Position control system utilizing a coarse analog comparison system with a fine discrimination system

Claim 1

IN A SYSTEM FOR CONTROLLING THE RELATIVE POSITION OF TWO OBJECTS WHEREIN COMMANDED POSITION IS DIGITALLY STORED IN A PLURALITY OF PREDETERMINED GROUPS OF REGISTERS OF VARYING SIGNIFICANCE AND ACTUAL POSITION IS DIGITALLY INDICATED IN A PLURALITY OF CORRESPONDING PREDETERMINED GROUPS OF REGISTERS OF VARYING SIGNIFICANCE, A COMPARISON SYSTEM COMPRISING A PLURALITY OF DIGITAL-TO-ANALOG CONVERSION DEVICES EACH CAPABLE OF PRODUCING AN ANALOG SIGNAL IN RESPONSE TO AN APPLIED DIGITAL SIGNAL, MEANS FOR COUPLING ONE OF SAID CONVERSION DEVICES TO EACH OF SAID COMMAND POSITION REGISTERS RESPECTIVELY, MEANS FOR COUPLING ONE OF SAID CONVERSION DEVICES TO EACH ONE OF SAID ACTUAL POSITION REGISTERS RESPECTIVELY, A PLURALITY OF ANALOG COMPARATORS EACH HAVING FIRST AND SECOND INPUTS AND AN OUTPUT FOR PROVIDING FIRST AND SECOND DIGITAL SIGNALS, MEANS FOR COUPLING SAID INPUTS OF ONE OF SAID COMPARATORS TO EACH OF THE CORRESPONDING ONES OF SAID COMMANDED POSITION AND ACTUAL POSITION CONVERSION DEVICES RESPECTIVELY, AND MEANS COUPLED TO THE OUTPUT OF THE COMPARATOR ASSOCIATED WITH THE REGISTER GROUPS OF LEAST SIGNIFICANCE FOR GENERATING AN ERROR SIGNAL, THE MAGNITUDE OF WHICH IS PROPORTIONAL TO THE DIFFERENCE BETWEEN THE COMMANDED POSITION AND THE ACTUAL POSITION TO PROVIDE AN ERROR SIGNAL SUITABLE FOR PROPORTIONAL CONTROL.