Method and apparatus for measuring velocity and position in servo systems
First Claim
1. A method for measuring the velocity of a servo shaft driven cyclically by a motor, without employing a tachmeter, comprising the steps of:
- producing from movement of said shaft a pair of overlapping square-wave signals in quadrature with transitions expressible in Gray code for each cycle,producing from a clock a large number of evenly spaced clock pulses per a selected number of quadrature transitions,reading the number of clock pulses between two selected quadrature transitions, anddividing the total number of quadrature transitions between said selected transitions by the total number of clock pulses during the same time.
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Abstract
Method and apparatus for measuring the velocity, whether rotary or reciprocating, of a servo shaft driven by a motor, without employing a tachometer. From the movement of the shaft is produced a pair of signals in quadrature, with transitions expressible in Gray code for one cycle as 00, 01, 11, 10 and then back to 00. Meanwhile, a clock provides a large number of evenly spaced counts per selected quadrature transitions. The number of counts between two selected quadrature transitions is read and the total number of quadrature transitions between the selected transitions is divided by the total number of counts during the same time.
59 Citations
16 Claims
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1. A method for measuring the velocity of a servo shaft driven cyclically by a motor, without employing a tachmeter, comprising the steps of:
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producing from movement of said shaft a pair of overlapping square-wave signals in quadrature with transitions expressible in Gray code for each cycle, producing from a clock a large number of evenly spaced clock pulses per a selected number of quadrature transitions, reading the number of clock pulses between two selected quadrature transitions, and dividing the total number of quadrature transitions between said selected transitions by the total number of clock pulses during the same time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for measuring the velocity of a servo shaft driven by a motor, without employing a tachometer, comprising:
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quadrature means for producing from movement of said shaft a pair of overlapping square-wave signals in quadrature with transitions expressible in Gray code, clock means for providing a large number of evenly spaced clock pulses per a selected number of quadrature transitions, reading means for determining the number of clock pulses between two selected quadrature transitions, and computer means for dividing the total number of quadrature transitions between said selected transitions by the total number of clock pulses during the same time. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for measuring the velocity and position of a servo shaft driven cyclically by a motor, without employment a tachometer, comprising the steps of:
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producing from movement of said shaft a pair of overlapping square-wave signals in quadrature with transitions expressible in Gray code for each cycle, producing from a clock a large number of evenly spaced clock pulses per a selected number of quadrature transitions, dividing the total number of quadrature transitions between said selected transitions by the total number of clock pulses during the same time to determine the velocity of the shaft, utilizing the number of quadrature transitions between the selected quadrature transitions to update the position of the shaft relative to the latest quadrature transition. - View Dependent Claims (16)
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Specification