One of the goals I had for this blog when I first set it up was to have a place to post all of the various projects I’ve worked on, both for school and for fun. Well, this particular one has been a long time in the making and is still only partially finished. But then again, it’s hard to ever call a project really finished. Doorbot is a project I’ve been working on for over a year now and I’ve finally had a chance to write it up. First, a little history.
I moved to my current apartment in August 2011, which is located about 4 miles from campus (depending on the route). My previous apartment was less than a mile away and well within walking and biking distance. I began riding my bike to school a lot, and planned to continue riding from my new apartment. I got a new bike and planned out a good route to take, so everything was looking good. There was just one problem: where to store my bike at the new apartment. There are no bike racks, and not really enough room to store it inside. The apartment is at ground level, so we do have a back door and a post that I can lock my bike to. The problem is, the back door is a sliding glass door that doesn’t lock, so to get in the apartment, I have to walk all the way around to the front door. My solution: Build a robot to raise and lower the broomstick that sits in the track of the sliding door, allowing me to avoid walking around to the front door.
Now before I continue, let me emphasize that I am well aware of the irony of trying to build a robot to open my back door, just to save me from walking 100 feet around to the front door. Nevertheless, about this time last year I decided to start constructing version 1.0 of doorbot. My plan was to use the motor from an old erector set to wind up a string tied to the broomstick, and to control the motor via a parallel port connected to my roommate’s old web server, which was set up next to the back door. I set up a website that I could log into from my iPod touch outside the backdoor and send a signal to raise the stick. Everything actually managed to work for a while. It didn’t have much polish, but it got the job done.
Then one fateful day, we had a power outage which killed the web server. This posed a problem and required a complete redesign of doorbot. Doorbot 1.0 was never really finished, so this gave me a chance to try again. The erector set motor had been struggling under the load for quite a while, and the timing mechanism that controlled the motor made the whole thing awkward to use. Next time, I’ll go into the details about the redesign that led to doorbot 2.0.