Negative Inertia: A Dynamic Pointing Function

In-keyboard isometric joysticks can give better pcrforrnancc than mice for mixed typing/pointing tasks. The continuing challcngc is to improve such devices to the point that they arc preferable even for pure pointing tasks. Previous work has improved joystick performance by considering user perception and motor skills. This paper considers the dynamics of the pointing operation. A dynamic transfer function for an isometric joystick is described which amplifies changes in the applied force to increase rcsponsivcncss without loss of control. User tests show a 7.8±3.5% pcrfonnancc improvement over a standard non-dynamic joystick. This feature has been incorporated into the TrackPoint IIIfrom IBM.