Contouring control apparatus

Claim 1

POSITIONING APPARATUS FOR CONTROLLING THE MOVEMENT OF THE MEMBER ALONG SEPARATE CO-ORDINATE AXES TO DESCRIBE A DESIRED CIRCULAR PATH AND COMPRISING IN COMBINATION, FIRST AND SECOND SIGNAL SOURCES FOR PRODUCING RESPECTIVE FIRST AND SECOND CO-ORDINATE ACTUAL POSITION SIGNALS, FIRST AND SECOND DIFFERENCING DEVICES RESPECTIVELY OPERATIVE WITH SAID FIRST AND SECOND ACTUAL POSITION SIGNALS AND WITH FIRST AND SECOND INPUT SIGNALS REPRESENTATIVE OF THE COORDINATES OF THE CENTER OF A CIRCLE HAVING THE SAME RADIUS AS SAID DESIRED CIRCULAR PATH FOR PROVIDING FIRST AND SECOND DIFFERENCE SIGNALS, A COMPARISON DEVICE FOR PROVIDING A POSITIONAL ERROR SIGNAL, FIRST GATING MEANS RESPONSIVE TO SAID FIRST ACTUAL POSITION SIGNAL AND OPERATIVE TO TRANSFER SAID FIRST DIFFERENCE SIGNAL TO SAID COMPARISON DEVICE AND SECOND GATING MEANS RESPONSIVE TO SAID SECOND ACTUAL POSITION SIGNAL AND OPERATIVE TO TRANSFER SAID SECOND DIFFERENCE SIGNAL TO SAID COMPARISON DEVICE FOR PROVIDING SAID ERROR SIGNAL, FIRST CONVERTER MEANS RESPONSIVE TO SAID SECOND DIFFERENCE SIGNAL AND A THIRD INPUT SIGNAL REPRESENTATIVE OF A DESIRED CIRCULAR VELOCITY FOR PRODUCING A FIRST CONTROL SIGNAL, SECOND CONVERTER MEANS RESPONSIVE TO SAID FIRST DIFFERENCE SIGNAL AND SAID THIRD INPUT SIGNAL FOR PRODUCING A SECOND CONTROL SIGNAL, AND DRIVING MEANS RESPONSIVE TO SAID FIRST AND SECOND CONTROL SIGNALS AND SAID ERROR SIGNAL FOR CONTROLLING THE MOVEMENT OF SAID MEMBER.