INTERACTIVE DYNAMICS WITH HAPTIC DISPLAY Brent Gillespie

Brent Gillespie, Mark Cutkosky ABSTRACT The simulation of virtual environments which are multi-degreeof-freedom presents unique challenges to the designer of control software for haptic display devices. Once the successfully rendered stiffness, damping, and mass elements are interconnected to form multibody systems, a host of controller implementation choices arise. For one, the control law must manifest the dynamics of the simulated multibody system. Further extensions are required if the interconnection topology is allowed to change, as in the case of changing kinematic constraints. The control law must be able to undergo transformations in order to reflect these. We want to include such capabilities in our simulator repertoire, as these are among the most interesting to explore haptically. This paper describes a combined simulation and experimental apparatus for exploring issues in the haptic display of dynamical models. In particular, we address problems in the simulation of changing kinematic constraints with numerical integration methods which have been specialized for realtime mechanical system simulation. Issues in the software design of a haptic display are addressed. A simplified model of the piano action is used as an illustrative example.