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DIY Dome Problem with Az position

  • Posts: 16
  • Thank you received: 1
Hi,
i have built a DIY-Dome and have automated with a stepper the dome rotation.
I have create a new driver for this and now I have a problem with the az position of the dome.

The calculated az position is not the same as in the EQMod Mount driver.
Example when i drive to the east Position where it should have 90° it goes to 138°.

Attached the log file where the mount is slewing from parking position to east position and dome is following.

Hope someone can help me with the problem.

 

 

 

File Attachment:

File Name: log_17-30-...17-2.txt
File Size:185 KB
2 years 3 months ago #78662
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Hi Thomas and welcome to INDI forums. So why do you expect them to match? The slaving AZ does not necessary match the mount AZ due to all the math involved to ensure that the telescope is center in the dome slit.
2 years 3 months ago #78672

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Thanks for the feedback, I also understand that the position of the telescope does not have to be the same as the dome. I've tried a couple of positions but they don't fit together. The telescope is at 91 and the dome should be at 137. I also entered the coordinates in Ferran Casarramona's spreadsheet and according to the calculation, the same thing came out there.

 

Maybe you could give me a clue where I can start looking here.
Last edit: 2 years 3 months ago by Thomas Pichler.
2 years 3 months ago #78689
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Your slaving parameters look a bit odd, for example OTA offset should usually not be zero as it's the distance of OTA center line from the intersection of RA and DEC axis of the mount. Also shutter width looks a bit narrow. In any case calibrating those is vital for reliable slaving. There was a procedure documented on this forum somewhere (sorry couldn't find it with quick search even though I wrote it myself...), but the idea is to isolate each setting and tuning them one by one.
The following user(s) said Thank You: Thomas Pichler
2 years 3 months ago #78692

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Thank you Jarno, the OTA offset was the problem.

And i found the instruction for it.

Dome Instruction
The following user(s) said Thank You: Jarno Paananen
2 years 3 months ago #78699

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I have tested it now with the dome and mount in reallity and tried the calibration procedure for the slaving paramters for the dome.
When i only move the DEC axis of the mount it is working correct, but when i bring the DEC back to 90° and then move only the RA axis it is not moving correct.
When i slew the RA axis to the east side the dome first moves to the east side then it slew to the mirrored side (log file). This happens every time.

When North = 0°, West= 90° and East 270° --> DEC is working
When North = 0°, West= 270° and East 90° --> AR is working

Where can this come from?

When someone need more informations do not hesitate to contact me.

Thanks for your replies.

 
 

File Attachment:

File Name: log_09-49-02_.txt
File Size:7 KB

 
2 years 3 months ago #78701
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OTA offset should probably be positive, negative might make the pier side calculation go haywire.
2 years 3 months ago #78706

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Hi Thomas.
are you building a DIY-Dome with stepper motors? Wow! Good work.
Are you planning to publish your work? I'd like to build it. I have been planning to build a dome for several years and are still looking for DIY control with INDI. Nothing commercial, just DIY.

Tomas
2 years 3 months ago #78745

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So now i had time to check everything and now it is running. Maybe some tuning in the position but scope now always in center position.
Problem was something in the rasperry, i did a complete reset and then it was working.

@Jarno Pannanen: Thx for your support
@Tomas Kalisch: When i have finished it completely i will post it, but for this i have to do some comments in the code ;-D
2 years 3 months ago #78862

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