Xact Servo Settings

[spoke2570]

I have a fair number of Xact servos at this point, and love the data I can get back out of them. Most of the servos I have developed some jitters in use, in a few cases it was a divergent function. I modified the PID settings to address this with good success. I have found some decent information on RCGroups, but nothing for the tiny 5600 series that I am goofing off with.
The ask:
Please add a fact page to your site that defines these settings (and others) in ETHOS and the Xact servo tool and has some tested ones for the servos that you carry.
Best
Peter B

 

[Wayne]

Peter - Will do our best, these have so many settings it is insane. Would love a more simplistic offering. Maybe an basic/expert mode.

 

[spoke2570]

LOL From FrSky? Like a works vs doesn't work mode? Seriously these things are pretty sweet, it just seems that no one really ever field tested them before deployment.

..ahem Airbossrc.com has one for the Xacts that they carry....

 

[gnichola]

I was over on RCGroups and there was a thread that started with servo buzz that then turned into a settings thread with various folks giving their numbers and such. I asked a question that has not yet been answered, about the point of all the settings. Like, why do you need to change settings? Are some uses benefited by one set of settings?

 

[Wayne]

Yes, the settings are so detailed that settings that work for one application may not work for the next. FrSky does tune each family of servos with "safe" tuning that should work out of the box for most applications. We occasionally see feedback loops on very fancy models as they tend to have more substantial linkages that can present this sort of "tight" play that will create the feedback loop. Adjusting the programming for the servo can and will solve the issue, but it is a matter of what to adjust that gets tricky.

 

[spoke2570]

My fancy model in point is a one pound Fancy Foam FSST. It exhibited a self exciting situation.

 

[spoke2570]

Might be interesting to test on a pull-spring system...

 

[Wayne]

If you disconnect the elevon, does it stop the shakes?

 

[spoke2570]

Definitely some mass in the system is required to create the situation. The servos definitely did not do this while mechanically matching them on the bench, prior to installation. Friction seemed to reduce/eliminate the problem, as well. The surfaces move super freely so... Moving the sticks deliberately (no shocks) avoided the issue. Somewhere the settings that worked are written, but that box has not yet been opened (I'm moving). I think there may be something with the rapid acceleration of the arm and the duration between positional reports; add a little mass and it is forever overshooting.

Anyway I will be playing with these things some as FBus looks like a lot of fun filled data, with less wire and less weight.

 

[Wayne]

I was given a table by one of the other FrSky service dealers, but they warned that even with in a servo family the numbers may need to be adjusted. So a bit of a game still..

 

[spoke2570]

That is a phenomenal start. I know that some bullet proof settings for these must exist as KST, MKS, even the ultra failing DualSky have very nice, working PIDs loaded in their digital servos.

 

[spoke2570]

Maybe see if you could get the definitions list approved from those guys I mentioned above. It denotes a P1/P2 ratio and 3 integer constants to feed their differential equation. If FrSky is unwilling to offer it up to be optimized, then at lest we can try to put together enough information to determine a general form for their control model's equation. (..sorry. I know it is work but I like spending money with y'all, prefer it to other FrSky vendors.)

These servos are super cool. soft start, ultra smooth running. QUIET! Data Source for servo power bus (if separate from Rx power). plus CURRENT!! (What of my 10 control surfaces was binding last flight, and needs attention..?) If they could be plugged in and expected to work as well (no hassle, just works) as other premium brands (MKS, KST, HiTec, BlueBird, blah, blah). Virtually no FrSky Tx owners would buy any other brand at that point, and some competing Tx brand users would buy them, too.

Preaching to the choir..
..also ..SloperSteveTribute.. He's retired and goofing off these days, right?