Automated Dome?

[PhotoGav]

I am on the cusp of hacking down bushes to create space for an observatory. I have been considering the Roll Off Roof vs Dome debate and am really undecided which way to go at this stage. I can see so many advantages to the ROR design, but it also has its share of disadvantages, space for the 'roll off' bit being one. A dome would look great and given that it will be located in a prominent position as our garden is pretty small, looks do matter! The question I struggle to answer with a dome is how complex is it to automate the dome rotation to be in sync with the mount? Does anyone have any particular experience of either or ideally both that would help influence my decision, given that I am an imager and will be looking to enjoy night after night of mammoth imaging sessions, mainly from the comfort of my sofa with TeamViewer!

[mwayne]

I'm sure other more knowledgeable people will chime in later but my understanding is that if you have the right pieces in place it can be done.

 

http://ascom-standards.org/

 

Check out the link above.

[Oddsocks]

I am in the process of swapping from a Skyshed POD to a Pulsar dome with full automation, I decided to buy the expensive ready made Pulsar supplied rotation kit as too many other projects on the go at the same time however you can build all the control parts necessary from diy kits using Velleman USB controllers and interface cards,

https://www.velleman.eu/products/view/?id=404880

these will cost you around £60, then add in the drive motor for the dome (and shutter if wanting full remote control from a different location), encoder to read the dome rotation angle and power supply etc for another £80 depending whether you go for new or second hand scrap motors from wheel chairs, golf buggies etc.

The Lesvedome project site provides plenty of automation instructions and help as well as an ASCOM driver that uses the Velleman project boards, the ASCOM driver is not free but the cost is resonable at €50.

http://www.dppobservatory.net/DomeAutomation/DomeDriver.php

The ASCOM dome driver reads the telescope pointing data and which side of the meridian the mount is pointing then computes the offset required to ensure the slit is fully aligned with the telescope, add in a rain sensor and shutter motor and you can retire to bed and leave the telescope to its pre-programmed observing list and it will shut the dome on completion or if it clouds over and begins to rain.

Of course, full automation like this is a bit more complicated on the software side but basic rotation control is straight forward, you can even build an Arduino based system and find the ASCOM driver available for free at various project forums on the web.

Steppenwolf has been writing a legthy post about fully automating a remote observatory here at SGL and it is a goldmine of useful information!

 

 

 

 

[PhotoGav]

Thank you Oddsocks, I will have a good read through Steve's thread. I knew he was working on that project, but didn't know there was a thread about it.

Good luck with your upgrade to the Pulsar dome. That's the one I've been considering. Will you use MaximDL for full control?

[hughgilhespie]

Hi Photogav,

I am slowly working my way through automating my Pulsar 2.2 metre dome. I have gone down the route of using the Lesvedome.net driver with the Velleman USB breakout board. This is a tried and tested route. However, just to make life more difficult, I decided to use Arduino controlled stepper motors rather than the relays with ordinary brushed dc motors that most people have used.

I am getting there, albeit painfully slowly. However, unless you have well developed masochistic tendencies, I recommend the normal relay route to automation.  

The dome rotation is fairly easily accomplished with the later design of the Pulsar domes as you can glue on timing belt around the internal dome flange. Then a fairly modest motor fitted with a matching gear pinion will provide a very reliable drive. The earlier Pulsar domes without this flange were usually driven by using a rubber wheel to give a friction drive but this solution sometimes had problems with slipping and often two independent drive motors were required.

The Lesvedome solution uses a rotary encoder, either home made or commercial, to provide the dome position and the Lesvedome software takes care of synchronising the dome position with the telescope azimuth.

The dome slit is a more challenging problem to mechanise although from a software point of view it is easier as it only needs to be either open or closed.

So far, I have a working rotation solution but I haven't tried motorising the slit yet.

One advantage of my Arduino based motor control is that it is possible to integrate all the safety checks into the overall control scheme. My system - when finally finished - should be able to automatically close the slit and shut everything down safely if:

It starts raining

Clouds appear

There is a mains power failure

The 'main' Arduino controller stops working

The battery voltage for the slit controller drops beyond a safe level.

The dome rotation gets jammed

Invasion by Klingons

The imaging sequence has finished

So, yes it is all doable and lots of 'fun' in an angst ridden way.

Hope this helps,

Regards, Hugh

 

[derrickf]

I built an automated rotation system for my dome based on the Lesdvedome project some years ago and can confirm that it works really well. I have not automated the opening / closing of the slit mostly because I don't have the mechanical engineering skills to work out a reliable mechanism but I do have cloud and rain sensors that sound alarms and it takes hardly any time to nip outside to close the slit.

The current version of the Lesvedome driver can drive a second USB interface card so there is potential for remote management of power to various devices; this will likely be my next project

HTH

 

Derrick

[PhotoGav]

Thank you Hugh & Derrick, that's good to hear that there are alternative routes to success. As for masochistic tendencies - I am an imager, I know full well how much tinkering and head scratching is involved, whether I can cope with any more is a different question!

Derrick, I see that you are in West Berkshire. If I do decide on the dome route, might I be able to come and see your dome please as you probably aren't too far away from me?

[derrickf]

Sure Gav, I'm between Hungerford and Newbury; I'll be happy for you to visit. just PM me when you are ready.

 

Derrick

[PhotoGav]

11 minutes ago, derrickf said:

Sure Gav, I'm between Hungerford and Newbury; I'll be happy for you to visit. just PM me when you are ready.

 

Derrick

Perfect, thank you. I'm in Marlborough, so not far at all.

[Oddsocks]

2 hours ago, PhotoGav said:

Will you use MaximDL for full control?

I do have MaximDl from the "old" days but I replaced the mount a few years ago with a Paramount MX which is supplied with the SkyX Pro software, the Paramount can't work without it. 

You can still use MaximDL if you want and tell Maxim to use the SkyX as a virtual mount, the SkyX then relays those MaximDl commands to the Paramount MX but it seemed a bit daft having to use so many different pieces of software at once so I "bit the bullet" and bought the camera add-on and dome add-on for the SkyX Pro which now handles the camera and filters and will interface with the dome controller, and just plan to use CCD Commander for sequencing and weather watching. I also have the full version of Pinpoint for plate solving that CCD commander can use instead of the built-in plate solver of the SkyX, I have not been able to get CCD commander to use the SkyX for plate solving directly although it is supposed to be possible but it works fine with Pinpoint.

If things don't work out as reliably as I hope I can always go back to using MaximDL since it will work just as happily with CCD Commander and Pinpoint using The SkyX as a virtual mount, it just means a more complex software environment.

Frightening how fast the costs escalate once you go all out for automation, unless you have the time and inclination for a bit of DIY and programming

[PhotoGav]

Thanks for that Oddsocks. It appears that dome automation is certainly possible, but at a cost in both money and effort. My thoughts start to sway back towards the 'simple' ROR...!

[steppenwolf]

Quote

The current version of the Lesvedome driver can drive a second USB interface card so there is potential for remote management of power to various devices; this will likely be my next project

I also cover this in my Automation thread - mine is fully automated, in fact, I wonder what it is doing right now?

[steppenwolf]

Quote

The current version of the Lesvedome driver can drive a second USB interface card so there is potential for remote management of power to various devices; this will likely be my next project

I also cover this in my Automation thread - mine is fully automated, in fact, I wonder what it is doing right now?

[PhotoGav]

6 minutes ago, steppenwolf said:

I also cover this in my Automation thread - mine is fully automated, in fact, I wonder what it is doing right now?

Well, your thread is enough to put any mere mortal off the idea of fully automating a dome!! The end result is looking pretty great though. Your auto-collected Rosette is just reward for your hard work - it's a beautiful image. I am now of the opinion that dome automation is as complex as I feared, not impossible, but a great deal of effort and tinkering required to get up and running. It also seems as though it is an expensive proposition. I'm not sure if it is the right solution for me. I would love to have a system that works out when to image and do everything required to acquire data, but I'm not sure that I have the skills or the time to put into the project, not to mention the money.

I am now going to turn my attention to a roll off roof observatory for a while, while continuing to dream of automated domes. Thank you all for your invaluable input.

[steppenwolf]

Quote

I am now going to turn my attention to a roll off roof observatory for a while, while continuing to dream of automated domes. Thank you all for your invaluable input.

As a matter of interest, Gav, most of my issues were not 'dome' related so I wouldn't write off a domed observatory although I do agree that they are likely to be more expensive than a ROR.

[PhotoGav]

7 minutes ago, steppenwolf said:

As a matter of interest, Gav, most of my issues were not 'dome' related so I wouldn't write off a domed observatory although I do agree that they are likely to be more expensive than a ROR.

And just when I thought I was making some headway! Reading through your thread it appears that your troubles were 'simply' in getting everything to talk to each other coherently, so as much software related as anything else?

[steppenwolf]

Quote

And just when I thought I was making some headway! Reading through your thread it appears that your troubles were 'simply' in getting everything to talk to each other coherently, so as much software related as anything else?

I fear so, getting all those disparate pieces of software and hardware talking together reliably is the biggest challenge.

To put this all into some kind of perspective, the advantage of an automated ROR is that with regard to the fabric of the observatory itself, there is only the opening of the roof to consider and this is a relatively 'simple' task as all that is required is a motor, a metal chain drive, some relays, diodes and micro-switches  - there is no Azimuth control to consider!

A domed observatory has a more complex aperture to open as it is not a flat surface but a curved one. A domed observatory requires a non-linear azimuth control to ensure that the telescope points through the centre of the aperture as it moves from the east, through the meridian and over to the west but this is relatively easy to organise in software and the hardware itself pretty much works straight out of the box if you use the Pulsar Observatories solution that I chose.

[PhotoGav]

Indeed Steve. I am at the point that just to have an observatory will be a wonderful step forwards. I am having all the pipe dreams of what I would love to have. The process of compromise is in its early stages! I do enjoy just sitting under the stars waiting for the system to do something or other and having a moment to gawp at the sky. A dome would limit the gawp field of view. However, the idea of gathering subs when I didn't even know the system had seen a moment of clarity is rather appealing too.

The story continues...

One certainty is that whichever route I go down, the clouds will still be there in abundance. 

[steppenwolf]

Quote

One certainty is that whichever route I go down, the clouds will still be there in abundance. 

Of that you can be assured, Gav!

[martin_h]

I use the  Lesdvedome project but for a roll off roof, their driver has provision for roll off roof control now, I use it to control a simple garage door opener, also to control my el panel for flats and the power to the "scope room".

 

 

[PhotoGav]

Well, I have swung this way and that on this, but right now I am thinking that perhaps a dome is the right way forwards. A ROR takes up loads more room in the garden for the run off bit, not great as my garden is not huge.

So, the question now is how far do I really have to go down the automation route to successfully image with a dome for long-ish unattended periods? If I get the dome rotation motor, will that be good enough to set in motion and then leave for an hour or three with it tracking happily enough to allow my scope to see the right bit of sky? I don't mind attending the set-up occasionally during an imaging session, at a meridian flip for example. I can then add in more and more automation as desire and budget permit.

[Oddsocks]

Yes,

A simple dome rotation motor set to drive the dome at sidereal speed can be manually aligned to the OTA and the two will happily keep aligned for hours.

You can even do this using a second hand golf-cart/buggy, wheelchair or car window/roof raiser motor and a simple arduino controller for less than a few hundred pounds.

[PhotoGav]

Excellent, thank you Oddsocks.

[hughgilhespie]

Plus One for Oddsocks.

It's the easiest way of getting started. I would recommend using a Step Motor rather than a car windscreen type as you will be able to control the speed much more easily and accurately. A suitable motor is this one http://uk.stepperonline.com/gear-ratio-51-spur-gearbox-high-torque-nema-23-stepper-motor-23hs302804ssg5-p-115.html 

Then you will need a step motor driver like this http://uk.stepperonline.com/24-phase-nema-23-stepper-motor-driver-2450vdc-15a45a-256-microstep-m542t-p-293.html

And finally an Arduino Nano will be fine to control the motor.

You will also need the timing belt and suitable pinion to fit the motor shaft. I reckon you could have sidereal rotation in place for under £300.

If you do decide to go this route I would be happy to give you more information, Arduino sketches etc.

Regards, Hugh

[PhotoGav]

Thank you Hugh. That looks like a frightening route to go down for somebody who has trouble checking the oil on his car! I am looking at the Pulsar 2.2m dome with the Rigel rotation drive unit. It is expensive, but will be fitted by people who know what they are up to and won't leave until it is working!