Use of UltraESC with AQ

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Use of UltraESC with AQ

Postby phynix » Tue Jun 03, 2014 10:30 am

Hello,

As I have two AQ-Boards now (one with DIMU, one with AIMU) that randomly freeze in mid flight (viewtopic.php?f=31&t=3086), I probably have to take the possibility of an influence of my setup into account.

The frame is a simple CFK-F8 equipped with 2212-Motors combined with the UltraESC. I had no issues so far using 3S batteries. But when I switch to 4S, I have random freezes. The AQ simply stops responding, no reboot and the status-LEDs simply keep there state. Often all motors simply stop at the same time and the copter comes down like a stone. It only happens with the motors running!

My question: Does anybody use the UltraESC with the AQ, mybe also with 4S? Is it possible that they create something in the PWM-lines that causes the AQ to crash?!?

Soeren
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Re: Use of UltraESC with AQ

Postby JussiH » Tue Jun 03, 2014 12:16 pm

I´d really like to see a log of this phenomenon. Pls also post firmware version.

As for UltraESC, I will ask Felix to offer an opinion.
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Re: Use of UltraESC with AQ

Postby phynix » Tue Jun 03, 2014 2:40 pm

Hi Jussi, I did observe this behaviour with the firmeware that has the native hott extension and is based on r374 (with DIMU). I flew it for >20 batteries without problems on 3S. Then I switched to 4S and it happened 4 times on one batterie. I thought maybe a newer firmeware solves this issue, and switched to r397+native hott. But again it freezed at the very first battery. The only thing I adjusted was the factor throttle...

As mentioned, It looks exactly the same compared to what I observed earlier with a differen AQ-Board (that one was using AIMU and the "stable"-firmeware) on the same frame. The logs just ends in mid-air. It behaves perfectly, and suddently just plunges to the ground with all motors off. I do have a log with r374+hott, I can upload it tonight. if it might help, I can also try to do a video as soon as my camera is back from repair.

Concerning the UltraESC: When I started using them, I suddently got I2C errors on the AlexMos-Gimbal that I never had before with SimonK. So maybe they are a little bit more "dirty" ... and when using higher voltage, something exceeds a certain tolerance-level of the AQ - just a crazy idea. This is realy causing me a headache right now - especially as no one else has this problem, but I do with two different boards !!!
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Re: Use of UltraESC with AQ

Postby LPR » Tue Jun 03, 2014 3:24 pm

Soeren

I have used Ultra ESC and the new AQ DIMU board with 3s, 4s and 5s lipos without the problem you're seeing.
You may be right that some signal from the Ultras could be causing your problems. Because you can reproduce the motor stops you should be able to find a solution. A resister on the ESC signal line could make a difference. You could try twisting the Ultra ESC's control wires also.

Larry
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Re: Use of UltraESC with AQ

Postby phynix » Tue Jun 03, 2014 3:58 pm

Thank you Larry, that it works for you is a good information for me. I will try to get an oscilloscope to check the signal lines.
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Re: Use of UltraESC with AQ

Postby JussiH » Tue Jun 03, 2014 4:03 pm

You could have been suffering from a recently discovered PWM bug that was fixed in R396.

The basic problem was that an additional 125 us was added to the PWM output, so after upgrade you might need to retune throttle factor. Its not unlikely that this extra 125 uS could have caused adverse ESC behavior in some setups.

But since you have this with R397, and the problem seems tied to high voltages its probably not FW failure.

If the log ends mid-air it sounds like a reset or power failure. Its theoretically possible that a spike on a PWM line could cause a reset of the MCU. Does the board boot up again?

If you can reproduce it in a safe manor (tied down) and document it (video, logs), it would be very helpful.

To then work out if its a noise problem, you would need to hook up a scope and look for spikes at the time of the shutdown/reset. I would be very interested if a connection could be made between the reset and some noise event.

I am not completely up to date on UltraESC, but I think there was some reports about it causing ripple in the supply at high voltages. Felix will have to jump in and elaborate there.

As Larry Points out (thanks), you should twist the signal and supply wires and try to add a 100R resistor to the signal lines.

If the problem is ripple in the supply, a possible solution is to add a ferrite core to the AQ supply wire.
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Re: Use of UltraESC with AQ

Postby phynix » Tue Jun 03, 2014 4:27 pm

Thanks for all your support! I will try to answer what I know:
- with r397 I had it only one time, then I stopped flying.
- the AQ is not booting again. A manual reset is needed.
- I had it with the AIMU board reproducible but randomly with the copter strapped down. There it also happened only with 4S and with Motors running. I did not test it with the DIMU board strapped down yet. Logs, reports and so on in the link in my first post. @Jussi: I think you had already a look at one of the logs. I was told to reinstall the firmeware, then it seemed to be fine (I only testet it strapped down, not flying). But now it seems to be back again on another board.
-Back then with the AIMU strapped down, I checked the supply voltage the the AQ, it was clean. I also probed one signal wire to one of the esc: clean PWM signal; 3.3V amplitude. But I did noch check all off them.

Another question:
What is the best way to connect the esc: with signal and ground connected (creating a ground loop ...) or only signal connected (probably risking an offset in Voltage in the signal wire)?
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Re: Use of UltraESC with AQ

Postby JussiH » Wed Jun 04, 2014 11:42 am

Always have the signal ground connected, relying on main battery ground for PWM signal reference is bad practice because of the ground potential difference it creates. If you left out ground wires, that could be a very likely explanation.

Twist the ground wire around the signal wire to increase its noise rejection and inductive potential.
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Re: Use of UltraESC with AQ

Postby phynix » Wed Jun 04, 2014 7:10 pm

Ok, I checked all the PWM-lines with an scope against the GND on the AQ board: clean, only a small additional oscilating pulse (with an amplitude of about 0.1V, length < 1us) on top of the main signal visible. I checked all 8 connections - two of them do not have the GND connected (for testing). But they all look the same on the scope, no spikes. The ones with GND connected are twisted, of course. All signal cabels are routed in a way that a CFK-plate is in between them and the the (twisted) power-lines.

Maybe there is some random spiking somewhere happening, but that would be extremely hard to catch. While I was measuring, it has freezed for about four times, and I did not see anything on the PWM line that was connected to the scope ad that time. Interesting: the PWM stays on, with minimum width, but the esc stays armed.

Power in to the AQ is stable, too.

Signal from the receiver has no spikes, two.

So I am realy running out of ideas :?:

Edit: one more thing I noticed: When not connected to the AQ, the PWM input of the esc has a residual potential of 5V... probably no problem, just wanted to note it.
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Postby phynix » Sun Jun 22, 2014 6:45 pm

Update: The AQ that has the problems mentioned above does fly without problems on a quad with simple simonK-esc on 4S batteries. Telemetry and receiver were exactly the same.

So there is probably some bad interaction between ultraESC and AQ on the Octo. All signal wires are twisted with the corresponding GND. This is a worry to me as the AQ seems to be dangerously sensitive on its inputs, right? As I probed all the PWM-outs of the AQ and also the supply voltage without any noticeable, I am realy running out of ideas. What else could be the reason? If this is not working out somehow, I have to think about switching to another flight controll... even so I like the performance of the AQ very much.

I did not yet manage to test the resistors in the PWM lines. I got some with 180Ohm, but did not yet find the time to solder them in.

Sören
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