Force Control of ER Fluid Based Haptic Device in Virtual Environment

摘要

This paper presents force-feedback control performance of a haptic device using a controllable electrorheological (ER) fluid. A spherical type of joint is devised and its torque characteristic is analyzed by considering Bingham property of ER fluid. In order to embody a human organ into virtual space, a volumetric deformable object is adopted. The virtual object is then mathematically formulated by the shape retaining chain linked (S-chain) model. After evaluating reflection force, computational time, and compatibility with real time control, the virtual environment with the ER haptic device is established by incorporating reflection force and desired position originated from an organ and master, respectively. In order to achieve force trajectories at the haptic device in which the force comes from the virtual space, a sliding mode controller (SMC) is formulated and experimentally realized. Tracking control performances for various operating conditions are presented in time domain, and their tracking errors are evaluated.