Page 147 - Servo Motors and Industrial Control Theory -

142 8 Actuators Based on Electro-Rheological Fluid

The steady state and dynamic properties of ER fluids in flow and shear modes
were discussed. This is useful in design of power supply and designing closed loop
ER devices. The mathematical model of ER fluid in flow made was derived. In
shear mode, a similar model may be derived. This was left to interested readers to
derive the mathematical model of ER fluid in shear mode. These models help the
designer to study the closed loop behavior of the device that is being designed.
There are other properties of ER fluid which should be investigated before de-
signing a system. These are the abrasiveness, durability, and repeatability and sta-
bility of ER fluids. Another important property of ER fluids is the temperature de-
pendency. It is known that as the temperature of ER fluid increases, the current rises
rapidly. In flow mode, the fluid temperature was kept constant by a cooling system.
In shear mode, the experiment was conducted for a short period of time. This is an
area of research that must be conducted to find out that the temperature affects the
dynamic behavior of the fluids.