A two-ball mouse affords three degrees of freedom

mac @ snowhite.cis.uoguelph.ca We describe a prototype two-ball mouse containing the electronics and mechanics of two mice in a single chassis. Unlike a conventional mouse, which senses x-axis and y-axis displacement only, our mouse also senses z-axis angular motion. This is accomplished through simple calculations on the two sets of x-y displacement data. Our mouse looks and feels like a standard mouse, however certain primitive operations are performed with much greater ease. The rotate tool- common in most drawing programs- becomes redundant as objects are easily moved with three degrees of freedom. Mechanisms to engage the added degree of freedom and different interaction techniques are discussed.