Patent ID: 6851261

Claim:
A servoactuator for selectively controlling the movement of an output member in two directions in response to a command signal, comprising: an electric motor having a rotatable output shaft; a motor controller arranged to provide a drive current to said motor for controllably rotating said output shaft; a first transmission mechanism operatively arranged to displace said output member in either direction at a nominal first ratio with respect to said motor output shaft; a hydrostatic second transmission mechanism operatively arranged to displace said output member in either direction at a nominal second ratio with respect to said motor output shaft; a transfer mechanism operatively arranged to selectively couple said motor output shaft to said output member either through said first transmission mechanism to impart a high-speed low-force drive to said output member, or through said second transmission mechanism to impart a low-speed high-force drive to said output member; at least one feedback transducer capable of measuring one of the force, displacement or velocity of said output member, and a servo control loop closed about said motor, controller, transmission mechanisms, transfer mechanism, feedback transducer and output member for selectively controlling at least one of the position, velocity or force of said output member as a function of said command signal.