In this paper, the importance of the user's primary holding pivot point on the end effector of a haptic interface is discussed. Both theoretical analysis and experimental results demonstrate that this holding pivot point is critical for the correct perception of the haptic properties assigned to the virtual objects. We also study the physical inertia effects of the end effector on the non-uniform stiffness perception of simulated virtual objects. To the best of our knowledge, no such combined consideration of holding pivot point and device structure related inertia has so far been made for works in 6-DOF haptic rendering. We have instrumented the end effector of a haptic interface with a membrane potentiometer to measure the user's primary holding pivot point in real-time. Accordingly, a preliminary adaptive feedback method is developed to render the appropriate forces/torques to compensate for the effects of the end effector's inertia on the haptic stiffness perception.

Many critics of the Java language have pointed performance deficiencies as a barrier to acceptable support of Collaborative Multimedia Systems. This paper presents four MCRLab products, fully written in Java that support collaboration amongst a group of users, and successfully demonstrate that Java collaboration frameworks are not only possible but also can perform at acceptable levels of quality, if designed correctly.