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INDI Library v1.8.5 Released (19 Apr 2020)

April 2020 release of INDI Library v1.8.5 introduces new drivers while providing fixes and improvements to existing devices and core framework.

Internal autoguide in EKOS makes thins worse

3 months 3 weeks ago
raul
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Internal autoguide in EKOS makes thins worse #49487
I tried for the first time to use autoguide feature of EKOS. I'm using the autoguider only for RA (also for calibration).
A strange thing happens. Calibration phase works as intended, meaning that I can see movement on RA axes (on the guiding camera image) and I can hear the mount motor working. But when autoguiding phase starts does the opposite thing that is supposed. Instead of correcting the (periodic) errors of tracking, it amplifies them. Over the time the "corrections" in RA movement become bigger and bigger. My assumption is that the corrections are going in the wrong direction. Instead of correcting the RA axis, they are making axis to go in the opposite direction. But I may be wrong.

Can anybody explain that ?

My setup is:
- OnStep controlled mount
- guiding camera: converted Logitech C270 webcam (driver indi_v4l2_ccd)
- guiding via OnStep driver (directly)

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3 months 2 weeks ago
knro
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Internal autoguide in EKOS makes thins worse #49564
Turn on guide logging and attach the log from it.

Jasem Mutlaq
Support INDI & Ekos; Get StellarMate Astrophotography Gadget.
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3 months 1 week ago
raul
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Internal autoguide in EKOS makes thins worse #49959
First evening with clear sky. Here is the log file.

File Attachment:

File Name: log_18-16-...2-22.txt
File Size:64 KB
Attachments:

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3 months 1 week ago 3 months 1 week ago by schwim.
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Internal autoguide in EKOS makes thins worse #49961
Do you have the guiding log guide_log.txt? On linux it should be located in ~/.local/share/kstars.

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3 months 1 week ago
raul
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Internal autoguide in EKOS makes thins worse #50061
Found it.

File Attachment:

File Name: guide_log.txt
File Size:1 KB
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3 months 1 week ago
Herrhausen
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Internal autoguide in EKOS makes thins worse #50064
It is important to set control parameters correctly, "proportional gain" in particular. Did you take care of it?
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3 months 1 week ago
El Corazon
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Internal autoguide in EKOS makes thins worse #50066
And those control parameters vary wildly from mount to mount as I found out with my iOptron SmartEQPro+. There, guide rate has to be set to 1 (not 0.5), and proportional gain in RA to 200, but on DEC to only 67. With that I finally get the mount to stay on target.
Also, try the ALWAYS RECALIBRATE AFTER MOUNT SLEW setting in the guide calibration module. That can make an enormous difference.

Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
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3 months 1 week ago
schwim
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Internal autoguide in EKOS makes thins worse #50067
If I graph your RA Error it looks like over correction is happening. Note the end of it:



This is the correction being sent to the mount. Note that it flatlines toward the end. This is probably due to a max move limit.



You probably won't recover from that. Try adjusting the proportional gain for your mount as was suggested.

You can also try to see what the mount is doing unguided by starting guiding with the corrections disabled. This will tell you the "natural" guiding needs of the mount and could help with further tweeks.
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3 months 1 week ago
raul
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Internal autoguide in EKOS makes thins worse #50209
I played around with "Control Parameters"/"Proportional Gain" and, indeed, it makes auto-guiding work as intended. It isn't yet perfect, but there are other factors at play (my guiding hardware is DIY and needs improvement). Anyway, on a longer exposure I can already see the difference.

Many thanks to all of you, guys, for your help !

By the way, never heard about proportional gain before. Is there any documentation that explains what it does ?

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3 months 1 week ago 3 months 1 week ago by Bart. Reason: forgot controller in control loop.
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Internal autoguide in EKOS makes thins worse #50211
The autoguider control loop consists of a measurement (the image from the guide scope) and an actuator (the mount that responds to guide pulses) and the controller (Kstars). The autoguider measures the position of a guide star, knows where it should be and based on the difference between the two (the error), sends a signal to the mount to correct this. How large this signal will be, is dependent on a few gain settings.

Proportional, Integral and Derivative (PID) are the gain factors that are used in the commonly used PID control loop.
See:
en.m.wikipedia.org/wiki/PID_controller

The stability of the control loop is strongly dependent on these gain settings. It's easy to get it wrong. The settings are a bit of a trade-off between stability, fast settling time and remaining error.

15 cm wavefront condensor | Earth rotation undo-er | Few photon discriminator plates | Photons to electrons transmogrifier | Stellarmate

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3 months 1 week ago
Bart
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Internal autoguide in EKOS makes thins worse #50212
...Which makes me think now:
Would it be interesting if there is a PID self-learning button? I wouldn't mind spending some time developing/ implementing a autotuning alghorithm if there is interest (Jasem?).

15 cm wavefront condensor | Earth rotation undo-er | Few photon discriminator plates | Photons to electrons transmogrifier | Stellarmate

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3 months 1 week ago
El Corazon
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Internal autoguide in EKOS makes thins worse #50215
That would cool! I could definitely use that.

Jo

Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set

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