A force bounding approach for stable haptic interaction

Stability is a major requirement in haptic interaction since unstable behavior impairs realism and may injure the human operator. In this paper, we propose a force bounding approach by which a robustly stable haptic interaction is made possible for any (linear, nonlinear, delayed etc.) virtual environments. Based on the passivity condition for sampled-data haptic systems, a necessary and sufficient condition for the force that can be passively displayed is derived. It contains, however, memory effect due to the accumulation of past remaining dissipation. In order to avoid contact oscillations by the memory effect, a simple reset rule is applied. In addition, a braking pulse is combined with the force that is bounded by the proposed approach in order to increase initial contact realism for stiff environments. Experimental results are presented to verify that the proposed approach makes the haptic interaction passive and increases haptic realism.