Stabilized servo motor positioning apparatus

A servo positioning apparatus including a servo motor having a rotary shaft, transducer means for producing first and second periodic signals in response to rotation of the shaft, the first and second signals being substantially 90.degree. out of phase with each other, first and second differentiating means for differentiating the first and second signals, first and second full wave rectifying means for rectifying the differentiated first and second signals and summing means for summing the differentiated and rectified first and second signals to produce a velocity signal having a magnitude corresponding to a rotational velocity of the shaft, characterized by comprising:

• position command means for generating a position signal having a magnitude corresponding to a difference between a present shaft position and a command shaft position;
• reference means for sampling peaks of the first and second signals and producing a reference signal having a magnitude corresponding thereto;
• velocity command means for reducing the magnitude of the reference signal in accordance with the magnitude of the position signal to produce a velocity command signal;
• and
• comparator means for comparing the velocity signal with the velocity command signal and producing a motor drive signal corresponding to a difference therebetween, the motor being energized for shaft rotation by the drive signal.