This giant printer was originally constructed by [Komponent/LAB] in 2006 to print some large-format banners for a festival, but has recently been pulled out of storage and updated for the Venture Cup competition. The system received a few mechanical and software updates and was also mounted on tripods in order to make it fully portable.
Instead of using stepper motors and encoders to directly control the print head as in a typical printer, the entire print axis is turned vertically and the relative lengths of two belts are varied (along with the constant downward pull of gravity) to precisely control movement across the plane. The software uses HPGL plotter files and is able to scale them to fit the available printing area.
Although there are some issues with the print head wobbling due to the rapid accelerations, any printed imperfections appear to be difficult to notice from more than a few feet away. Precision could be further increased by tweaking the software to compensate for such unwanted movements.
Although we can imagine many different applications for such a printer such as architectural or street art, some fine tuning would definitely be required at very large scales and to compensate for wind, etc if done outdoors.
Here are some pictures of the build and there is a short video of it in action after the jump.