Fine and coarse position servo with frequency comparators

Claim 1

A SYSTEM FOR CONTROLLING A VARIABLE PARAMETER, COMPRISING A COARSE FEEDBACK TRANSDUCER, TWO FINE FEEDBACK TRANSDUCERS, EACH TRANSDUCER BEING ADAPTED TO BE RESPONSIVE TO THE PARAMETER BEING CONTROLLED AND TO GENERATE AN ELECTRICAL FEEDBACK SIGNAL WHOSE FREQUENCY VARIES WITH CHANGES OF THE PARAMETER, THE FREQUENCY OF EACH OF SAID FINE FEEDBACK TRANSDUCERS VARYING WITH CHANGE OF THE PARAMETER THROUGHOUT THE MAJOR PORTION OF ITS VARIATIONS AT A MORE RAPID RATE THAN THE FREQUENCY OF SAID COARSE FEEDBACK TRANSDUCER, A COARSE ERROR DETECTOR CHANNEL CONNECTED TO THE OUTPUT OF SAID COARSE FEEDBACK TRANSDUCER, A FINE ERROR DETECTOR CHANNEL CONNECTED TO THE OUTPUT OF EACH OF SAID FINE FEEDBACK TRANSDUCERS, EACH OF SAID CHANNELS ALSO HAVING AN INPUT ADAPTED TO RECEIVE A COMMAND SIGNAL WITH A FREQUENCY HAVING A PREDETERMINED RELATION TO THE FREQUENCY OF THE FEEDBACK SIGNAL FOR THAT CHANNEL FOR A DESIRED CONDITION OF THE PARAMETER, EACH OF SAID CHANNELS BEING ADAPTED TO PRODUCE AN ERROR SIGNAL HAVING CHARACTERISTICS THAT ARE REPRESENTATIVE OF THE FREQUENCY RELATION BETWEEN ITS COMMAND AND FEEDBACK SIGNALS, ACTUATOR MEANS RESPONSIVE TO SAID ERROR SIGNALS FOR VARYING SAID PARAMETER TO CAUSE ITS ACTUAL CONDITION TO COINCIDE WITH SAID DESIRED CONDITION, SAID COARSE FREQUENCY TRANSDUCER BEING CONSTRUCTED SUCH THAT THE DERIVATIVE OF ITS FREQUENCY-PARAMETER CURVE ALWAYS HAS THE SAME SIGN, AND EACH OF SAID FINE FREQUENCY TRANSDUCERS BEING CONSTRUCTED SUCH THAT THE SIGN OF THE DERIVATIVE OF ITS FREQUENCY-PARAMETER CURVE CHANGES, THE DERIVATIVES OF THE FREQUENCYPARAMETER CURVES OF SAID FINE FEEDBACK TRANSDUCERS CHANGING SIGN AT DIFFERENT TIMES; SAID CHARACTERISTICS OF EACH ERROR SIGNAL COMPRISING ITS PHASE AND MAGNITUDE, THE PHASE INDICATING WHETHER THE FEEDBACK SIGNAL OR THE COMMAND SIGNAL HAS THE HIGHER FREQUENCY AND THE MAGNITUDE INDICATING THE EXTENT OF THE FREQUENCY DIFFERENCE, AND EACH FINE ERROR DETECTOR CHANNEL INCLUDING MEANS FOR REVERSING THE PHASE OF ITS ERROR SIGNAL EACH TIME THE DERIVATIVE OF ITS ASSOCIATED FREQUENCY-PARAMETER CURVE CHANGES SIGN.

Claim 2

A SYSTEM FOR CONTROLLING A VARIABLE PARAMETER, COMPRISING A COARSE FEEDBACK TRANSDUCER, TWO FINE FEEDBACK TRANSDUCERS, EACH TRANSDUCER BEING ADAPTED TO BE RESPONSIVE TO THE PARAMETER BEING CONTROLLED AND TO GENERATE AN ELECTRICAL FEEDBACK SIGNAL WHOSE FREQUENCY VARIES WITH CHANGES OF THE PARAMETER, THE FREQUENCY OF EACH OF SAID FINE FEEDBACK TRANSDUCERS VARYING WITH CHANGE OF THE PARAMETER THROUGHOUT THE MAJOR PORTION OF ITS VARIATIONS AT A MORE RAPID RATE THAN THE FREQUENCY OF SAID COARSE FEEDBACK TRANSDUCER, A COARSE ERROR DETECTOR CHANNEL CONNECTED TO THE OUTPUT OF SAID COARSE FEEDBACK TRANSDUCER, A FINE ERROR DETECTOR CHANNEL CONNECTED TO THE OUTPUT OF EACH OF SAID FINE FEEDBACK TRANSDUCERS, EACH OF SAID CHANNELS ALSO HAVING AN INPUT ADAPTED TO RECEIVE A COMMAND SIGNAL WITH A FREQUENCY HAVING A PREDETERMINED RELATION TO THE FREQUENCY OF THE FEEDBACK SIGNAL FOR THAT CHANNEL FOR A DESIRED CONDITION OF THE PARAMETER, EACH OF SAID CHANNELS BEING ADAPTED TO PRODUCE AN ERROR SIGNAL HAVING CHARACTERISTICS THAT ARE REPRESENTATIVE OF THE FREQUENCY RELATION BETWEEN ITS COMMAND AND FEEDBACK SIGNALS, ACTUATOR MEANS RESPONSIVE TO SAID ERROR SIGNALS FOR VARYING SAID PARAMETER TO CAUSE ITS ACTUAL CONDITION TO COINCIDE WITH SAID DESIRED CONDITION, SAID COARSE FREQUENCY TRANSDUCER BEING CONSTRUCTED SUCH THAT THE DERIVATIVE OF ITS FREQUENCY-PARAMETER CURVE ALWAYS HAS THE SAME SIGN, AND EACH OF SAID FINE FREQUENCY TRANSDUCERS BEING CONSTRUCTED SUCH THAT THE SIGN OF THE DERIVATIVE OF ITS FREQUENCY-PARAMETER CURVE CHANGES, THE DERIVATIVES OF THE FREQUENCYPARAMETER CURVES OF SAID FINE FEEDBACK TRANSDUCERS CHANGING SIGN AT DIFFERENT TIMES; SAID CHARACTERISTICS OF EACH ERROR SIGNAL COMPRISING ITS PHASE AND MAGNITUDE, THE PHASE INDICATING WHETHER THE FEEDBACK SIGNAL OR THE COMMAND SIGNAL HAS THE HIGHER FREQUENCY AND THE MAGNITUDE INDICATING THE EXTENT OF THE FREQUENCY DIFFERENCE, AND EACH FINE ERROR DETECTOR CHANNEL INCLUDING MEANS FOR REVERSING THE PHASE OF ITS ERROR SIGNAL EACH TIME THE DERIVATIVE OF ITS ASSOCIATED FREQUENCY-PARAMETER CURVE CHANGES SIGN.