Comparison of Field-Controlled Characteristics between ER and MR Clutches

This paper presents torque control characteristics of ER (electro-rheological) and MR (magneto-rheological) clutches. As a first step, Bingham properties of ER and MR fluids are experimentally distilled under the shear mode. A nondimensional model of the clutches is established for reasonable comparison. Two clutches have the same principal design parameters such as outer radius of the disc and electrode gap size. Following the manufacturing of two clutches on the basis of the nondimensional model, field-dependent torque levels are experimentally evaluated. A PID (proportional-integral-derivative) controller is then designed and experimentally realized to achieve desired torque. Both regulating and tracking torque control responses of the two clutches are evaluated and compared. In addition, control durability for torque tracking is undertaken to provide a practical feasibility of the proposed clutches.