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Title: Interpolator for numerically controlled machine tools

Abstract

A digital differential analyzer circuit is provided that depending on the embodiment chosen can carry out linear, parabolic, circular or cubic interpolation. In the embodiment for parabolic interpolations, the circuit provides pulse trains for the X and Y slide motors of a two-axis machine to effect tool motion along a parabolic path. The pulse trains are generated by the circuit in such a way that parabolic tool motion is obtained from information contained in only one block of binary input data. A part contour may be approximated by one or more parabolic arcs. Acceleration and initial velocity values from a data block are set in fixed bit size registers for each axis separately but simultaneously and the values are integrated to obtain the movement along the respective axis as a function of time. Integration is performed by continual addition at a specified rate of an integrand value stored in one register to the remainder temporarily stored in another identical size register. Overflows from the addition process are indicative of the integral. The overflow output pulses from the second integration may be applied to motors which position the respective machine slides according to a parabolic motion in time to produce amore » parabolic machine tool motion in space. An additional register for each axis is provided in the circuit to allow "floating" of the radix points of the integrand registers and the velocity increment to improve position accuracy and to reduce errors encountered when the acceleration integrand magnitudes are small when compared to the velocity integrands. A divider circuit is provided in the output of the circuit to smooth the output pulse spacing and prevent motor stall, because the overflow pulses produced in the binary addition process are spaced unevenly in time. The divider has the effect of passing only every nth motor drive pulse, with n being specifiable. The circuit inputs (integrands, rates, etc.) are scaled to give exactly n times the desired number of pulses out, in order to compensate for the divider.« less

Inventors:
 [1];  [2];  [3]
  1. Clinton, TN
  2. Oak Ridge, TN
  3. Knoxville, TN
Issue Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
OSTI Identifier:
862597
Patent Number(s):
3969615
Assignee:
United States of America as represented by United States Energy (Washington, DC)
Patent Classifications (CPCs):
G - PHYSICS G05 - CONTROLLING G05B - CONTROL OR REGULATING SYSTEMS IN GENERAL
DOE Contract Number:  
W-7405-ENG-26
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
interpolator; numerically; controlled; machine; tools; digital; differential; analyzer; circuit; provided; depending; embodiment; chosen; carry; linear; parabolic; circular; cubic; interpolation; interpolations; provides; pulse; trains; slide; motors; two-axis; effect; tool; motion; path; generated; obtained; information; contained; block; binary; input; data; contour; approximated; arcs; acceleration; initial; velocity; values; set; fixed; bit; size; registers; axis; separately; simultaneously; integrated; obtain; movement; respective; function; time; integration; performed; continual; addition; specified; rate; integrand; value; stored; register; remainder; temporarily; identical; overflows; process; indicative; integral; overflow; output; pulses; applied; position; slides; according; produce; space; additional; allow; floating; radix; increment; improve; accuracy; reduce; errors; encountered; magnitudes; compared; integrands; divider; smooth; spacing; prevent; motor; stall; produced; spaced; unevenly; passing; nth; drive; specifiable; inputs; rates; etc; scaled; exactly; times; desired; compensate; pulses produced; circuit provides; numerically controlled; information contained; divider circuit; pulse train; machine tools; output pulses; motor drive; output pulse; machine tool; input data; pulse trains; controlled machine; /700/318/

Citation Formats

Bowers, Gary L, Davenport, Clyde M, and Stephens, Albert E. Interpolator for numerically controlled machine tools. United States: N. p., 1976. Web.
Bowers, Gary L, Davenport, Clyde M, & Stephens, Albert E. Interpolator for numerically controlled machine tools. United States.
Bowers, Gary L, Davenport, Clyde M, and Stephens, Albert E. Thu . "Interpolator for numerically controlled machine tools". United States. https://www.osti.gov/servlets/purl/862597.
@article{osti_862597,
title = {Interpolator for numerically controlled machine tools},
author = {Bowers, Gary L and Davenport, Clyde M and Stephens, Albert E},
abstractNote = {A digital differential analyzer circuit is provided that depending on the embodiment chosen can carry out linear, parabolic, circular or cubic interpolation. In the embodiment for parabolic interpolations, the circuit provides pulse trains for the X and Y slide motors of a two-axis machine to effect tool motion along a parabolic path. The pulse trains are generated by the circuit in such a way that parabolic tool motion is obtained from information contained in only one block of binary input data. A part contour may be approximated by one or more parabolic arcs. Acceleration and initial velocity values from a data block are set in fixed bit size registers for each axis separately but simultaneously and the values are integrated to obtain the movement along the respective axis as a function of time. Integration is performed by continual addition at a specified rate of an integrand value stored in one register to the remainder temporarily stored in another identical size register. Overflows from the addition process are indicative of the integral. The overflow output pulses from the second integration may be applied to motors which position the respective machine slides according to a parabolic motion in time to produce a parabolic machine tool motion in space. An additional register for each axis is provided in the circuit to allow "floating" of the radix points of the integrand registers and the velocity increment to improve position accuracy and to reduce errors encountered when the acceleration integrand magnitudes are small when compared to the velocity integrands. A divider circuit is provided in the output of the circuit to smooth the output pulse spacing and prevent motor stall, because the overflow pulses produced in the binary addition process are spaced unevenly in time. The divider has the effect of passing only every nth motor drive pulse, with n being specifiable. The circuit inputs (integrands, rates, etc.) are scaled to give exactly n times the desired number of pulses out, in order to compensate for the divider.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1976},
month = {1}
}

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