US 4,553,078 AGranted

Servo control booster system for minimizing following error

AssigneeThe United States of America as represented by the United States Department of Energy

InventorWilliam L. Wise

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Abstract

A closed-loop feedback-controlled servo system is disclosed which reduces command-to-response error to the system's position feedback resolution least increment, .DELTA.S.sub.R, on a continuous real-time basis for all operating speeds. The servo system employs a second position feedback control loop on a by exception basis, when the command-to-response error .gtoreq..DELTA.S.sub.R, to produce precise position correction signals. When the command-to-response error is less than .DELTA.S.sub.R, control automatically reverts to conventional control means as the second position feedback control loop is disconnected, becoming transparent to conventional servo control means. By operating the second unique position feedback control loop used herein at the appropriate clocking rate, command-to-response error may be reduced to the position feedback resolution least increment. The present system may be utilized in combination with a tachometer loop for increased stability.

Claims6

Dependent claims

A closed-loop feedback control system for precisely controlling the instantaneous position of a machine element along an axis for all operational speeds, in accordance with numerical input commands, said system comprising:

a source of numerical input command signals;
first circuit means for producing feedback signals representing the position of said machine element;
first comparing means for comparing the numerical input command signals from said source with the position feedback signals from said first circuit means;
means responsive to said first comparing means for generating first position correction signals being proportional to the difference between said numerical input command signals and said position feedback signals;
means responsive to the said means for generating first position correction signals to generate an amplified signal output for producing motion of said machine element;
synchronizer means responsive to the numerical input command signals from said source for providing a pulse stream command signal having a pulse rate directly proportional to the input command signal;
second comparing means for continually comparing said position feedback signals with said pulse stream command signal and producing a difference signal representing the difference therebetween;
gating means responsive to said difference signal and second comparing means for producing a command correction signal when a predetermined position correction limit is exceeded;
means for combining the numerical input command signals with the command correction signals to produce a composite numerical input command signal representing second position correction signals;
and
amplifier and motor means responsive to said composite numerical input command signal for driving said machine element along said axis when said predetermined position correction limit is exceeded.

8 more elements

Dependencies are inferred from the claim text.