System for controlling the velocity and position of a rotating member

Abstract

Abstract THERE IS DISCLOSED A SYSTEM FOR CONTROLLING THE ROTATIONAL VELOCITY AND PHASE (POSITION) OF A CONTINUOUSLY ROTATING DEVICE SUCH AS A MAGNETIC DRUM. A MEASUREMENT TRAIN OF PULSES IS COMPARED WITH A REFERENCE TRAIN OF PULSES IN A CLOSED LOOP TO LOCK THE ROTATIONAL VELOCITY OF THE DRUM TO THAT DICTATED BY THE FREQUENCY OF THE REFERENCE TRAIN. ONCE DURING EACH FULL ROTATION OF THE DRUM A MEASUREMENT INDEX PULSE IS PROVIDED. THIS MEASUREMENT INDEX IS COMPARED WITH A REFERENCE INDEX PULSE IN A CLOSE LOOP SYSTEM TO PROVIDE POSITIONING (PHASE) CONTROL OVER THE ROTATING DRUM. IN ORDER TO PROVIDE BOTH POSITION AND FREQUENCY CONTROL, SIDE BAND GENERATION IS PROVIDED USING THE REFERENCE SIGNAL FOR TGHE CENTER FREQUANCY. THE FREQUENCY OF THE MODULATING SIGNAL, AND THUS THE DEVIATION OF THE SIDE BAND FROM CENTER FREQUENCY, IS DETERMINED BY THE MAGNITUDE OF DISPLACEMENT BETWEEN MEASUREMENT INDEX SIGNAL AND THE REFERENCE INDEX SIGNAL. THE UPPER OR LOWER SIDE BAND IS SELECTED AS A FUNCTION OF THE DIRECTION OF DISPLACEMENT OF THE MEASUREMENT INDEX SIGNAL FROM THE REFERENCE INDEX SIGNAL. IN ANY CASE, WHEN THERE IS AN INDEX ERROR, A SIDE BAND SIGNAL IS EMPLOYED AS THE COMMAND SIGNAL. THIS COMMAND SIGNAL IS COMPARED WITH THE MAIN MEASUREMENT SIGNAL TO CAUSE THE DRUM TO SPEED UP OR SLOW DOWN UNTIL THE INDEX ERROR IS ELIMINATED. WHEN INDEX SYNCHRONIZATION IUS ACHIEVED, THE MAIN REFERENCE SIGNAL IS EMPLOYED AS THE COMMAND SIGNAL SO THAT THE FREQUENCY OF THE DRUM IS LOCKED TO THAT DICTATED BY THE MAIN REFERENCE SIGNAL. IN ADDITION, ONCE INDEX SYNCHRONIZATION HAS BEEN ACHIEVED, FURTHER POSITION CONTROL IS PROVIDED WITHIN THE SPAN OF A SINGLE MEASUREMENT SIGNAL PULSE BY VIRTUE OF A MODIFICATION TO THE WIDTH OF THE COMMAND SIGNAL PULSES BY AN AMOUNT IN A DIRECTION TENDING TO CAUSE MEASUREMENT SIGNAL PULSES AND MAIN REFERENCE SIGNAL PULSES TO BECOME COINCIDENT IN PHASE.

Inventors

• 👤 Michael S Schiller

Bibliographic Details