Rendering a Rigid Virtual World through an Impulsive Haptic Interface

This paper deals with the haptic rendering of collisions between a human operator and rigid objects in a virtual environment. The focus being on high-velocity impacts on a rigid wall. After discussing the importance of velocity measurements in contrast to force measurements, a new haptic device is introduced. The new device is capable of applying directly an ´impulse´ to the operator, similar to collisions occurring in the real world. Based on a Poisson-model of the rigid virtual object, the necessary change of momentum of the operator´s hand is being estimated online. A momentum wheel, under velocity-control, is engaged through an electromagnetic toothed clutch, at the estimated instant of impact. The resulting immediate change in momentum is thought to be essential for giving interactions with rigid virtual objects a realistic feel. Rather than generating so-called ´impulsive forces´ with big motors, this approach relies only on small motors and is thus intrinsically safer. Experiments are performed on a one-degree of freedom setup. Conclusions are drawn and future directions of this research are sketched