SERVO CONTROL SYSTEM OPERABLE ON DIGITAL BASIS

摘要

A digital servo control system is responsive to a command signal indicative of a command position of a moveable element and to a phase modulated signal corresponding to the angle of rotation of a motor controlling said moveable element to develop a motor drive signal to position the motor. The system provides control during a velocity control mode and a position control mode, the latter occurring after the moveable element is moved to a predetermined small incremental distance from the commanded position. During the velocity control mode the motor is driven in accordance with a reference velocity selected in dependence upon the position error signal. Following a prescribed time after entry into the position control mode, the position error has added thereto an integration signal which increases in the same sense as the position error.