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Position halten stabilisieren

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Foersom meinte
Domino meinte
I am using Afro-ESC 30A 6s.

That is fine. When you use PWM, have you calibrated each ESC? I have heard that is necessary.


I am using I2C, not PMW. Did not calibrate them, but they run fine, I think.

Foersom meinte
Magnetwerte is what is called Field (Percent) in the telemetry, some places also called EarthMagnet. If you have no Graupner or Jeti RC transmitter with telemetry you can use the simulated telemetry on the MK Tool scope (main) window. Did you see the MagnetField in the GPX log?


Didn't chek the gpx-log myself, just live data. but might do that...

Foersom meinte
I recommend that you read the whole page about magnet-error. Perhaps it is not the source of your problem, but then we avoid confusing information here.


I didn't have a magnet error anymore since I raised the compass.

Foersom meinte
Take off your propellers, run motor test and see if magnet field changes when motors are running fast.


Will try that.

Foersom meinte
Disconnect the external compass, then you know for sure the internal compass is used.


Good idea.
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Domino meinte
I am using I2C, not PMW. Did not calibrate them, but they run fine, I think.

Then calibration is not necessary, because I2C provides a digital value, whereas PWM is like an analogue (time) value.

However your hexa-copter design might be the cause of the I2C errors, because you have the "fragile" I2C signal going out to the end of each arm. Inside each arm the I2C cable is parallel with (electric noisy) power cables and that can by magnetic induction cause noise in the I2C signal, which will cause I2C data errors. Keep this in mind if you encounter I2C errors.

You already know about the magnetic induction because by now you have read the whole page about magnet errors and seen the videos.

How have you connected the I2C signal from FlightCtrl to the 6 ESCs? Do you use some sort of I2C isolation board to separate the I2C going to each arm or are they all just connected in one central point?
« Bearbeitet von Foersom am 12.04.2016 11:08. »
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How have you connected the I2C signal from FlightCtrl to the 6 ESCs? Do you use some sort of I2C isolation board to separate the I2C going to each arm or are they all just connected in one central point?


I am using a mini 8 distribution board for power and for the i2c distribution to all ESCs. The board is connected to the FC via the standard molex cable.

Maybe I'll have to consider using centralized ESCs again? The advantage of the ESCs out on the arm is the cooling effect from the rotors.
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I am using a mini 8 distribution board for power and for the i2c distribution to all ESCs. The board is connected to the FC via the standard molex cable.

Does the I2C distribution board have any electronic components that creates 6 separate I2C buses? I think not, so it is just a straight connection.

Domino meinte
Maybe I'll have to consider using centralized ESCs again?

If you run into I2C problems, this is likely the source. In that case perhaps you can use some sort of shielded cable (coax-like cable) for the I2C cable to avoid the problem.

Domino meinte
The advantage of the ESCs out on the arm is the cooling effect from the rotors.

Yes that is very correct. It would be the best if there was a different signal bus than I2C to the BL-Motor-Ctrls, e.g. with CAN-bus. Perhaps this will come some time later.
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Does the I2C distribution board have any electronic components that creates 6 separate I2C buses? I think not, so it is just a straight connection.


Right, no seperate buses, one pad for all cables.

Foersom meinte
If you run into I2C problems, this is likely the source. In that case perhaps you can use some sort of shielded cable (coax-like cable) for the I2C cable to avoid the problem.


Thanks for the hint.
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Ich habe mal geschirmte Buskabel bestellt. Mal schauen, ob das ganze ev. wegen einem gestörten I2C-Singals ist? Denn manchmal habe ich beim starten der Motoren für ein paar Sekunden einen Error 17...
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Domino meinte
Ich habe mal geschirmte Buskabel bestellt. Mal schauen, ob das ganze ev. wegen einem gestörten I2C-Singals ist? Denn manchmal habe ich beim starten der Motoren für ein paar Sekunden einen Error 17...

I2C error during power on are not critical because you are not yet flying.

What battery are you using? If it is small or if it is old it might have developed some internal resistance and that means larger voltage swing when under heavy load e.g. at acceleration or at power on. If power is unstable because of heavy load that can also cause I2C errors.
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I2C error during power on are not critical because you are not yet flying.


Yeah but could it mean the i2c bus is weakened by the interference of the power cables, as you mentionend? Could it be that this weak signal is affecting the compass values that is also on the i2c bus?

Foersom meinte
What battery are you using? If it is small or if it is old it might have developed some internal resistance and that means larger voltage swing when under heavy load e.g. at acceleration or at power on. If power is unstable because of heavy load that can also cause I2C errors.


I am using brand new gens ace 6s 4500mAh and 9000mAh 25C. So the power shouldn't be unstable. Heavy load, well the copter ist 3700g or 4200g respectively including gimbal, camera and batteries.

The motors still have plenty of thrust (AHM 36-6 with 12x4.5 props).
« Bearbeitet von Domino am 13.04.2016 22:56. »
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Hallo Domino,

hast du bei deinen Bl-Ctrls auch alle Pufferelkos drauf gelötet?

Grüße Stephan
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Yeah but could it mean the i2c bus is weakened by the interference of the power cables, as you mentionend? Could it be that this weak signal is affecting the compass values that is also on the i2c bus?

Those are two different I2C busses, the BL-Motor-Ctrl I2C is from FlightCtrl, the compass I2C is from NaviCtrl. The I2C errors in GPX log is only from FlightCtrl as far as I know.

I recommend that you check older logs to look for cases of I2C errors during flight.

Domino meinte
I am using brand new gens ace 6s 4500mAh and 9000mAh 25C. So the power shouldn't be unstable. Heavy load, well the copter ist 3700g or 4200g respectively including gimbal, camera and batteries.

That sounds fine. I presume that 6S 4.5 Ah is used as a pair not as solo.
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Stephan Lukas meinte
hast du bei deinen Bl-Ctrls auch alle Pufferelkos drauf gelötet?


Es gibt bei den Afro-ESCs soweit ich weiss nur ein Slot?

Foersom meinte
I presume that 6S 4.5 Ah is used as a pair not as solo.


I use them solo. Gives me a flight time of around 8 minutes. I think in pairs they would be a bit too heavy. I got the 4500 not to exceed the limit of 100Wh to be able to take them on a plane.
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I use them solo. Gives me a flight time of around 8 minutes. I think in pairs they would be a bit too heavy. I got the 4500 not to exceed the limit of 100Wh to be able to take them on a plane.

They are small batteries. I think they have significant temporary voltage swings when you accelerate / climb with camera loaded. These are the moments where you put the heaviest load on the batteries and hence the most likely case the batteries could be the cause of I2C errors. Continue to use them, but if you encounter I2C errors, remember which battery was used and check the GPX log what you did just before error happened.

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MikroKopter - Forum » Navi-Ctrl & MK GPS » Position halten stabilisieren