Mechanical Door Opener

Hey Guys, I purchased an Arduino a few years ago and am finally trying to learn how to use it. I purchased this http://www.amazon.com/gp/product/B004G2KTU4/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 My room has a door that automatically locks when closed. I cannot alter the door, handle, etc since I am in an apartment. I'm trying to devise a plan to meet the following design requirements:

  • Door must be open mechanically from the inside
  • The Arduino must connect to wifi to be operated from an iPhone
  • The door itself cannot be damaged
  • The interior door handle must still be useable to open by hand
  • Some sort of motor is going to have to be involved, but cost should be kept to a minimum

Handle Dimensions: 38" from ground 42" from top L shaped handle that sticks out 3" from door

Any thoughts or design setup suggestions would be amazing. Let me know if any extra info is needed. Thanks!

Do not cross-post. Other thread removed.

I think your biggest problem will be not to damage the door. Any actuating mechanism needs something to react against so it must connect to both the moving handle and some non-moving item - i.e. the door.

Most of those L-shaped handles are held to the door with a plate and afew screws. Perhaps you could unscrew the plate and use slightly longer screws to trap a piece of timber underneath it (4mm plywood or MDF?) which would give you something to attach your actuator to. It could then be removed cleanly when you leave the apartment.

Perhaps you could get a servo with sufficient torque to move the handle. Servos are very easy to use mechanically and also easily controlled with an Arduino.

I presume the Arduino will not be the only way to open the door - just in case it fails?

...R

@Coding Badly, sorry I thought I had deleted the other post.

@Robin2, thank you! This is exactly the type of thinking I needed. While I am not able to disassemble my door handle like you said (it's not feasible with the door handle design) you made me realize that a motor to pull the handle itself is just not feasible.

I had another idea for the setup. The door frame juts out so a "credit card" unlock type thing won't work from the outside. However, the frame is not block it from the inside. I just performed a test with an old charger cable and if I loop something around the latch, close the door, and pull I can unlock the door. I'm thinking I can setup a servo on the inside of my room that I can set to coil up a thread that I set to be looped around the latch. At first I though this may be tricky, since I'd have to set this every time I left the room. Then I realized I could just make the loop bigger and wrap it around the door frame and have it pinned to the wall. Then I can just unpin it when I need to use it. In this way, it would always be set, wouldn't impact opening the door normally, and would cause minimal impact to the door and walls.

If anyone sees any flaws in this new setup I'd love to hear suggestions and critiques!