Design of PD controller with Electrorheological fluid damper

To realize high precision positioning while not preventing high speed movement of the motor, a functional damper that can control its viscous characteristics in real time is one appropriate solution. Electro-Rheological (ER) fluids provide useful working fluids for the damper because their apparent viscosity can be controlled by the applied electric field. To realize a functional damper manipulated in real time, the modeling and control of the ER fluids is necessary. Moreover, for improved control performance or analysis of the stability of the motor controller including the ER fluid damper, it is necessary to introduce the response characteristics of the fluids when designing the controller. While the formula structure of the response delay has been relatively clear, it was not included in the controller. This paper identifies time delay effects of ER fluids, designs a PD controller for a instance that explicitly considers the fluid´s response delay, and confirms the design by simulation and experiment.