A constraint-based god-object method for haptic display

Haptic display is the process of applying forces to a human "observer" giving the sensation of touching and interacting with real physical objects. Touch is unique among the senses because it allows simultaneous exploration and manipulation of an environment. A haptic display system has three main components. The first is the haptic interface, or display device, generally some type of electro-mechanical system able to exert controllable forces on the user with one or more degrees of freedom. The second is the object model-a mathematical representation of the object containing its shape and other properties related to the way it feels. The third component, the haptic rendering algorithm, joins the first two components to compute, in real time, the model-based forces to give the user the sensation of touching the simulated objects. This paper focuses on a new haptic rendering algorithm for generating convincing interaction forces for objects modeled as rigid polyhedra. We create a virtual model of the haptic interface, called the god-object, which conforms to the virtual environment. The haptic interface can then be servo-ed to this virtual model. This algorithm is extensible to other functional descriptions and lays the groundwork for displaying not only shape information, but surface properties such as friction and compliance.