Dynamic modeling and parameter identification of a parallel haptic interface

This paper describes the dynamic modeling of a five degree of freedom parallel haptic interface. A novel hand/mechanism partition is used to define the mechanism so that the model can be built up from five identical actuator rod models. The dynamic equations for each rod are first derived using the Newton/Euler equations and are then linearized to obtain an impedance transfer function model for each rod. This model is then used as the basis for the overall mechanism model by noting that parallel impedances add. The transfer function between actuator forces and sensed axial forces at the rod tips, needed for multivariable force control, is derived using the mechanism and rod models. Finally, parameter identification using these models is also discussed.