Default PIDs seem VERY high!?

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Default PIDs seem VERY high!?

Postby axelnied » Mon Mar 16, 2015 2:00 am

I am building a M4 x-quad on a 240mm frame.
When I start the motors with "default" PIDs the motors (2204, 1960 kV) sound like there is sand in the bearings! :shock:
I had to reduce the Tilt Rate D from 34600 to about 5000, Tilt Angle D from 8400 to about 4000, and Tilt Angle P from 290 to 140 to have to motors "sound" more healthy. There is a lot more tuning to be done, but before I continue I wanted a sanity check that the DEFAULT PIDs are usable or not...

Is there anyone building something somewhat similar who is willing to share their PIDs?
I am using the latest M4 FW, with external ESCs, non-quatos (KISS ESCs).

I posted a screenshot after resetting to default:
DefaultPISs_M4.png
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Re: Default PIDs seem VERY high!?

Postby LPR » Mon Mar 16, 2015 4:59 am

Last fall I tried to get a quad flying with the AQ6 board with DIMU and I had the same problem as you. When I bought ESC32 and used Quatos the quad flew very well.

Since then I've read that the F term setting can smooth out motors when you lowering it. You can read about how it works here.

http://autoquad.org/wiki/wiki/configuri ... de-tuning/

Larry
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Re: Default PIDs seem VERY high!?

Postby Max » Mon Mar 16, 2015 6:49 am

A lot depends on your frame and how stiff it is. Maybe post a pic? Angel has done a lot of experimenting in this area (vibrations and PID tuning).

-Max
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Re: Default PIDs seem VERY high!?

Postby Altix » Mon Mar 16, 2015 9:43 am

Hi Axel,

actually, I’m working on a similar project. Its one of these popular 250 sized Mini H quads, which are not perfecty square. Electronics are the M4, a Get em expansion board, 18A KISS, MN1806 clones, 6*4,5 HQ props and a 3S 1.800 mAh Nanotech LiPo. I have another Mini H with the same electronics, but a Naze32 with baseflight instead the M4, and additionally, I have a Mini Hexa with the same motors, ESCs and props, but a NanoWii as FC. The latter two ones are flying very well and flying with speed is a lot of fun. That means, the motor, ESC and prop combo is nothing exotic and is proven to be a good combination of components.

My experience so far is, that the default PID are far too high for these little devils. I first came down to similar values as you did, and it were the same parameters as those you mentioned, that had the highest impact on the flying behaviour (Tilt Rate D, Tilt Angle D, and Tilt Angle P). The result was not exiting, but at least the quad was flying on an acceptable level. The problem I had at that stage was, that the motor values in the logfiles were still too high and the graphs showed „clipping“. That’s why I further reduced those three parameters roughly to one third, if I remember correctly (I’m sitting in the office right now with no access to my data). Now, the clipping almost disappeared and the quad is still flying fairly stable. But now, I have a new problem: the agility is very poor and the reaction on stick commands is so slow, that flying is no fun (flying with the values before was not much better and very poor compared to the performance of my Naze32 or NanoWii). I could solve the problem on yaw by increasing the deg/s parameter to around 180, but pitch and roll is still a mess.

I don’t want to hitchhike your thread here, and because I have similar problems with a much larger X8, I will open a new thread on that. But I can confirm, that the default PIDs are far too high for these type of small quads. May be, that Quatos will be the final solution, but for the timebeing I will continue on the PID thing, as it must be possible to get this devil flying just on PID tuning.
Regards, Michael
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Re: Default PIDs seem VERY high!?

Postby sandmen » Mon Mar 16, 2015 11:13 am

@Altix, which FC revision did you use?
Currently working on this topic, and if my test's are success full, it would be nice, if you test this changes.
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Re: Default PIDs seem VERY high!?

Postby Altix » Mon Mar 16, 2015 11:46 am

Hi Peter,

it is an actual M4v2, so it is not one of the early beta boards. If there is something I should test, please let me know. At least I will try to do my very best ;)
Regards, Michael
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Re: Default PIDs seem VERY high!?

Postby brat002 » Tue May 26, 2015 2:46 pm

I have these problems too. Already fried two motors for last 2 weeks of tunning PID parameters. Looks, like M4 is totally unflyable solution without quatos...
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Re: Default PIDs seem VERY high!?

Postby Max » Tue May 26, 2015 5:32 pm

Brat, If you're "frying motors" (whatever that actually means), you have bigger problems than PID settings. Your last statement is completely untrue -- the M4 and AQ6 (both have the same sensors and run the same code) fly just fine with PID controller, as proven by many people.

-Max
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Re: Default PIDs seem VERY high!?

Postby axelnied » Tue May 26, 2015 5:38 pm

Brat, I burnt two motors with M4 and PID myself. The Motots got REALLY really hot, just running them at 30 to 40% throttle.
I ditched the frame as it was way too soft and too many vibrations. Sorry I cannot quantify that... got a new frame with 3mm carbon arms. also new motors from RCMC. Bench tests look much better. motors run cool.
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Re: Default PIDs seem VERY high!?

Postby brat002 » Tue May 26, 2015 6:38 pm

What motors you used before?
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