Augmented-Reality Pendulum

(A Processing program illustrating vibration isolation)

Ludovico Carbone


This sketch is another implementation of the pendulum sketch by Emil Schreiber and it illustrates the dynamics of a multiple pendulum system and the associated seismic isolation capabilities with an enhanced interaction between the user and the computer. To play this sketch, simply download the gw-marker, print it out, run the program and show the marker to your webcam: on the screen you'll see a virtual pendulum which hangs from the marker and follows its motion, and the motion of your hands, as a real pendulum would do.

This method of overlaying computer generated graphics with real-time images is called `Augmented-Reality' and currently finds large applications in many fields from science and technology to computer games to architecture and art. We use it here simply to give an old classic, the pendulum, a new look. More information about the physics involved can be found in this accompanying note (pdf file).

AR Pendulum Screenshot 1 AR Pendulum Screenshot 2

The video below shows the program in action.

This program is provided as a stand-alone application (not as an applet that runs in a browser). To run this application please download the appropriate file, unzip it and start the executable in the AR_pendulum folder. You must have Java installed for the application to work.

With this sketch you can `physically' experience the vibration isolation properties of such a mechanical system: try to move the pendulum suspension (i.e. the marker) horizontally or vertically, or move it at different speeds slow or fast, and see how differently the lower part of the pendulum will respond to your motion and how large - or little - it will oscillate.

This sketch has some additional options:

  • Enter "m" key to release control of the pendulum suspension from the marker to your mouse (and vice versa). In mouse mode you can use your mouse you to grab the pendulum bobs and move them around.
  • Enter "s" key to switch between a `spring-like' suspension wire - as a spring it pulls when it is stretched and it pushes when it is compressed - to a `string-like' wire - as a string, it pulls when it is stretched, but does nothing when it's compressed.
  • The "r" ket stops and resets the pendulum dynamics.
  • The space bar pauses and unpauses the entire sketch.

The program was developed in the Gravitational Wave Group Birmingham, UK. See also our other Processing examples.