Automatic control system for vehicles incorporating a ranging system for vehicle traffic safety control

Claim 1

IN A SYSTEM FOR AUTOMATICALLY CONTROLLING THE OPERATION OF A VEHICLE IN ACCORDANCE WITH A TRACTIVE EFFORT CONTROL SIGNAL REPRESENTING THE MOST RESTRICTIVE MODE OF OPERATION CALLED FOR BY (1) A NUMBER OF FIRST ELECTRICAL SIGNALS DERIVED FROM WAYSIDE ELECTRICAL COMMAND SIGNALS REPRESENTING OPERATING DATA SUCH AS PERMISSIBLE MAXIMUM LOCAL ROUTE SPEED LIMITS OR DISTANCE TO A REQUIRED STOPPING POINT AND (2) A SECOND ELECTRICAL SIGNAL REPRESENTING THE RANGE FROM SAID VEHICLE TO AN OBSTRUCTION IN ADVANCE THEREOF, THE COMBINATION COMPRISING: (A) FUNCTION GENERATOR MEANS RESPONSIVE TO SAID SECOND ELECTRICAL SIGNAL FOR PRODUCING A FIRST VELOCITY SIGNAL WHOSE VALUE IS PROPORTIONAL TO A PRESELECTED MAXIMUM VEHICLE VELOCITY FOR THE RANGE; (B) VELOCITY SENSING WHOSE VALUE IS PROPORTIONAL TO THE VELOCITY SIGNAL WHOSE VALUE IS PROPORTIONAL TO THE ACTUAL VELOCITY OF THE VEHICLE; (C) COMPARISON CIRCUIT MEANS RESPONSIVE TO SAID FIRST AND SECOND VELOCITY SIGNALS OPERATIVE TO PRODUCE A VELOCITY-ERROR SIGNAL WHOSE VALUE VARIES AS A FUNCTION OF THE DIFFERENCE IN VALUE BETWEEN SAID FIRST AND SECOND VELOCITY SIGNALS, SAID VELOCITY-ERROR SIGNAL HAVING A FIRST PORTION REPRESENTING AN ACTUAL VEHICLE SPEED GREATER THAN THE PRESELECTED MAXIMUM PERMISSIBLE VELOCITY FOR THE RANGE AND A SECOND PORTION REPRESENTING AN ACTUAL VEHICLE VELOCITY LESS THAN THE PRESELECTED MAXIMUM PREMISSIBLE VELOCITY FOR THE RANGE; (D) CIRCUIT MEANS OPERATIVE TO CONVERT ONLY THE FIRST PORTION OF SAID VELOCITY-ERROR SIGNAL TO AN ALTERNATING CURRENT SIGNAL HAVING AN AMPLITUDE DETERMINING BY THE AMPLITUDE OF SAID FIRST PORTION; (E) MINIMUM QUANTITY SELECTOR MEANS HAVING INPUT MEANS AND OUTPUT MEANS AND BEING OPERATIVE TO PRODUCE A UNIDIRECTIONAL VOLTAGE OUTPUT SIGNAL REPRESENTING THE SMALLEST OF THE ELECTRICAL QUANTITIES APPLIED TO THE INPUT MEANS THEREOF; (F) MEANS FOR APPLYING ALL OF SAID FIRST ELECTRICAL SIGNALS TO THE INPUT MEANS OF SAID MINIMUM QUANTITY SELECTOR MEANS; (G) GATE CIRCUIT MEANS HAVING FIRST AND SECOND INPUT MEANS AND AN OUTPUT MEANS AND BEING OPERATIVE TO PRODUCE FROM A UNIDIRECTIONAL VOLTAGE SIGNAL AND AN ALTERNATING CURRENT SIGNAL APPLIED RESPECTIVELY TO THE FIRST AND SECOND INPUT MEANS THEREOF AN ALTERNATING CURRENT OUTPUT SIGNAL WHOSE AMPLITUDE IS DETERMINED BY THE INPUT SIGNAL HAVING THE SMALLEST VALUE; (H) MEANS APPLYING THE UNIDIRECTIONAL OUTPUT SIGNAL FROM SAID MINIMUM QUANTITY SELECTOR MEANS TO THE FIRST INPUT MEANS OF SAID GATE CIRCUIT MEANS; (I) MEANS APPLYING THE ALTERNATING CURRENT SIGNAL OBTAINED FROM THE FIRST PORTION OF SAID VELOCITY ERROR SIGNAL TO THE SECOND INPUT MEANS OF SAID GATE CIRCUIT MEANS; AND (J) MEANS FOR EXTRACTING AT THE OUTPUT MEANS OF SAID GATE CIRCUIT MEANS AN ALTERNATING CURRENT CONTROL SIGNAL WHOSE AMPLITUDE IS DETERMINED BY THE LESSER AMPLITUDE OF THE ELECTRICAL SIGNALS APPLIED AT THE FIRST AND SECOND INPUT MEANS THEREOF.