[...] I dont have much info about the engines (I can ask the manufacturer),
Please do, or see if there's a label on each motor telling the voltage (V) and current (A) they need and whether they're AC or DC.
The control depends on this info.
I was wondering: is there a way to connect these engines to a normal PC under Windows so I can open and close the shutter doors from my computer? Without overriding the normal manual operation.
Where there's a will, there's a way
Actually, the manual controls will just be extra inputs to a power controller, for overriding the automatic control.
I know I have to develop a software (maybe there is something I can buy that is already programmed), but how about the electronics involved? how can I connect the engines to a PC?
There's a number of possible ready made solutions on the software side - try some of what's mentioned here
At the electronics side of things, you can split it up in 3 sections:
PC interface, transmission medium and power control.
For the PC interface, you have to look at what ports are on your PC - parallel, serial, USB or...
If it's a current PC, USB is the likely candidate and you can get a cheap USB control interface with eg. 8 lines in/out or something much larger - it depends on your budget and if you want to prepare for future automation projects.
The transmission medium can be a simple wire, comms over the mains or radio (like X-10 or Z-Wave).
The power control depends on the motors you have. If they're AC mains, a TRIAC control will be the cheap and cheerful solution, with DC, a relay will probably be the easiest for you - but we need the info on the motors to advice properly.
You can either make them fairly "dumb" or use a microcontroller at each power unit - it depends on the level of automation you shoot for and whether you'd like things to run smoothly even if the PC acts up.
To have various positions between fully open an fully closed, you can use optical detection if only a few positions are needed and the PC could just issue a command like "open 50%", and the power driver would then start and keep on until the 50% open is detected.
For data/control integrity, it would be proper to let the power module return a "job done" message when it reaches the point and the software could then be made to alert you if it didn't within a given time frame.
I´m an advanced architect student but I dont know much about automation. Im looking fordward to learn more, I believe this is a good project to start.
Thanks for your time guys and sorry for my english (native lenguage is spanish).
What's an "advanced architect"?
(I get a mind image of weird structures here
Don't worry, your English is very readable, only the term should be "motor", rather than "engine", but we get it anyway
I dont need this to be wireless, Im doing some remodelling on my home and Im wireing everything (inside wall wiring).
Do add 2..3 cat-5 or cat-6 cables, a few extra mains cables, perhaps a heavy gauge cable for 12V or 24V distribution and maybe one or two 75 Ohm coax (assert your needs for extending the home control concept - once you start, you get ideas of automating lots of trivial tasks around the house), make sure that you're set for some time onwards.
A close friend rewired completely and installed only a single cat-5 for control purposes and he quickly ran out of wires, so I had to make him a mux unit to get a lot more down the few wires and we're planning a wireless interface for all his lamp dimmers, the heating and some parts of his access control - you can never have too many wires, copper is better (and cheaper) than other transmission media
I dont need to control speed, but can I control how much the shutter door opens or closes? say, 25% 50% 75% and so on. Not only full open or full close.
Does that involve a different hardware or is just programming?
Of course, but what granularity do you really want/need?
The quarter increments you mention is best solved by either infrared detectors or inductive proximity switches - mechanical switches will be too unreliable and wear down.
If you need fine control over the position, there are several options, but it will be less reliable than a few hard wired positions and I'd think that the most useable would be: small opening (for ventilation), ~30..50% open for serious ventilation and 100% open would cover most needs.
I probably don't need to tell an (advanced) architect student that it's a very good idea to sketch out your plans and adjust and adapt over some days or more, but Just in case...