DIY roller shades

I thought I'd share a DIY idea I have with the community here.  The irrigation control and garage door control had me thinking that I may try to fabricate some automated roller shades. This has been on my mind a while, but I haven't had much time to dig into it yet. The bright sun and rising temps here in Texas have got me thinking about it again though. It would be great to save on energy costs and have the shades close when I leave for work each day and open when I arrive home.

Here is what I am thinking so far. I could run the system on a 12V power supply. Konnected outputs would have 12V relays to a 12V DC geared motor.

I presume I would have to have a separate konnected output pin and relay for up and down functions. I'm not really familiar with the relay's circuitry so I'm not sure if I can have the "down" standard polarity and "up" reverse polarity relays connected concurrently to the motor terminals.

I would also need to create some kind of device handler to integrate control with Smarthings(Pretty clueless on this part).

Anyone have any suggestions, additions or insight as to where this plan would break down?  Any input is appreciated. I probably wont be able to work on this seriously until June, but I can update this as I go along. 

Also interested in this feed.  Following in hopes that some engineers out there start on this one...