Multi Degree-of-Freedom Successive Stiffness Increment Approach for High Stiffness Haptic Interaction

Abstract

In haptic interaction, stability and the object's hardness perception are of great significance. Although numerous studies have been done for stable haptic interaction, however, most of them sacrifice the actual displayed stiffness as a cost of stability. In our recent work, we introduced the Successive Stiffness Increment (SSI) approach whereby the displayed stiffness successively increases with the increase of interaction cycles. It was shown that the haptic interaction was stable and the displayed stiffness was greater than other approaches. This paper extends the SSI approach for multi-DoF haptic interaction. The stiffness increment of the SSI approach depends on the number of interaction cycles which will vary for each axis, therefore, we decouple the interaction by adopting penetration depth-based rendering method using Virtual Proxy (VP). Since the decoupled system has unconstrained end point in the form of moving Virtual Environment (VE), so the boundary conditions are updated in the previously proposed SSI approach at every sample. Phantom Premium 1.5 is used to verify the stability and enhanced displayed stiffness of the proposed approach on a virtual sphere.