Passive velocity filtering for haptic applications with wave control

This paper introduces a passive velocity filtering technique for multirate haptic applications with wave variable control. In the proposed method, velocity is estimated via Euler´s method and is filtered in the wave domain using a filter bank-like structure placed in the communications. The paper derives the passivity condition for the wave domain communications with the filter bank, and uses it to set up a minimax optimization which yields the velocity filter. Frequency domain analysis of haptic interaction in a slowly updated virtual environment predicts that the proposed wave domain velocity filter increases the transparency of the interaction. Experiments in which a Novint Falcon haptic device touches a slowly updated virtual wall show significantly less noise in the force feedback provided to the user.