Web-controlled car launcher
Visitors to our family blog can launch a car from our closet for our toddler to play with. I built a simple gravity-powered car launcher that is controlled by the web site. Clicking "Launch Car Now!" on the web site results in a sound clip from the movie "Cars" playing in our living room, followed by a car shooting out from under the coat closet door. The website uses a bit of PHP to send an email to my wife's computer, which happens to sit in the living room next to the coat closet. I created a filter in Apple Mail to run an AppleScript when a correctly coded email comes through. The AppleScript pauses iTunes and raises the system volume of the computer before activating a small applet I wrote in the Processing language. The Processing applet plays a bit of Lightning McQueen (main character in "Cars") psyching himself up before a big race. The applet then sends an "l" to the serial port, where the car launcher's Basic Stamp II microcontroller is patiently waiting. The BSII opens the sliding garage door on the launcher exactly one bay. There are five bays, for five cars. I set up little tabs to interrupt an infrared beam as the edge of each opening is reached. Once a given bay is open, gravity pulls the toy car out and down the ramp. Momentum carries it under the closed closet door and across the floor to the excited toddler. After receiving each launch command (each clicked "Launch Car Now! from the web site), the launcher will release one car and then wait for another command, progressing until the door is completely open and all cars have been released. The launcher door will then close and wait to be reloaded. The PHP on the web server makes sure the "Launch Car Now!" link is only available during usual playtime hours and also limits the number of cars launched to five per day. The table on which the launcher is sitting was another of my weekend projects, a nice roomy table for the little guy's wooden train set.