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US 4,214,193 AGranted
Digital servo anti-hunt circuit
AssigneeHewlett-Packard Company
InventorMartin K. Mason
Life of this patent
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Abstract
A digital servo system is described in which hunting that would be caused by restoring torque due to resilient coupling to a load is prevented by preventing the transfer of information from the error register to the D/A converter controlling the motor.
Claims1
A digital servo system for controlling the rotation of a motor through a predetermined number of angular increments in response to a series of command pulses, comprising
- means for counting a series of command pulses,
- a motor,
- means for producing a number of position pulses proportional to the number of angular increments through which said motor has rotated,
- means for deriving a digital signal representing the difference between the number of command pulses and the number of position pulses,
- means responsive to said digital signal for applying control voltage to said motor,
- means for providing a first signal when said motor is at rest,
- means for providing a second signal when said digital signal representation is zero, and
- means for preventing at least one of the least significant bits of said digital representation from reaching the means responsive to the digital representation for applying a control voltage to said motor when said first signal indicates the motor is essentially at rest and the second signal indicates that the digital signal represents a zero count.
5 more elements
Dependencies are inferred from the claim text.