My homemade design to control Wye Mountain Observatory.

The Controller prototype

The Controller latest development


April 24, 2005 added image of the complete dome control unit ready for remote control. Just by plugging in the Dome position Encoder wheel, Home Position switch, serial cable to dome computer or long serial cable to other location, wiring in the HD supplied Power supply and wiring the motors to the control it is ready to go.

January 2005, setup a wireless link between the observatory and my indoor control room. Used a Linksys WRT54-G router/switch in the home and a DLINK wireless G PCI card in the dome computer. Setup SBIG's EZSRVWIN.exe parallel/USB ethernet server to my SBIG ST-237 camera. Used Technical Innovations DDW Serial-Redirector program between my dome controller and the Digital DomeWorks Control Program (DDWCP). The redirector ran in the dome computer and DDWCP ran indoors. I also setup another serial redirector program on the dome computer for my Losmandy Gemini mount. Another serial redirect program in the house connected the two so I could use Daniel Goerlich's Gemini Control program v1.1 to talk to my mount. I did further experimentation using the ASCOM POTH and Dome control software with my hardware. Using the ASCOM Telescope simulator for DDWCP and wireless to the dome I was able to have the dome follow the virtual telescope. Using the ASCOM POTH connected to the GEMINI driver and DDWCP to the ASCOM POTH i was able to get the dome to follow the GEMINI pointing. There seem to be many possible combinations to try. Now when I can afford a copy of The Sky and Microsoft Windows XP I will test with Tim Longs latest ASCOM DDW driver.

History: I purchased a used Technical Innovations HomeDome HD10 (10ft diameter) January of 2003. It was to include the dome computer control box. Long story short, the seller in Tulsa ripped me off that part. I got the dome installed last September with help from club members. All that stuff is on my site. I had the dome rotation motors, shutter motor and power supply. It was all usable with toggle switches on the power supply from inside the dome.

Development: One of my goals is to have remote astronomy imaging capabilities. For this I decided to attempt my own computer controller. I chose to develop more around semiconductor technology than switches and relays. December 2003 I ordered components and began hardware assembly. Through the months from then to now I have been designing and redesigning my solution in hardware and the necessary software. Last month I completed phase 1.

Phase 1: A manual electronic dome control that allows remote control. This consists of a heavy current (motor) switching and sensor interface box located in the dome. It is controlled from a microcontroller in a box with buttons (see picture). It can interface to the dome inside or from a good distance and function well using a serial or RS-485 cable. This hand box gives a readout of the dome azimuth in degrees the direction the dome is rotating and other information. There are four usable buttons. (CCW) (CW) (STOP) and (PARK). The 12Vdc power plugs in on the left and from top to bottom on the right are (1) dome position encoder input, (2) External serial interface for telescope or dome and (2) Programming and control serial port. As this is a prototype I have since added another connector for interfacing. My plans are to build a more practical design after the debugging dust settles. The next version will have all the dome control components in the box in the dome and a smart remote control box that can be used in dome or in house.

Last evening, 08292004, I got to test early stages of phase 2.

Phase 2: A remote control based on software emulation. I chose to go with the same remote protocol that the manufacturer uses. They offer all their code and workings in the public domain. Not their own dome controller. Last night I setup the Astronomy Common Object Model (ASCOM) platform, a recent Gemini L3 ASCOM driver and the Digital Domeworks Control Program (DDWCP) on my main dome computer. After plugging in all the serial cables, one to Gemini, one to my controller I launched the DDWCP. A few initial configurations and my dome came alive. My telescope was initially pointing at about 20 degrees Azimuth and the dome was at 0 degrees. I enabled "Slave to telescope" in DDWCP and the dome rotated around to center the scope in the dome slot (window). I preceeded to move the scope from location to location some with a GOTO and some with manual pointing (GEMINI controlled) and the dome followed and placed itself in a very good position for the scopes position. This worked whether I turned the scope east or west. WHAT A GREAT FEELING after all these months of late night work.

No it was not all perfect. There were a couple of lockups in my controller. And the DDWCP does not like the way I handle my controller position information when I go CCW past zero. The lower two buttons are on left, (SLAVE) and right (PARK). Pressing the slave button places the control in listen mode. When DDWCP starts up it looks for the control and the two then happily chat. The messages on the LCD work the same as in manual mode. The park button is for manual parking. Pressing park returns the dome to it's park position and optionally opens or closes the shutter. Pressing any button overides the last function. All in all with more programming and tweaking It is looking very promising and is usable even now. Now to get some wire strung from the house to the observatory.

Just had to share... More to come...


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