Controlled compliance haptic interface using electro-rheological fluids

Electro-rheological fluids (ERFs) are electroactive fluids that experience dramatic changes in rheological properties, in the presence of an electric field. The fluids are made from suspensions of an insulating base fluid and particles on the order of one tenth to one hundred microns in size. In the presence of an electric field, the particles, due to an induced dipole moment, will form chains along the field lines. This induced structure changes the ERF's viscosity, yield stress, and other properties, allowing the ERF to change consistency from that of a liquid to something that is viscoelastic, such as a gel, with response times to changes in electric fields on the order of milliseconds. In this paper the modeling and experimental studies of a novel ERF based haptic interface are presented. Forces applied at a robot end-effector due to a compliant environment are reflected to the remote human operator using this ERF based haptic interface where a change in the system viscosity occurs proportionally to the force to be transmitted. Results of preliminary tests are presented where forces, displacements, pressure and temperature data are measured and analyzed.