Mach2 with CP five jiggling while tracking


Allen Ruckle
 

Last night while setting up my telescope for Astro photography I noticed, while trying to calibrate PhD 2,  I noticed the stars were short dashes in the east west axis. I had started the telescope up using the V2 ASCOM driver and I had started PhD, as I started PhD2 looping I noticed all the stars in the frame were dashes which I then tried to calibrate to see if that would alleviate the problem, however it would calibrate on the dashes as if they were stars.
      I then checked the image  from the main camera, the stars seem to be jumping back-and-forth. I then connected the hand controller to see if that would calm anything down, no luck, so all I could do to proceed by turning off the APV 2 ASCOM driver and PhD 2 and run the telescope unguided, under only the control of the hand pad.

it was as if the tracking was the result of two systems fighting for control.

has anyone seen this issue before with the Mach2 p, and corrected the problem.

thank you for any help you can provide
aruckle


Jeffc
 

I have the same issue.   

I found if I slightly imbalance the RA (move counterweights down) the problem is mitigated.   Also fwiw I’m using a 12” SCT which I think is just at the limit of the Mach2. 

However, I discovered this back in late September and have only had the mount out for a short session in October.  

During the October session I was trying to image the moon.  I did a goto to the moon, then noticed on the live video the moon flopping back and forth.   I had the patio lights on and could see the RA oscillating a few degrees.   I tried to capture this on a smartphone video but it’s not noticeable. 

I’ll upload a video of the moon flopping when I find it.  

(I had some conversation with Roland on this but I haven’t followed up on my part as I wanted to gather more info.)

-jeff


On Nov 7, 2021, at 9:44 AM, Allen Ruckle <aruckle@...> wrote:



Last night while setting up my telescope for Astro photography I noticed, while trying to calibrate PhD 2,  I noticed the stars were short dashes in the east west axis. I had started the telescope up using the V2 ASCOM driver and I had started PhD, as I started PhD2 looping I noticed all the stars in the frame were dashes which I then tried to calibrate to see if that would alleviate the problem, however it would calibrate on the dashes as if they were stars.
      I then checked the image  from the main camera, the stars seem to be jumping back-and-forth. I then connected the hand controller to see if that would calm anything down, no luck, so all I could do to proceed by turning off the APV 2 ASCOM driver and PhD 2 and run the telescope unguided, under only the control of the hand pad.

it was as if the tracking was the result of two systems fighting for control.

has anyone seen this issue before with the Mach2 p, and corrected the problem.

thank you for any help you can provide
aruckle


Jeffc
 



Here’s the video of the oscillation in RA.  It’s kinda short.  I’d like to acquire more data/info for troubleshooting.  


Btw… this Mach2 is unguided.   In this case it is almost like the goto for the moon overshoots a bit.. then corrects and the correction overshoots, and it continues. 

Back in September I had a similar problem when doing the gotos while building the model.   The image would have short lines for the stars.  Not all points in the model had this problem , but I didn’t see any pattern such as close the horizon , specific part of the sky, etc. 

I’m not using any auto guiding with the Mach2.  (Been thinking about it for longer exposures tho.)

At the time, I was using the latest APPC etc. (I don’t have the version handy — it’s on the other computer, but can get it if needed.)

-jeff 

On Nov 7, 2021, at 11:27 AM, Jeffc via groups.io <jeffcrilly@...> wrote:

I have the same issue.   

I found if I slightly imbalance the RA (move counterweights down) the problem is mitigated.   Also fwiw I’m using a 12” SCT which I think is just at the limit of the Mach2. 

However, I discovered this back in late September and have only had the mount out for a short session in October.  

During the October session I was trying to image the moon.  I did a goto to the moon, then noticed on the live video the moon flopping back and forth.   I had the patio lights on and could see the RA oscillating a few degrees.   I tried to capture this on a smartphone video but it’s not noticeable. 

I’ll upload a video of the moon flopping when I find it.  

(I had some conversation with Roland on this but I haven’t followed up on my part as I wanted to gather more info.)

-jeff


On Nov 7, 2021, at 9:44 AM, Allen Ruckle <aruckle@...> wrote:



Last night while setting up my telescope for Astro photography I noticed, while trying to calibrate PhD 2,  I noticed the stars were short dashes in the east west axis. I had started the telescope up using the V2 ASCOM driver and I had started PhD, as I started PhD2 looping I noticed all the stars in the frame were dashes which I then tried to calibrate to see if that would alleviate the problem, however it would calibrate on the dashes as if they were stars.
      I then checked the image  from the main camera, the stars seem to be jumping back-and-forth. I then connected the hand controller to see if that would calm anything down, no luck, so all I could do to proceed by turning off the APV 2 ASCOM driver and PhD 2 and run the telescope unguided, under only the control of the hand pad.

it was as if the tracking was the result of two systems fighting for control.

has anyone seen this issue before with the Mach2 p, and corrected the problem.

thank you for any help you can provide
aruckle


Brent Boshart
 

I had/have the same issue with my Mach2.  Roland sent me some APCC commands to help dampen the encoders.  It affected both axes for me.  I thought it was totally solved but have since seen some remaining "judder" after a fast slew - I need to make further adjustments with commands. It takes up to 30 seconds to settle.  This is with a C8 mounted so no where near the limit of the Mach2. Before the APCC commands,  it took a while to even settle after a dither while tracking.  


Allen Ruckle
 

I have attached a image taken of the Veil nebula taken while the mount was jiggling in the RA axis. The length of exposure was 75 seconds and, the focal length of the telescope is 674 mm.
therefore the amount of jiggle  (length of star streak) is 2min 45sec of arc.  The telescope was visually oscillating at a frequency of about 60hz.

The only change, I think, has changed from the previous use of the imaging system may be an update of the PHD-2,6dev2 app. 

My next step is to revert the PHD-2 app to the previous version.




Roland Christen
 

I will send you some instructions to eliminate the oscillations.
By the way, has nothing to do with PHS2 or any other outside programs attached to the mount.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Allen Ruckle <aruckle@...>
To: main@ap-gto.groups.io
Sent: Mon, Nov 8, 2021 3:25 pm
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

I have attached a image taken of the Veil nebula taken while the mount was jiggling in the RA axis. The length of exposure was 75 seconds and, the focal length of the telescope is 674 mm.
therefore the amount of jiggle  (length of star streak) is 2min 45sec of arc.  The telescope was visually oscillating at a frequency of about 60hz.

The only change, I think, has changed from the previous use of the imaging system may be an update of the PHD-2,6dev2 app. 

My next step is to revert the PHD-2 app to the previous version.




--
Roland Christen
Astro-Physics


Allen Ruckle
 

Thank you Roland for your response to my post.


Roland Christen
 

Were you able to use APCC for the info?

Roland

-----Original Message-----
From: Allen Ruckle <aruckle@...>
To: main@ap-gto.groups.io
Sent: Mon, Nov 8, 2021 8:59 pm
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

Thank you Roland for your response to my post.

--
Roland Christen
Astro-Physics


Jeffc
 

Roland - Earlier (about a month ago) I replied with some output from mount commands you asked for.   I’m guessing that thread may have been lost in the noise or spam.  

In any event here’s the data I extracted for those terminal commands… let me know if you need additional info.   

Thx

Here's the output of the terminal commands:

$RS#  =  10#
$RA#  =  40#
$RN#  =  8#
$RZ#  =  0#

Also copied as a screenshot attached.


-jeff

image.png


Roland Christen
 

Please send me any information about your mount to chris1011@.... That way it won't get lost on this user group. Also include George@...

Roland Christen
Astro-Physics Inc.

-----Original Message-----
From: Jeffc <jeffcrilly@...>
To: main@ap-gto.groups.io
Sent: Mon, Nov 8, 2021 10:46 pm
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

Roland - Earlier (about a month ago) I replied with some output from mount commands you asked for.   I’m guessing that thread may have been lost in the noise or spam.  

In any event here’s the data I extracted for those terminal commands… let me know if you need additional info.   

Thx

Here's the output of the terminal commands:

$RS#  =  10#
$RA#  =  40#
$RN#  =  8#
$RZ#  =  0#

Also copied as a screenshot attached.


-jeff

image.png

--
Roland Christen
Astro-Physics


Clayton Yendrey
 

Roland,

I don't have an AP mount (on the waiting list for a Mach2), but this sounds very similar to the SDE generated oscillation that has plagued Ioptron's attempt at encoder equipped mounts.  The threads on their issue with this on CN are so numerous that it really deserves its own group... ;-)

Is that any relation to what is occurring here?

"Sub-divisional error is cyclic, occurring with each interval of the scale or scanning pitch (i.e with each signal period), but it does not accumulate and is independent of the scale or travel length. The two primary causes of SDE are mechanical inaccuracies and misalignment between the scale and the read head, although harmonic disturbances can also cause distortions in the sine and cosine signal"


Roland Christen
 

No, it is not SDE that is causing this. The Mach2 and our other encoder mounts do not have SDE. It is caused by a high inertial load on the mount (large heavy scopes with lots of counterweights) that needs a higher damping factor in the control loop. Simple adjustment in software really.

Roland

-----Original Message-----
From: Clayton Yendrey <cyendrey@...>
To: main@ap-gto.groups.io
Sent: Wed, Nov 10, 2021 8:46 am
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

Roland,
I don't have an AP mount (on the waiting list for a Mach2), but this sounds very similar to the SDE generated oscillation that has plagued Ioptron's attempt at encoder equipped mounts.  The threads on their issue with this on CN are so numerous that it really deserves its own group... ;-)
Is that any relation to what is occurring here?
"Sub-divisional error is cyclic, occurring with each interval of the scale or scanning pitch (i.e with each signal period), but it does not accumulate and is independent of the scale or travel length. The two primary causes of SDE are mechanical inaccuracies and misalignment between the scale and the read head, although harmonic disturbances can also cause distortions in the sine and cosine signal"

--
Roland Christen
Astro-Physics


 

>>>It is caused by a high inertial load on the mount (large heavy scopes with lots of counterweights) that needs a higher damping factor in the control loop. Simple adjustment in software really.

I can vouch for that - Roland helped us with these settings on our CDK20 which is nearly 200lb on our AP1600. A few software tweaks improved performance considerably



On Wed, Nov 10, 2021 at 8:38 AM Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
No, it is not SDE that is causing this. The Mach2 and our other encoder mounts do not have SDE. It is caused by a high inertial load on the mount (large heavy scopes with lots of counterweights) that needs a higher damping factor in the control loop. Simple adjustment in software really.

Roland

-----Original Message-----
From: Clayton Yendrey <cyendrey@...>
To: main@ap-gto.groups.io
Sent: Wed, Nov 10, 2021 8:46 am
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

Roland,
I don't have an AP mount (on the waiting list for a Mach2), but this sounds very similar to the SDE generated oscillation that has plagued Ioptron's attempt at encoder equipped mounts.  The threads on their issue with this on CN are so numerous that it really deserves its own group... ;-)
Is that any relation to what is occurring here?
"Sub-divisional error is cyclic, occurring with each interval of the scale or scanning pitch (i.e with each signal period), but it does not accumulate and is independent of the scale or travel length. The two primary causes of SDE are mechanical inaccuracies and misalignment between the scale and the read head, although harmonic disturbances can also cause distortions in the sine and cosine signal"

--
Roland Christen
Astro-Physics



--
Brian 



Brian Valente


Allen Ruckle
 

Roland,  
      Here is an image with the results from accessing the mount with APCC to get the list of values requested,
hopefully you have previously solved the issue.

I have a C14 with HyperStar and Mirror less Canon RP. 

Thank you for your help.

PS  I used the mount and telescope tonight controlling everything with my ASIair Pro.

aruckle


Allen Ruckle
 

The attachment apparently didn’t get attached,

maybe this time.

aruckle


Allen Ruckle
 

Roland,

Here is a bit of information, from just before I had the issue with the oscillation of the mount tracking, I rebalanced the mount to eliminate all imbalance.  However the oscillation did not start immediately, but about an hour and a half later.

aruckle 


Brent Boshart
 

It might be nice if a future version of APCC had a slider control for encoder dampening (for each axis) as I frequently switch back and forth with a lighter and a heavier scope. 


Roland Christen
 

?



-----Original Message-----
From: Allen Ruckle <aruckle@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 11, 2021 12:07 am
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

Roland,  
      Here is an image with the results from accessing the mount with APCC to get the list of values requested,
hopefully you have previously solved the issue.

I have a C14 with HyperStar and Mirror less Canon RP. 
Thank you for your help.

PS  I used the mount and telescope tonight controlling everything with my ASIair Pro.

aruckle

--
Roland Christen
Astro-Physics


Roland Christen
 

I sent you instructions in a separate e-mail that will fix this.

Rolando

-----Original Message-----
From: Allen Ruckle <aruckle@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 11, 2021 9:16 am
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

Roland,
Here is a bit of information, from just before I had the issue with the oscillation of the mount tracking, I rebalanced the mount to eliminate all imbalance.  However the oscillation did not start immediately, but about an hour and a half later.

aruckle 

--
Roland Christen
Astro-Physics


Roland Christen
 

Yes, we are working on something like that for all our encoder mounts, including the 1100 and 1600 mounts.

Rolando

-----Original Message-----
From: Brent Boshart <bboshart@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 11, 2021 9:19 am
Subject: Re: [ap-gto] Mach2 with CP five jiggling while tracking

It might be nice if a future version of APCC had a slider control for encoder dampening (for each axis) as I frequently switch back and forth with a lighter and a heavier scope. 

--
Roland Christen
Astro-Physics