iDoor – iPhone Controlled Hydraulic Door

Opening up the door to your dorm room?

There’s an app for that.

Here’s the story of iDoor, the iPhone controlled hydraulic dorm room door.  Enjoy. Credits to Greg Schroll for most of the hardware.

Life at MIT can be tough. With all the problem sets, and projects taking up time, when I come back to my dorm room to crash, I don’t want to waste time opening doors myself! That’s why my room is outfitted with an iPhone controlled hydraulic door opener and unlocker.  Just tap the “iDoor” app on my phone’s home screen, and the door opens for me.  Its 2009 after all, about time we stopped carrying around shaped bits of metal to open up locked doors.

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When security isn’t my chief concern, I can even ditch the phone altogether and just give iDoor a ’secret’ knock (not so secret any more) and let the vibration sensor trigger the door opening.  See the video above for the full run through.

Technical Overview

Phidget control board

Phidget control board

iDoor is controlled directly from a scrounged up PIII computer running Ubuntu, interfaced with the hardware using the wonderful Phidget 8/8/8 control board.   An early version of the controls used an MIT Happyboard, but for Internet connectivity and development speed, the full PC was chosen.  The software was written in Java using the Phidget library.  (I’ll share the code if you’re interested).

Solenoid valves

Solenoid valves

Piston

Piston

The door is opened by a hydraulic actuator that taps into the sink in the room.   It was built by Greg Schroll in 2006.  The sink inflow tap and outflow tap are connected to a set of 4 one-way solenoid valves.  These valves are connected in such a way that together they can function as a 3-way valve.  Either pushing water one way in the chamber, forcing the piston to open the door, pushing it the other way, forcing the piston to close the door, or diverting water directly from the sink tap to the sink drain (just wasting water!).  The door actuator was custom built by Greg, so get it touch with him if you have questions about its construction.

Solenoid relays

Relays controlling the solenoids

There are two relays between two pairs of solenoids and the 24v power supply.  The relays are tripped from the control board.  One relay opens the door, the other closes it.

Door handle actuator

Door handle actuator

To ‘unlock’ iDoor, a Phidget servo controller has a large Hitech HS-755 servo twist the handle. While opening, it just twists the handle all the way, and when closing, the pulse width is enough to keep the deadlatch from applying too much friction to the strike plate, but still lock. The servo controller can’t output enough power to turn the big servo, so I spliced in a 1.5A 5v cell phone power supply.

Limit switches

Limit switches

There are two limit switches on the door that depress when the door is in its fully closed or fully open state.  The software uses these to know when to close the solenoids.

Interfaces

There’s a re-appropriated handicap button(seen in video) that also ties into the Phidget control board for easy opening when I’m away from my computer or without my phone.  It also functions as an emergency stop button to stop the door while it’s moving.

Vibration sensor

Vibration sensor

For knock activation, there is a vibration sensor at the top of the door positioned so that when the door is closed the sensor part touches the doorframe.  The control software uses the analog input from this sensor to detect my secret knock pattern, and open the door.

I also had my laptop configured so a particular key combination would alternate the door’s state.

A nice property of the whole design is that it can be completely removed from the room without too much work (though who would want too?).

Thoughts of living with it for 9 months…

I spent my senior year living with this door, and besides having to replace a servo, it pretty much worked flawlessy.  The only trouble was my hallmates hacking the door, and random EM noises doing weird things to it. I’m not sure if I’ve actually saved time in the long run, but it was definitely fun. Some of my favorite uses of the door are opening it remotely for friends that need to get stuff out of my room, (though it can be confusing for people that aren’t familiar with it).  If I leave in a hurry, I can also just tell my phone to close my door when I remember later.  Another good trick is opening and closing the door randomly during parties on my hall, confusing bystanders endlessly.

Some things I’ve discovered:

  • When I turn on my speakers, my door handle twitches.
  • Once I left a long analog input cable going into the control board, and it would somehow pick up noise in just the right pattern to trigger the opening sequence.  This always happens at about 4am while I am sleeping.
  • A secret knock, isn’t actually that secure.
  • Handicap buttons aren’t as hard to find as you think
  • Even after 9 months, it never gets old.

33 Comments / Leave a comment

  1. Jack on Jul 2nd, 2009 - 1:06 am Reply this comment

    hey v,
    man If id known MIT kids get to build this kind of shit, i would have worked harder in school…

  2. bren32 on Jul 6th, 2009 - 9:20 am Reply this comment

    Or you could just open the door…

  3. edwina on Jul 6th, 2009 - 11:35 am Reply this comment

    how much did this cost??

  4. Matt on Jul 7th, 2009 - 8:10 am Reply this comment

    I love this idea! My wife and I often have friends and family stay at our place, but we have to be there to let them in to our apartment. Something like this, combined with an answering machine message that returns the correct tone to open the front door would allow anyone visiting to be let in remotely.

  5. fred on Jul 8th, 2009 - 7:03 pm Reply this comment

    Not knocking your efforts or anything, but wouldn’t have been somewhat simpler and more elegant just to install an electric strike in the door frame instead of going through the trouble of building a door handle actuator? The added bonus, of course, is that you get to use the door handle as intended…

  6. DEI on Jul 10th, 2009 - 7:37 am Reply this comment

    Whatever…. we had this at Caltech 10 years ago. Typical MIT. Slow, but steady.

  7. admin on Jul 10th, 2009 - 3:06 pm Reply this comment

    man, caltech must be pretty tight with steve jobs if they had an iphone ten years ago =)

  8. hl2run on Jul 11th, 2009 - 10:49 am Reply this comment

    Just awesome !

  9. guillermo on Jul 11th, 2009 - 5:18 pm Reply this comment

    lol, I’m in Europe and I thought that Calltech-MIT fights only are in the movies.

    The hack is very cool and useful!. I lived with some disabled people at the residence hall and this kind of mechanism controlled using their phone would make their life more easier.

    Congrats!

  10. jay on Jul 16th, 2009 - 4:23 am Reply this comment

    This might have some interesting applications for the disabled community…I have asked a friend of mine from Inclusion Solutions to take a look. Very cool.

  11. patrick on Jul 16th, 2009 - 4:49 am Reply this comment

    hey this is really cool. Have you thought about getting this into a retail environment or packaged for distribution?

    I wonder what the cost might be compared to a typical automated door. Automating doors has been cost prohibitive right now for most small businesses – it would be great if there were something to offer that was practical and cost effective…

    good work… check out http://www.thebigbell.com to see some of our little inventions… jay thanks for sending me here.

  12. valve actuators on Jul 24th, 2009 - 2:18 am Reply this comment

    Complex control systems using valves requires an automatic control based input of an actuator. The actuator strokes the valve allowing the valve to be positioned accurately and allowing control over a variety of requirements.

  13. Kinsey on Oct 2nd, 2009 - 2:37 pm Reply this comment

    This is awesome. Maybe I should look into going to MIT.
    This is the reason I want an iPhone. I need more reasons to be lazy.

  14. Fictage on Oct 3rd, 2009 - 10:50 pm Reply this comment

    I have the original iphone, and it’s unlocked so I dont want to update it or it will brick, but some games require at least version 2.0, so how do I find out if I have that or not? Thanks.

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  15. Raffaele Pio on Nov 15th, 2009 - 5:59 am Reply this comment

    Wow!!!!!!!
    You’re a genie!!!!!
    Wonderful!

  16. Fictage on Dec 12th, 2009 - 7:12 pm Reply this comment

    I have sprint and I heard the new Instinct will be close to the iphone but will it have the real internet like the iphone does?

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  17. Fictage on Dec 12th, 2009 - 7:20 pm Reply this comment

    I live in canada, but want to buy an iPhone in Seattle and then unlock it, which is now possible. How do I buy one without having to sign any sort of contract?

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  18. andré on Dec 22nd, 2009 - 6:38 am Reply this comment
  19. Janus on Dec 28th, 2009 - 3:03 pm Reply this comment

    is it possible to share some info about the actuator, the solenoids and the tubing?? i am really interested, thanks!

  20. iPhone News on Jan 3rd, 2010 - 11:12 am Reply this comment

    I love your posts and I am subscribing to your blog now ! Do you use dofollow ? super

  21. Michael on Jan 15th, 2010 - 9:34 pm Reply this comment

    Hey- is the app actually available or did you build it from scratch? If it’s published, is it also on Sprint’s app market? Because I have a Palm Pre that would make my dorm a lot easier to manage…

  22. admin on Jan 18th, 2010 - 1:29 pm Reply this comment

    Hey Michael,

    The app is actually just a special link that triggers the door. It wouldn’t be much use to you I promise! =)

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