Viscous Coefficient Control of Homogeneous ER Fluid Using a Sliding Mode Control Method

Abstract

Homogeneous ER fluid is one of the smart fluids, having properties by which their apparent viscosity coefficient can be controlled according to the strength of an electric field applied to them. However, the ER effect of the fluid is easily changed by shear rate variation or temperature variation.
In this study, a viscous coefficient control method using Sliding Mode Control is proposed, to enable a more effective use of the ER fluid, and demonstrate the application of the control method to a developed homogeneous ER clutch. Further, this controller is applied to a robot arm with elastic joints, which the clutch is installed in order to study about the effects of the control system.
The results of our experiment clearly show that the viscous coefficient of the clutch has been accurately and speedily controlled to the desirable viscous coefficient by the proposed control method. Therefore, by applying the proposed control method, it is possible to obtain a reliable ER device without being influenced by variations of this fluid property.