Servo control system for the positioning of an apparatus

A servo control system for the positioning of an apparatus comprising, in combination:

• a direct current motor having an input and a shaft, the shaft of said direct current motor having said apparatus connected thereto;
• computing means having an output for generating a plurality of digital command signals, each of which is determinative of a predetermined programmed position in an azimuthal direction to which said apparatus will be moved by said motor at a programmed velocity within a predetermined time period;
• means having an input connected to the output of said computing means, and an output for converting each of said digital command signals to an analog command signal proportional thereto;
• means having an input effectively connected to the output of said converting means, and an output connected to the input of said direct current motor for amplifying each of said analog command signals so as to effect the activation of said direct current motor such that the shaft thereof will rotationally move said apparatus to each programmed position as determined by the digital command signals generated by said computing means;
• potentiometer means effectively connected to the shaft of said direct current motor and having an output for producing at the output thereof an electrical signal indicative of the actual position of said apparatus;
• tachometer means effectively connected to the shaft of said direct current motor and having an output for producing at the output thereof an electrical signal indicative of the actual velocity of said apparatus;
• means having an input connected to the output of said converting means and an output for generating a forward feed enhancement signal in response to each of said analog command signals;
• and
• feedback means effectively connected between the output of said converting means and the input of said amplifying means, said feedback means having first, second, and third inputs, the first of which is connected to the output of said potentiometer means, the second of which is connected to the output of said tachometer means, and the third of which is connected to the output of said generating means;
• for providing, in response to the electrical signal produced by said potentiometer means, a position error signal proportional to the difference between the predetermined programmed position of said apparatus and the actual position of said apparatus, for providing, in response to the electrical signal produced by said tachometer means, a velocity error signal proportional to the difference between the programmed velocity of said apparatus and the actual velocity of said apparatus, for varying, in response to said position error signal and said velocity error signal the voltage level of each of said analog command signals so as to cause the rotational velocity of the shaft of said direct current motor to vary such that said apparatus will attain each predetermined program position within said predetermined time periods, and for combining said forward feed enhancement signal with each of said analog command signals so as to reduce said velocity error signal to a predetermined voltage level such that said servo control system will respond to digital command signals provided by said computing means at frequencies not to exceed a predetermined frequency rate.