364
Joined: Tue Mar 26, 2013 9:49 pm

Re: Motors loosing synch?

Postby JussiH » Wed Sep 24, 2014 9:54 am

Yes, Exactly.

Run the CL calibration at a lower amperage. That will take care of the ramps.

When you run the CL calibration, the "CURRENTLIMITER_RESULT.txt" file will show you the max RPM and max Amperage of the motor at full speed. You then set the overall limit a little higher than this number.´

That will give you a motor that is able to ramp up without loosing sync and still allow you to run the motor at full speed - best of both!
JussiH
 
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Re: Motors loosing synch?

Postby bluuu » Wed Sep 24, 2014 4:28 pm

Duke: set advance to 19-25 and check again
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Re: Motors loosing synch?

Postby DUKE40 » Wed Sep 24, 2014 7:18 pm

Hi Bluuu,

do you mean I should test with values for advance in the general section of the ESC32 configuration ranging from 19 up to 25?
I will test that as well, as soon as I get time.
Best regards,
Image
Spacewalk 550, MT2216-11, SimonK 20A ESC, AQ6 DIMU, 10x5" CF, SJ4000
CamCruiser, MN3510, ESC32, AQ6 DIMU, 12x4" CF, SimpleBGC, GoPro Hero 3 BE
DUKE40
 
Posts: 364
Joined: Tue Mar 26, 2013 9:49 pm

Re: Motors loosing synch?

Postby bluuu » Wed Sep 24, 2014 7:31 pm

yes

For the first, try at 15 but for larger motors (like 3510) probably about 20
bluuu
 
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Location: Poland, Silesia

Re: Motors loosing synch?

Postby DUKE40 » Sat Sep 27, 2014 8:44 pm

Hi,

I just performed a test, changing the advance to 20 and then connecting using PuTTY and perform right after arm and start a duty 100, I had no synch problems, the motor turned full speed almost immediately.
So it seems this was enough for solving my problem.
For safety, I have performed another calibration with a lower number for the current limiter (13A) and performed again the rmptovoltage calibration with the new CL values, just in case changing the advance param would not be enough on the copter.
Luckily I have a test environment with exactly the same ESC, motor and prop, so I do not need to either disassemble the copter or perform those tests directly on the copter.

Will se on Tuesday if the copter is willing to make the maiden flight.
Best regards,
Image
Spacewalk 550, MT2216-11, SimonK 20A ESC, AQ6 DIMU, 10x5" CF, SJ4000
CamCruiser, MN3510, ESC32, AQ6 DIMU, 12x4" CF, SimpleBGC, GoPro Hero 3 BE
DUKE40
 
Posts: 364
Joined: Tue Mar 26, 2013 9:49 pm

Re: Motors loosing synch?

Postby aBUGSworstnightmare » Sun Sep 28, 2014 7:28 pm

Hi DUKE40,
have a look at my data for this motor with Graupner e-Prop; you should be able to use a little less agressive timing settings for the T-prop.
Joerg
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