Viscous control of homogeneous ER fluid using a variable structure control

Homogeneous electrorheological (ER) fluid is a smart fluid whose appearance viscous coefficient can be controlled by applying an electric field. Therefore, the application of this fluid can create a damping device in a mechanical system. However, the ER effect of the fluid is easily changed by shear rate or temperature variation. In this study, a viscous coefficient control method using a variable structure control is proposed, and the application of the control method to a clutch using homogeneous ER fluid is demonstrated. Further, in order to discuss the effectiveness of the proposed viscous controller, the ER clutch is used for vibration control of the flexible joint arm. Our results show that the viscous coefficient of the clutch was accurately and speedily controlled by the proposed control method. Thus, it is possible to obtain a reliable ER device that is not influenced by variations in this fluid property.