A two part description of two digital-hydrostatic servoactuators is presented. The first servoactuator described is based on a digital valve that can be hydraulically or pneumatically powered. The actuator is incremented by discrete volumes of fluid discharged by the valve at a frequency and polarity dependent on the servo error magnitude and sign.
The basic principle of operation of the fluid-powered servoactuator applies to an electrically-powered one. In this version, however, the discrete flow is derived from a digitally controlled pump driven by a constant speed motor. This part of the paper includes a preliminary layout of a dual power-hinge servoactuator which shows that a compact, fully integrated module is feasible.