Successive Stiffness Increment Approach for High Stiffness Haptic Interaction

Abstract

This paper proposes a method to further enlarge the displayed stiffness range of the impedance-type haptic interfaces. Numerous studies have been done for a stable haptic interaction in a wide impedance range. However, most of the approaches sacrifice the actual displayed stiffness as a cost of stability. A novel approach, which successively increases the stiffness as the number of interaction cycle increase, is presented. The stiffness is sequentially modulated from a low value to a high value, close to the desired stiffness while maintaining stability. This sequential stiffness increment was possible because the proposed approach guarantees the convergence of the penetration distance and increases the feedback force with every successive interaction cycle. The main advantage of the proposed approach over conventional approaches is that this approach allows much larger actual displayed stiffness than any other approach, such as time-domain passivity approach, force bounding and energy bounding approach. Experiments with PHANToM Premium 1.5 evaluate the performance of the proposed approach, and compare the actual displayed stiffness with other approaches.