Tuning soft frame

Info and discussion about the autonomous Micro FC, suitable for nanos, micros and mini multirotors

Re: Tuning soft frame

Postby LPR » Wed Feb 24, 2016 8:19 pm

Pat

If you attach a complete parameter file I can send a complete one so all you'll need to do is load the file.

The kind of control you are getting is uncommon so I should have a look at the complete file.

Larry
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Re: Tuning soft frame

Postby Patnet » Wed Feb 24, 2016 8:22 pm

Thanks Larry, attached.

revised_params_112515.txt
(14.83 KiB) Downloaded 193 times
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Re: Tuning soft frame

Postby Max » Wed Feb 24, 2016 9:35 pm

LPR wrote:If you attach a complete parameter file I can send a complete one so all you'll need to do is load the file.

Loading some parameters from a partial file is just fine, and is always my preferred method since it is much easier to see what has changed. Most of the params in this case don't need to be touched, only a few PIDs. Why take the chance of messing up something else?

Pat, yes, you should post a log or at least part of one showing a hover in clear air (not ground effect). A quick video may also help, many people can tell from the sound what needs to be adjusted. My guess is that the majority of the vibrations are being cause by the props or other factors besides the arms, and ultimately that's what you need to get rid of. But that's a pretty generic guess.

For tuning PIDs there is simply nothing easier than putting them on Tx knobs and adjusting in flight. I would not willingly go back to doing it the old way. Highly recommended.


-Max
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Re: Tuning soft frame

Postby Max » Wed Feb 24, 2016 9:43 pm

Pat, is this right?

Code: Select all
IMU_FLIP                           1
IMU_ROT                        -135


-135? But a regular Quad-X mix?

Also did you tare/calibrate this board/MR recently?

-Max
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Re: Tuning soft frame

Postby Patnet » Thu Feb 25, 2016 12:25 am

Max wrote:Pat, is this right?

Code: Select all
IMU_FLIP                           1
IMU_ROT                        -135


-135? But a regular Quad-X mix?

Also did you tare/calibrate this board/MR recently?

-Max


Got to be -135. No? No magnometer calibration recently. Same place on earth. I have done Accelerometer/Gyros frequently.

2016-02-24 14.55.56.jpg
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Re: Tuning soft frame

Postby Max » Thu Feb 25, 2016 1:06 am

I dunno, can't tell which way is forward in the closeup... :) -135 would be yellow LED forward, and flip = 1 would be GPS chip up. So if forward in your picture is to the right, then yes, I think that looks correct. Can't tell you how many times I've messed up the rotation/flip/motor order, so I always recheck that whenever something doesn't seem right.

-Max
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Re: Tuning soft frame

Postby Patnet » Thu Feb 25, 2016 1:28 am

Max wrote:I dunno, can't tell which way is forward in the closeup... :) -135 would be yellow LED forward, and flip = 1 would be GPS chip up. So if forward in your picture is to the right, then yes, I think that looks correct. Can't tell you how many times I've messed up the rotation/flip/motor order, so I always recheck that whenever something doesn't seem right.

-Max


Yes, of course, how ridiculous of me. You wouldn't know forward. But yes, yellow light forward, Microprocessor under, GPS on top.

I don't have any hover logs for the aluminum arms, just flight. I'm waiting for more arms from China. Could be a while.

I have recent flight logs for the current plastic setup and can get you hover for that setup when the wind dies down a bit here. Maybe tomorrow.
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Re: Tuning soft frame

Postby Patnet » Thu Feb 25, 2016 10:08 pm

Max wrote:yes, you should post a log or at least part of one showing a hover in clear air (not ground effect). A quick video may also help, many people can tell from the sound what needs to be adjusted. My guess is that the majority of the vibrations are being cause by the props or other factors besides the arms, and ultimately that's what you need to get rid of. But that's a pretty generic guess.
-Max


Thanks Max, here are the Motors and the IMU logs. It's not all that much of a hover, because I can't keep it in one location--drifts. The props are balanced, motors do clip, vibrations look OK to me, and I'm also attaching the ecalc, showing it in range.

022516_-AQL_IMU.jpg
022516_-AQL_IMU.jpg (57.98 KiB) Viewed 5474 times


022516_-AQL_Motors.jpg
022516_-AQL_Motors.jpg (48.37 KiB) Viewed 5474 times


022516_ecalc.jpg
022516_ecalc.jpg (52 KiB) Viewed 5474 times
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Re: Tuning soft frame

Postby Max » Thu Feb 25, 2016 10:37 pm

Hi Pat,

So, what has happened since this post: viewtopic.php?f=40&t=4687&start=20#p35251 ? You had no motor clipping there (though their range is still pretty wide).

I'm not sure, but from what you posted it looks like "classic" vibration issue where the PID controller is basically amplifying the gyro output. I would try to tune the attitude PIDs to where you get the best control response but with as narrow motor output range as possible, as far from clipping as you can get. Until then, it'll be a "nervous" flyer at best. Reducing Tilt Angle D is the quickest approach, but it will reduce control authority and as you've found, if you reduce it too much you'll loose all control entirely. After you find a happy medium there, the other rates (esp. Tilt Angle D) can sometimes be increased to give you back some control response.

I could also build you a special firmware which reduces the sampling rate of the Gyro sensor... a few people have had good luck with it on difficult frames (including myself). Theoretically the same result can be achieved by tuning the attitude PIDs, and I'd recommend that approach vs. a custom firmware. Putting the PIDs on Tx knobs (with my beta firmware) would be the first thing I'd try since it makes PID tuning almost fun :)

HTH,
-Max
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Re: Tuning soft frame

Postby Patnet » Thu Feb 25, 2016 10:52 pm

Max wrote:Hi Pat,

So, what has happened since this post: viewtopic.php?f=40&t=4687&start=20#p35251 ? You had no motor clipping there (though their range is still pretty wide). -Max


I migrated from a 3S 3.3 Amp to 4S 10 Amp battery. Added over 500 grams. Plus new batch of chaeper, same kv motors--don't ask why. Long story.

It looks to me like only one motor is clipping (Motor 6). Could that be a bad ESC or motor? Which one is Motor 6 in the geometry? That's the red one in the graph. I don't think the issue is the motors though, I'm getting the same lack of control with the 530kv set.

I'm just using a 6 channel transmitter, so don't have the luxury of adding PIDs, although it does sound like a good idea. I have PID controls through BT and the app, though, so can work on the fly. Thanks for offering to build the firmware. let me work on more PIDs first. I agree that's probably a better way to go. Larry kindly said he'd come up with some PID ideas too.
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