A low-cost haptic feedback trackball device for providing haptic feedback
to a user for enhancing interactions in a graphical environment provided
by a computer. The trackball device includes a sensor device that detects
the movement of a sphere in two rotary degrees of freedom. An actuator
applies a force preferably along a z-axis perpendicular to the plane of
the surface supporting the device, where the force is transmitted through
the housing to the user. The output force is correlated with interaction
of a controlled graphical object, such as a cursor, with other graphical
objects in the displayed graphical environment. Preferably, at least one
compliant element is provided between a portion of the housing contacted
by the user and the support surface, where the compliant element
amplifies the force output from the actuator by allowing the contacted
portion of the housing to move with respect to the support surface. The
force can be an inertial force, contact force, or a combination of forces
that provide tactile sensations to the user.