Movement control servomechanism

Claim 1

A MOVEMENT CONTROL SERVOMECHANISM COMPRISING IN COMBINATION: A MOVABLE MEMBER; ELECTRICALLY CONTROLLABLE DRIVE MEANS; MEANS CONNECTING SAID DRIVE MEANS TO EXERT A FORCE ON SAID MEMBER TO PRODUCE MOVEMENT THEREOF; A SOURCE OF REFERENCE IMPULSES OF PREDETERMINED PERIODICITY; A SOURCE OF CONTROL IMPULSES OF PERIODICITY RELATED TO THE MOVEMENT OF SAID MEMBER; PHASE ERROR MEANS DERIVING A SIGNAL REPRESENTING A PHASE DIFFERENCE BETWEEN APPLIED SIGNALS; CIRCUIT MEANS APPLYING SAID REFERENCE IMPULSES AND SAID CONTROL IMPULSES TO SAID PHASE ERROR MEANS TO DEVELOP A PHASE ERROR SIGNAL; SIGNAL DELAY MEANS OPERABLE TO DELAY APPLIED SIGNALS BY ONE PERIOD OF SAID REFERENCE IMPULSES; CIRCUIT MEANS APPLYING SAID PHASE ERROR SIGNAL TO SAID SIGNAL DELAY MEANS; DIFFERENCE MEANS YIELDING OUTPUT SIGNALS REPRESENTING DIFFERENCES BETWEEN APPLIED SIGNALS; CIRCUIT MEANS APPLYING SAID PHASE ERROR SIGNALS AND SAID DELAYED PHASE ERROR SIGNALS TO SAID DIFFERENCE MEANS TO DEVELOP A PHASE ERROR DIFFERENCE SIGNAL; FIRST ADDING MEANS DEVELOPING A VELOCITY ERROR SIGNAL PROPORTIONAL TO THE SUM OF ONE APPLIED SIGNAL AND OF ONE-HALF A SECOND APPLIED SIGNAL; CIRCUIT MEANS CONNECTING SAID PHASE ERROR DIFFERENCE SIGNAL TO SAID FIRST ADDING MEANS AS SAID ONE SIGNAL; SECOND ADDING MEANS DEVELOPING A FIRST CONTROL POTENTIAL PROPORTIONAL TO THE SUM OF ONE-HALF A FIRST APPLIED SIGNAL AND OF A SECOND SIGNAL; CIRCUIT MEANS APPLYING SAID VELOCITY ERROR SIGNAL TO SAID SECOND ADDING MEANS AS SAID FIRST SIGNAL; CIRCUIT MEANS APPLYING SAID PHASE ERROR SIGNAL TO SAID SECOND ADDING MEANS AS SAID SECOND SIGNAL; NONLINEAR MEANS