Abstract
This paper deals with a nonlinear optimization of electrohydraulic servomechanism. High-speed accurate positioning servomechanisms have several potential application fields such as those of photographic typesetting machines and automatic assembling or testing machines for semiconductor manufacturing.
In this report an experimental example of optimal responses in an electrohydraulic servomechanism as high-speed accurate positioner is presented. This consists of two servovalves with different nonlinear flow gains, a linear actuator, an inertial load, an optoelectronic displacement detector, a velocity transducer, and an electric control circuit. This device is so designed as to carry only a few kilogram load within a range of 6cm. To get quick and precise responses we have adopted three control modes: the full acceleration mode followed by the mode of controlled closure of each valve and, finally, the negative feedback control mode free from nonlinear instability.
Optimal switching curves from acceleration to deceleration were empirically obtained under reasonably stable conditions. We have thus realized 20∼30msec positioning time with ±5 micrometer accuracy.
