Passive Virtual Fixtures Based on Simulated Position-Dependent Anisotropic Plasticity

This paper presents an approach for producing virtual fixture based on simulated plasticity, which can be used for assisting precise manual manipulations performed by human users through haptic interfaces. The fixture acts as a guide to help path-tracing tasks and as a wall for preventing a tool from entering a specified region, but the user can move against the fixture by intentionally producing a force larger than a predetermined yield force. The advantage of the proposed virtual fixture is that it is always passive and it acts as a hard fixture when the user´s force is smaller than the yield force. The algorithm was demonstrated through experiments using an impedance-type haptic interface.