I’ve been working with my brother-in-law, Fred, for the last while, helping him out with a project. He’s always been a big Star Trek fan, and he wanted to upgrade a door he had to one done in the style of a space or sci-fi television show. We decided to make it air-powered, and I set to work learning about pneumatics and micro-controllers.
I shot this video last night to show you the current state of the project.
In a nutshell, this is a custom door (based on adding material to a hollow-core door) on sliding pocket-door hardware. Instead of manually sliding the door open, both halves are attached to air cylinders. The air cylinders have an air hose on each end – one to extend the rod, and one to retract it. A “Five Port, Four Way” air solenoid directs air from a compressor to one side or the other of the air cylinder, opening or closing the door. Power to the air solenoids comes from a pair of relays, which are controlled by an Arduino Uno micro-controller. Basic arcade style buttons send a signal to the micro-controller.
As it is, the air-powered doors work great, they just happen to be manually controlled by pressing a button.
The master plan is to fully automate the system. Since a micro-controller is already doing the actual control, all we need to do is add sensors and programing to make the doors open and close with some “IF…THEN….” programming statements. On the other hand, that’s actually harder than you think. This door is between a garage and a workshop. On the workshop side, the walking path is at a right angle to the door, but on the other side it’s a straight line. What happens when somebody pulls a car in to the garage?
It actually takes some clever design and planning to make the door open when you want it to, but NOT open the rest of the time. On television shows and movies, a human stage hand is usually pulling a rope to open the doors at just the right time. In our system, just a dumb computer will have to figure it out. Essentially, we’re trying to keep this from happening.
In the end, it might take several sensors of different types working together. Besides that, there should be some sort of safety mechanisms to keep pets or small children from opening the door as well as to prevent it from closing on them.
We HAVE experimented a bit with using a timer feature. By pressing one button, the doors open, pause for a set amount of time (a few seconds,) and then close. Overall, that worked well and was simple. The main downside is that didn’t allow for KEEPING the door open, and there was nothing stopping the door from closing on a person. (Just to be clear, the door isn’t so powerful that it will crush a person…)
Ideally, I think the door needs three modes – Fully Automatic, Manual Stay Open, and Manual Stay Closed. The Automatic version would keep the doors closed unless a person walked up to them with intent to walk through the doorway. The manual modes are self-explanatory, they would just be an override to hold the door open or shut.
As it is at the moment, the doors are working well for Fred. They are simple, reliable, and look cool.
Also in the video, the decorative trim of the door wasn’t installed. You can see it leaned against the wall to the bottom left of the door.
The door is very functional in that it is insulated and between a heated and unheated workspace.
Keep your eyes peeled for future updates when we add some automation! If you are a master of the micr0-controller and know of some good code for automation and ideas for safeties, send them our way!
Until next time, stay charged up!
-Ben
PS: The original information about this project is located at: http://ecoprojecteer.net/star-trek-doors/
