This paper describes a new concept in pulse controlled motor and preci
sion linear actuator techniques. Piezo translators [PZT] employed to p
rovide reciprocating primary motion are connected to a load via a cont
rollable electrorheological fluid [ERF] dutch to form a programmable s
peed and step-width drive. Ideal considerations are used to quantify t
he limiting potential of the drive and details are given of its develo
pment and progress.