Browse Prior Art Database

Numerically Controlled Director

IP.com Disclosure Number: IPCOM000093836D
Original Publication Date: 1966-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Related People

Hoernes, GE: AUTHOR

Abstract

This apparatus controls the positioning of an automatic machine tool.

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Numerically Controlled Director

This apparatus controls the positioning of an automatic machine tool.

Time reference counter 10 is counted up by a 1 mc crystal-controlled oscillator 12. Each axis of movement, only one shown, has a location register 14 which is four BCD digits long. The output of counter 10 is compared with the output of register 14 at compare circuit 16. As counter 10 counts up, it equals the high three digits of register 14 once every 1000 oscillations of oscillator 12, that is, once every millisecond. At the time of equality, compare circuit 16 generates a compare signal which drives a 4-bit overflow counter 18 up by one increment. Counter 18 is counted back down by one increment when a feedback pulse arrives from table 20. The time difference between the occurrence of compare and feedback pulses is proportional to the distance on table 20 to which it is desired to move the machine tool bed. The time interval between countup and countdown of counter 18 is proportional to the error between the theoretical location of the table bed and its actual location as indicated by the time of occurrence of the feedback pulse. The output of counter 18 is fed to logic circuit 22.

The latter determines the sign of the error and sends a pulse-length modulated signal to analog circuit 24. If counter 18 contains 1, 2, 3 or 4, the error is positive. If it contains 9(-1), 8(-2), 7(-3) or 6(-4), the error is negative. Analog circuit 24 integrates the signal and opens valve 28. The latter drives table 20 in the appropriate direction to reduce the error to zero. As table 20 approaches the desired location stored in register 14, the pulses become shorter, valve 28 closes and table 20 comes to a stop at the desired location.

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