A Force Bounding Approach for Multi-Degree-of-Freedom Haptic Interaction

Stability and transparency are two major conflicting requirements in haptic interaction systems: some level of transparency is required for providing a realistic feeling while avoiding unstable behaviors that may completely destroy the contact realism of virtual environments or injure the human operator. In this paper, we propose a new multi-degree-of-freedom force bounding approach for a robustly stable and directionally transparent haptic interaction with any virtual environments. The proposed approach is based on two (less and more) conservative sufficient conditions for the passivity condition of sampled-data haptic systems. A less conservative sufficient condition contains, however, memory effect causing contact oscillations due to the accumulation of past remaining dissipation capability during free motion. In order to avoid contact oscillations due to the memory effect, a more conservative sufficient condition may be used for systematically resetting the past accumulated energy. We present experimental results to verify that the proposed approaches make the haptic interaction passive and increase haptic realism significantly.