Future Aims and Present Problems

The whole aim behind present ERF developments is to provide a means of control/adaptronics (that is easy to apply and economical) to a mechanism that has to be by its nature flexible in force, displacement or speed and hydraulically operated. Electronic solid-state semiconductor devices and computers are powerful, inexpensive and adequate for many applications in control, and yet their interface with hydraulic machines usually involves a bulky solenoid or an expensive servo-valve, often with a pilot stage and a power su ply. The aim of ER research is to be able to influence a hydraulic mechanism directly with a current low enough to allow the integration of a system made up of electronic transducing and signal-conditioning equipment, computer processors and feedback monitoring, solid-state controllable field-excitation 

At present, the problems of high current density and particularly its sensitivity to temperature, and low yield strength in commercially available fluids 

Finally a word of caution a r, 7-characteristic for an ER fluid will not give exactly the same shape of torque, speed, pressure, or flowrate-curves for an ER device, and viscometers should be designed and operated so that the fluid rather than the device characteristic is measured [101,117]. Other areas of ER fluid development requiring specialist attention include lubrication hysteresis, stabilization and the exclusion of impurities. 

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