Automatic drafting control

Claim 2

In a drafting machine, the combination comprising a. a drafting head, b. drive means including a servomotor having an output element connected to drive said head relatively over a drafting surface, c. director means to receive directing digital information and to operate thereon to provide a series of directing pulses corresponding to the coordinates of desired positions of the head relative to the drafting surface, d. a counter having digital output, e. a digital to analog converter connected to be responsive to counter digital output to produce an analog signal corresponding to the count in the counter, said motor being connected to be responsive to a directing version of said analog signal, f. feedback means responsive to the degree of movement of said element to produce a corresponding series of feedback pulses, and g. control apparatus including clock means connected to be responsive to said directing and feedback pulses to change the count in the counter so as to control the drive of the head to said desired position, h. said control apparatus including logic means responsive to reception of timewise nearly coincident directing and feedback pulses to provide an output discriminating said nearly coincident pulses and operable to control passage of clock pulses to said counter.

Claim 3

The combination of claim 1 wherein said logic means comprises time aperture defining means operable to define a time aperture characterized as longer than the sum of the durations of at least one clock pulse but less than the average interval between successive directing and feedback pulses, sensing means connected to sense the arrival within said time aperture of both directing and feedback pulses and their sign, bistable means characterized as controllably settable in response to said pulse arrival, and means to control clock pulse delivery to the counter in accordance with the settings of said bistable means.

Claim 4

The combination of claim 2 wherein said logic means includes flip-flops connected to be set in response to arrival of said nearly concurrent pulses within a predetermined time inteRval of less duration than the normal interval between successive directing pulses, and gates responsive to the settings of said flip-flops to control clock pulse delivery to the counter.

Claim 5

The combination of claim 1 wherein said drive means includes a driving amplifier having two inputs one to receive said converter analog signal to produce said directing version of the analog signal, and a generator responsive to rotation of said servomotor output element to produce a feedback analog signal applied to the other input of the driving amplifier.

Claim 6

In a drafting machine, the combination comprising a. a drafting head, b. drive means including a first servomotor having a first output element connected to drive said head relatively over said drafting surface in a first direction, and a second servomotor having a second output element connected to drive said head relatively over said drafting surface in a second direction, c. director means to receive directing digital information and to operate thereon to provide first and second directional coordinates of desired positions of the head relative to said drafting surface, d. first and second digital counters having digital output, e. first and second digital to analog converters connected to be responsive to first and second counter digital outputs respectively thereby to produce first and second analog signals corresponding to the counts in the first and second counters respectively, said first and second motors being connected to be responsive to directing versions of said first and second analog signals respectively, f. first and second feedback means responsive to the degree of movement of said first and second elements respectively to produce corresponding first and second series of feedback pulses, and g. control apparatus including clock means connected to be responsive to said first and second series of directing and feedback pulses to change the counts in said first and second counters so as to control the drive of said head incrementally in said directions to said desired positions, h. said control apparatus including logic means responsive to reception of timewise nearly coincident directing and feedback pulses to provide output discriminating said nearly coincident pulses and operable to control passage of clock pulses to said counters.

Claim 7

In a drafting machine, the combination comprising a. a drafting head, b. drive means including a first servomotor having a first output element connected to drive said head relatively over said drafting surface in a first direction, and a second servomotor having a second output element connected to drive said head relatively over said drafting surface in a second direction, c. director means to receive directing digital information and to operate thereon to provide first and second directional coordinates of desired positions of the head relative to said drafting surface, d. first and second digital counters having digital output, e. first and second digital to analog converters connected to be responsive to first and second counter digital outputs respectively thereby to produce first and second analog signals corresponding to the counts in the first and second counters respectively, said first and second motors being connected to be responsive to directing versions of said first and second analog signals respectively, f. first and second feedback means responsive to the degree of movement of said first and second elements respectively to produce corresponding first and second series of feedback pulses, and g. control apparatus including clock means connected to be responsive to said first and second series of directing and feedback pulses to change the counts in said first and second counters so as to control the drive of said head incrementally in said directions to said desired positions, h. said control apparatus including logic means responsive to reception of timewise nearly coincident directing and feedback pulses to provide output discriminating said nearly coincident pulses and operable to control passage of clock pulses to said counters.

Claim 8

The combination of claim 5 wherein said machine includes a table in the form of a block, and said servomotors are mounted on said block.

Claim 9

The combination of claim 6 wherein said first and second output elements comprise elongated lead screws extending in said first and second directions, respectively, there being a carriage displaced in said first direction in response to rotation of the first lead screw, and said second servomotor being carried by said carriage.

Claim 10

In a drafting machine, the combination comprising: a. a drafting head, b. drive means including a motor having an output element connected to drive the head relatively over a drafting surface, c) director means to receive directing digital information and to operate thereon to provide a series of directing pulses corresponding to the coordinates of desired positions of the head relative to the drafting surface, d) a counter having digital output, e) means connected to be responsive to counter digital output for controlling the motor, f) feedback means responsive to the degree of movement of said element to produce a corresponding series of feedback pulses, and g) control apparatus connected to be responsive to said directing and feedback pulses to change the count in the counter so as to control the drive of the head to said desired position, h) said control apparatus including logic means responsive to timewise nearly coincident directing and feedback pulses to provide an output discriminating said nearly coincident pulses and operable to control passage of pulses to the counter.

Claim 11

In a drafting machine, the combination comprising: a. a drafting head, b. drive means including a motor having an output element connected to drive the head relatively over a drafting surface, c) director means to receive directing digital information and to operate thereon to provide a series of directing pulses corresponding to the coordinates of desired positions of the head relative to the drafting surface, d) a counter having digital output, e) means connected to be responsive to counter digital output for controlling the motor, f) feedback means responsive to the degree of movement of said element to produce a corresponding series of feedback pulses, and g) control apparatus connected to be responsive to said directing and feedback pulses to change the count in the counter so as to control the drive of the head to said desired position, h) said control apparatus including logic means responsive to timewise nearly coincident directing and feedback pulses to provide an output discriminating said nearly coincident pulses and operable to control passage of pulses to the counter.