US3668500A — Numerical servo motor control system

Claim 1

Independent Claim 190 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising, for each axis: feedback counter means for providing an output representatiVe of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said following command counter into a count state representative of said second position; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce a difference signal indicative of a phase difference in said outputs; means responsive to the difference signal output of said means for comparing for enabling motion of said machine tool in the presence of said difference signal; means for changing the count of said command counter at a first rate; and means for changing the count of said feedback counter at a second rate determined by said first rate and the extent of machine tool motion.

Claim 2

Independent Claim 190 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising, for each axis: feedback counter means for providing an output representatiVe of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said following command counter into a count state representative of said second position; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce a difference signal indicative of a phase difference in said outputs; means responsive to the difference signal output of said means for comparing for enabling motion of said machine tool in the presence of said difference signal; means for changing the count of said command counter at a first rate; and means for changing the count of said feedback counter at a second rate determined by said first rate and the extent of machine tool motion.

Claim 3

Independent Claim 240 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising, for each axis: feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second postion for placing said command counter into a count state representative of said second position; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce difference signals indicative of a phase difference in said outputs; a source of machine tool motion command signals; means for moving said machine tool responsive to said machine tool motion command signals; means responsive to said difference signals for enabling said machine tool motion command signals to be applied from said source to said means for moving said machine tool; means for changing the count of said command counter at a first rate; means for changing the count of said feedback counter at a second rate determined by said first rate and the extent of machine tool motion; and means for terminating the application of said motion command signals to said means for moving said machine tool responsive to said difference signals attaining a predetermined minimal value.

Claim 4

Independent Claim 240 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising, for each axis: feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second postion for placing said command counter into a count state representative of said second position; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce difference signals indicative of a phase difference in said outputs; a source of machine tool motion command signals; means for moving said machine tool responsive to said machine tool motion command signals; means responsive to said difference signals for enabling said machine tool motion command signals to be applied from said source to said means for moving said machine tool; means for changing the count of said command counter at a first rate; means for changing the count of said feedback counter at a second rate determined by said first rate and the extent of machine tool motion; and means for terminating the application of said motion command signals to said means for moving said machine tool responsive to said difference signals attaining a predetermined minimal value.

Claim 5

Independent Claim 265 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising, for each axis; feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said command counter into a count state representative of said second position; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce difference signals indicative of a phase difference in said outputs; a source of machine tool motion command signals; means for moving said machine tool responsive to said machine tool motion command signals; means responsive to said difference signals for enabling said machine tool motion command signals to be applied from said source to said means for moving said machine tool; means for generating a motion indicating signal responsive to each increment of motion of said machine tool; a source of oscillations; means for applying oscillations from said source to said command counter to alter its count responsive thereto; means modulating said oscillations with said motion indicating signals; means for applying said modulated oscillations to said feedback counter to alter its count Responsive thereto; and means for terminating the application of said motion command signals to said means for moving said machine tool responsive to said difference signal attaining a predetermined minimal value.

Claim 6

Independent Claim 265 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising, for each axis; feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said command counter into a count state representative of said second position; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce difference signals indicative of a phase difference in said outputs; a source of machine tool motion command signals; means for moving said machine tool responsive to said machine tool motion command signals; means responsive to said difference signals for enabling said machine tool motion command signals to be applied from said source to said means for moving said machine tool; means for generating a motion indicating signal responsive to each increment of motion of said machine tool; a source of oscillations; means for applying oscillations from said source to said command counter to alter its count responsive thereto; means modulating said oscillations with said motion indicating signals; means for applying said modulated oscillations to said feedback counter to alter its count Responsive thereto; and means for terminating the application of said motion command signals to said means for moving said machine tool responsive to said difference signal attaining a predetermined minimal value.

Claim 7

Dependent Claim 162 words

A system as recited in claim 3 wherein said means for comparing predetermined multiple count outputs of said feedback counter and command counter includes means for producing a first difference signal when the phase difference between said command counter and said feedback counter exceeds a predetermined value and a second difference signal when the phase difference between said command counter and said feedback counter is less than said second value, said source of machine tool motion command signals includes means for producing motion command signals at a first and a second frequency, said second frequency being lower than said first frequency, and said means responsive to said difference signal for enabling machine tool command signals to be applied from said source to said means for moving said machine tool includes means for applying motion command signals at said first frequency responsive to said first difference signal and for applying motion command signals at said second frequency responsive to said second difference signal.

Claim 8

Dependent Claim 180 words

A system as recited in claim 3 wherein said means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce a difference signal includes: means for generating a first pulse signal having a width determined by the interval between the two last counts of said command and feedback counters; means for generating a second pulse signal simultaneously with the generation of said first pulse signal and having a predetermined fixed width; means for comparing the width of said first and said second pulses for producing a first gate enabling signal when said first pulse width is less than said second pulse width; means for generating third pulse signals having a pulse width determined by the interval between two identical count outputs of said respective feedback and command counters which occur at predetermined locations near the beginning of said respective counters; and first gate means to which said first gate enabling signals and said third pulse signals are applied for producing as its output said difference signal comprising said third pulse train.

Claim 9

Dependent Claim 84 words

A system as recited in claim 5 wherein said means for comparing the outputs of said command and feedback counters to produce a difference signal includes: a second gate means; means for generating a second gate enabling signal during intervals elapsing between successive first gate enabling signals; and third gate means to which said second gate enabling signals and said third pulse signals are applied for producing a train of signals, each representing the distance of said machine tool to the desired end point.

Claim 10

Dependent Claim 137 words

A system as recited in claim 3 wherein said source of motion command signals includes: means for generating a first train of pulses having a feed rate frequency; first gate means; means for generating second pulse signals each having a width representative of the lag between the actual position of said machine tool and the commanded position occurring at the end of a predetermined distance; means for generating third pulse signals each having a width representative of the actual distance of said machine tool from said desired position; means for applying said first train of pulses to said first gate means; and means to which said second and third pulses are applied for enabling said first gate means to pass said first train of pulses until said third pulse signals are narrower than said second pulse signals.

Claim 11

Dependent Claim 97 words

A system as recited in claim 7 wherein said means for generating second pulse signals includes: following error counter means having a count capacity representative of a count required for said machine tool table to move said predetermined distance; means for driving said following error counter responsive to said first train of pulses; and means for comparing the output of the last count of said following error counter and the output of said feedback counter at a count location therein similar to the last count of said following error counter for generating second pulse signals responsive thereto.

Claim 12

Dependent Claim 58 words

Apparatus as recited in claim 8 wherein said means for driving said following error counter responsive to said first train of pulses includes: means for modulating said second train of pulses on oscillations from said source of oscillations, to produce a resultant pulse train; and means for driving said following error counter means with said resultant pulse train.

Claim 13

Independent Claim 312 words

A system for directing a multi-coordinate axis numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising for each axis; feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said command counter into a count state representative of said second position; means for generating a feed rate pulse train; means responsive to said feed rate pulse train and count output from said feedback counter for generating following error pulse signals each representative of the lag between the actual machine tool position and a commanded machine tool position occurring at the end of a predetermined commanded distance of travel; means responsive to the relative phase relationship between said command and feedback counter outputs for generating difference pulse signals each representing the actual distance of said machine tool from its second position; first gate means to which said feed rate pulse train is applied; means to which said following error and difference pulse signals are applied for enabling said first gate means to pass said feed rate pulse train to said means for generating following error pulse signals until each said difference pulse signal has a smaller width than each said following error pulse signal; means for moving said machine tool responsive to said following error pulse signals; means for generating a motion indicating signal responsive to each increment of motion of said machine tool; a source of oscillations; means for driving said command counter responsive to said oscillations; means for modulating said motion indicating signals on said oscillations; and means for driving said feedback counter with said modulated oscillations.

Claim 14

Independent Claim 312 words

A system for directing a multi-coordinate axis numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising for each axis; feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said command counter into a count state representative of said second position; means for generating a feed rate pulse train; means responsive to said feed rate pulse train and count output from said feedback counter for generating following error pulse signals each representative of the lag between the actual machine tool position and a commanded machine tool position occurring at the end of a predetermined commanded distance of travel; means responsive to the relative phase relationship between said command and feedback counter outputs for generating difference pulse signals each representing the actual distance of said machine tool from its second position; first gate means to which said feed rate pulse train is applied; means to which said following error and difference pulse signals are applied for enabling said first gate means to pass said feed rate pulse train to said means for generating following error pulse signals until each said difference pulse signal has a smaller width than each said following error pulse signal; means for moving said machine tool responsive to said following error pulse signals; means for generating a motion indicating signal responsive to each increment of motion of said machine tool; a source of oscillations; means for driving said command counter responsive to said oscillations; means for modulating said motion indicating signals on said oscillations; and means for driving said feedback counter with said modulated oscillations.

Claim 15

Dependent Claim 151 words

A system as recited in claim 10 wherein said means responsive to said feed rate pulse train and an output from said feedback counter for generating following error pulse signals each representative of the lag between the actual machine tool position and a commanded machine tool position includes a second means coupled to the output of said first gate means for modulating said feed rate pulse train on oscillations from said source of oscillations; a following error counter having a count capacity equal to the count output of said feedback counter; means for applying the output of said second means for modulating to said following error counter to drive it through its successive count conditions; and means responsive to the full count output of said following error counter and said count output of said feedback counter for generating a following error pulse having a width equal to the interval occurring therebetween.

Claim 16

Dependent Claim 69 words

A system as recited in claim 10 wherein said means responsive to said command and feedback counter outputs for generating difference pulse signals each represenTing the actual distance of said machine tool from its second position includes means to which said identical count outputs of said command and feedback counters are applied for generating a pulse having a width determined by the interval occurring between said identical count outputs.

Claim 17

Dependent Claim 175 words

A system as recited in claim 10 wherein said means to which said following error and difference pulse signals are applied for enabling said first gate means to pass said feed rate pulses to said means for generating following error pulse signals includes; flip-flop means having a first and second stable state and producing a first gate enabling output when in its first stable state; a second gate means to which said following error and difference pulse signals are applied for producing a first output for driving said flip-flop to its first stable state when each said difference pulse signal has a larger width than each said following error pulse signal and a second output for driving said flip-flop to its second stable state when each said difference pulse signal has a smaller width than each said error pulse signal; means for applying the output of said second gate means to said flip-flop means; and means for applying the output of said flip-flop means when in its first stable state to said first gate means.

Claim 18

Dependent Claim 139 words

A system as recited in claim 10 wherein there is included: means for deriving a low frequency pulse train from said source of oscillations having a frequency that is low compared to the frequency of said feed rate pulse signals; a third gate means to which said low frequency pulse train is applied; means for applying said low frequency pulse train to said third gate means; means for enabling said third gate responsive to said difference pulse signals having a width smaller than a predetermined amount; a fourth gate means; means for applying the output of said first gate means to said fourth gate means; means for applying the output of said third gate means to said fourth gate means; and means coupling the output of said fourth gate means to said means for generating following error pulse signals.

Claim 19

Dependent Claim 155 words

A system as recited in claim 14 wherein said means for enabling said third gate means includes a second flip-flop means having a first and second stable state and providing a third gate enabling output when in its first stable state; a fifth gate means; means for recurrently generating a timing pulse having a predetermined pulse width; means for applying said timing pulse and said difference pulse signals to said fifth gate means to enable said fifth gate means to produce an output to drive said second flip-flop means to its first stable state when each of said timing pulses is smaller in duration than each of said difference pulses, and to drive said second flip-flop means to its second stable state when each of said timing pulses is larger in duration than each of said difference pulses; and means for applying said fifth gate means output to the input of said second flip-flop means.

Claim 20

Independent Claim 328 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising for each axis: feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said command counter into a count state representative of said second position; means for generating a feed rate pulse train; a following error counter having a predetermined count capacity; means responsive to the full count output of said following error counter and the count output of said feedback counter at a count equivalent to said full count output for generAting following error pulses each having a width determined by the difference in the interval occurring between said counts; means for moving said machine tool responsive to said following error pulses; means for generating a motion indicating signal responsive to each increment of motion of said machine tool; a source of oscillations; means for driving said command counter responsive to said oscillations; means for modulating said motion indicating signals on said oscillations; means for driving said feedback counter responsive to said oscillations modulated by said motion indicating signals; means for modulating said oscillations with said feed rate pulse train; means for driving said following error counter with said oscillations modulated by said feed rate pulse train; means responsive to multiple outputs of said command and feedback counter outputs for generating difference pulse signals, each representing the actual distance of said machine tool from the second position; and means responsive to said difference pulse signals being smaller than a predetermined width for terminating further application of said oscillations modulated by said feed rate pulse train to said following error counter to thereby terminate further motion of said machine tool.

Claim 21

Independent Claim 328 words

A system for directing a numerically controlled machine tool to move from a first position to a second position in response to a numerical word representing said second position, and wherein each position along each coordinate axis is specified by a numerical word, said system comprising for each axis: feedback counter means for providing an output representative of the first position of said machine tool; command counter means; means responsive to a numerical word representative of a second position for placing said command counter into a count state representative of said second position; means for generating a feed rate pulse train; a following error counter having a predetermined count capacity; means responsive to the full count output of said following error counter and the count output of said feedback counter at a count equivalent to said full count output for generAting following error pulses each having a width determined by the difference in the interval occurring between said counts; means for moving said machine tool responsive to said following error pulses; means for generating a motion indicating signal responsive to each increment of motion of said machine tool; a source of oscillations; means for driving said command counter responsive to said oscillations; means for modulating said motion indicating signals on said oscillations; means for driving said feedback counter responsive to said oscillations modulated by said motion indicating signals; means for modulating said oscillations with said feed rate pulse train; means for driving said following error counter with said oscillations modulated by said feed rate pulse train; means responsive to multiple outputs of said command and feedback counter outputs for generating difference pulse signals, each representing the actual distance of said machine tool from the second position; and means responsive to said difference pulse signals being smaller than a predetermined width for terminating further application of said oscillations modulated by said feed rate pulse train to said following error counter to thereby terminate further motion of said machine tool.

Claim 22

Independent Claim 341 words

A system for directing a multiaxial numerically controlled machine tool table to move from its present or first location to a second location, wherein each location of the machine tool table along each coordinate axis may be specified by a numerical word comprising for each axis: feedback counter means; command counter means; a source of numerical words each representative of a desired location for said machine tool; means for reading out one of the numerical words of said source; means responsive to the numerical words read out for altering the count in said command counter to be representative of a desired position for said machine tool table; a reference source of oscillation; means for applying the output of said reference source of oscillation to said command counter to advance its count responsive thereto; means responsive to oscillations from said source and to said machine tool table motion for altering the count in said feedback counter means for always maintaining the count of said feedback counter means representative of the location of said machine tool table; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce a first difference signal when the difference between said count outputs exceeds a predetermined minimum value and a second difference signal representative of the actual interval between said count outputs when the difference between said count outputs is less than said minimum value; means responsive to said first difference signal for moving said machine tool table towards said second position at first velocity and responsive to said second difference signal for moving said machine tool table toward said second position at a second velocity lower than said first velocity; means responsive to said second difference signal attaining a predetermined minimum value for terminating the motion of said machine tool table; and means responsive to the termination of the motion of said machine tool table along all said axes for actuating said means for reading out to read out another of said numerical words from said source.

Claim 23

Independent Claim 341 words

A system for directing a multiaxial numerically controlled machine tool table to move from its present or first location to a second location, wherein each location of the machine tool table along each coordinate axis may be specified by a numerical word comprising for each axis: feedback counter means; command counter means; a source of numerical words each representative of a desired location for said machine tool; means for reading out one of the numerical words of said source; means responsive to the numerical words read out for altering the count in said command counter to be representative of a desired position for said machine tool table; a reference source of oscillation; means for applying the output of said reference source of oscillation to said command counter to advance its count responsive thereto; means responsive to oscillations from said source and to said machine tool table motion for altering the count in said feedback counter means for always maintaining the count of said feedback counter means representative of the location of said machine tool table; means for comparing the relative phase relationship between predetermined multiple count outputs of said command and feedback counters to produce a first difference signal when the difference between said count outputs exceeds a predetermined minimum value and a second difference signal representative of the actual interval between said count outputs when the difference between said count outputs is less than said minimum value; means responsive to said first difference signal for moving said machine tool table towards said second position at first velocity and responsive to said second difference signal for moving said machine tool table toward said second position at a second velocity lower than said first velocity; means responsive to said second difference signal attaining a predetermined minimum value for terminating the motion of said machine tool table; and means responsive to the termination of the motion of said machine tool table along all said axes for actuating said means for reading out to read out another of said numerical words from said source.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1975-06-06	1975-12-06	1976-06-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1979-06-06	1979-12-06	1980-06-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1983-06-06	1983-12-06	1984-06-06	$7700.00	Window Closed / Lapsed

Numerical servo motor control system

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