All digital sampling servo system

Claim 2

A numerical control system for commanding slide motion along each axis of a machine tool comprising, for each axis, means for generating successive aBsolute location number signals representative of successive locations to which the slide for an axis must move within successive, identical, predetermined intervals, means for generating successive reference time signals spaced apart by said identical predetermined intervals, means responsive to successive absolute location number signals and successive reference time signals for generating successive command signals wherein each command signal is phase delayed from a reference time signal by an amount representative of a location number value, means for generating a slide signal having a phase delayed from said reference by an amount representative of the distance of said slide from a reference location, a phase detector, means for successively applying said command signals and said slide signals to said phase detector to produce an output signal having a phase representative of a phase difference of its inputs, and means responsive to the output of said phase detector for moving said slide in a direction to minimize said phase difference.

Claim 3

A numerical control system as recited in claim 1, wherein said means for generating successive location number signals representative of successive locations to which the slide for an axis must move within successive identical predetermined intervals, includes a source of said location numbers, a register means, means for generating a demand signal at the end of each of said predetermined intervals, and means for transferring a location number from said source to said register means responsive to a demand signal.

Claim 4

A numerical control signal as recited in claim 2, wherein said means for generating command signals includes flip flop means having set and reset states, means for driving said flip flop means to its set state responsive to each reference time signal, means responsive to the location number in said register means and to the output of said flop flop means when in its set state to generate a reset pulse at an interval after said first pulse determined by a location number value, means for driving said flip flop means to its reset state responsive to a reset pulse, and means responsive to each set output of said flop flop means for generating a command signal having a width determined by the interval between set outputs.

Claim 5

A numerical control system as recited in claim 3, wherein said means responsive to the location number in said register and to the output of said flip flop means when in its set state to generate a second pulse at an interval after said first pulse determined by said location number value includes a counter means, means responsive to a demand signal for transferring the location number in said register means into said counter means, a source of clock pulses, and gate means responsive to the set output of said flip flop means for enabling said counter means to count responsive to clock pulse from said source, and to generate a second signal when it has counted through said location number.

Claim 6

In a numerical control system in which data is supplied for commanding slide motion along each one of the axes of a machine tool in the form of successive absolute location numbers which define successive loci along a path which must be reached by all axes within simultaneously generated successive equal predetermined intervals comprising, for each axis of said numerical control system, a phase detector, means to generate slide position square wave signals, each having a phase displaced from a reference representative of the location of the machine tool slide with respect to a reference location, means to apply slide square wave signals to said phase detector, means responsive to said absolute location numbers to generate command square wave signals, each command square wave signal having a phase displaced from said reference by an amount representative of the value of said absolute locaTion number, means for applying said command square wave signals to said phase detector to enable said phase detector to detect the difference in phase between each said command and said slide position signals, means responsive to the phase difference detected by the phase detector for each axis to move the respective slide for each axis to minimize said phase difference, and means operative at the end of said predetermined interval to replace said first of said location numbers with the next one of said location numbers.

Claim 7

In a numerical control system in which data is supplied for commanding slide motion along each one of the axes of a machine tool in the form of successive absolute location numbers which define successive loci along a path which must be reached by all axes within simultaneously generated successive equal predetermined intervals comprising, for each axis of said numerical control system, a phase detector, means to generate slide position square wave signals, each having a phase displaced from a reference representative of the location of the machine tool slide with respect to a reference location, means to apply slide square wave signals to said phase detector, means responsive to said absolute location numbers to generate command square wave signals, each command square wave signal having a phase displaced from said reference by an amount representative of the value of said absolute locaTion number, means for applying said command square wave signals to said phase detector to enable said phase detector to detect the difference in phase between each said command and said slide position signals, means responsive to the phase difference detected by the phase detector for each axis to move the respective slide for each axis to minimize said phase difference, and means operative at the end of said predetermined interval to replace said first of said location numbers with the next one of said location numbers.

Claim 8

In a system as recited in claim 5 wherein said means for generating command square wave signals each having a phase displaced from a reference comprises flip flop means having set and reset states, means for generating a first pulse at each reference phase time, means for applying said first pulse at each reference phase time to said flip flop means to drive said flip flop means to its set state in response to each of said pulses, means responsive to a location number to generate a second pulse at a time spaced from said reference phase time by an interval having a duration representative of the location number value, means for resetting said flop flop means responsive to said second pulse, means for deriving from the said output of said flip flop means a third pulse signal occurring at the trailing edge of the said output of said flip flop means, binary counter means, and means for driving said binary counter means responsive to said trailing edge pulse output of said means whereby the output of said binary counter means constitutes command pulse outputs.

Claim 9

In a system as recited in claim 6 wherein said means for generating a first pulse at each reference phase time includes a source of clock pulses, reference counter means to which clock pulses from said source are applied for producing reference pulses in response thereto, differentiating circuit means to which said reference pulses are applied, means for deriving from said differentiating circuit a first pulse in response to the leading and trailing edge of a reference pulse applied to said differentiating circuit.

Claim 10

In a system as recited in claim 7 wherein said means responsive to a location number to generate a second pulse at a time spaced from said reference pulse time by an interval having a duration representative of the location number, includes counter means, means to cause said counter to assume a count state representative of said location number, means responsive to said flip flop means being driven to its set state to apply clock pulses from said source to said preset counter means to cause said counter to count and provide a second pulse output when it has counted through said location number, and means responsive to the output of said flip flop means when it is reset to terminate further application of clock pulses to said preset counter means.

Claim 11

In a numerical control system for a machine tool, the improvement comprising, means for each axis, for generating successively absolute location numbers which define successive loci along a path which must be reached by a slide within successive equal predetermined intervals, a preset counter means for each axis, means for each axis for entering absolute location numbers successively into the respective preset counter means for each axis at the end of each predetermined interval, a source of clock pulses for all axes, means for all axes for converting clock pulses from said source into a reference square wave signal train, flip flop means for each axis having a set and reset state, means for driving the flip flop means for each axis to its set state in response to the leading and trailing edge of each square wave in said reference pulse train, means for each axis responsive to the output of said flip flop means when in its set state for enabling the respective preset counter means fOr each axis to be driven responsive to clock pulses from said clock pulse source, means responsive to the preset counter means for each axis being driven to a count state indicative of having counted through the value of a location number to reset said respective flip flop means for each axis, a binary counter means for each axis, means for deriving from the flip flop means of each axis a signal having a duration representative of the interval during which the respective flip flop means is maintained in its set state, and means for driving the binary counter means for each axis in response to the trailing edge of the respective signals representative of the respective intervals over which the flip flop means for each axis is in its set state to produce a command square wave signal for each axis having a phase delayed from a reference phase in an amount representative of the location number for each axis.

Claim 12

In a numerical control system for a machine tool, the improvement comprising, means for each axis, for generating successively absolute location numbers which define successive loci along a path which must be reached by a slide within successive equal predetermined intervals, a preset counter means for each axis, means for each axis for entering absolute location numbers successively into the respective preset counter means for each axis at the end of each predetermined interval, a source of clock pulses for all axes, means for all axes for converting clock pulses from said source into a reference square wave signal train, flip flop means for each axis having a set and reset state, means for driving the flip flop means for each axis to its set state in response to the leading and trailing edge of each square wave in said reference pulse train, means for each axis responsive to the output of said flip flop means when in its set state for enabling the respective preset counter means fOr each axis to be driven responsive to clock pulses from said clock pulse source, means responsive to the preset counter means for each axis being driven to a count state indicative of having counted through the value of a location number to reset said respective flip flop means for each axis, a binary counter means for each axis, means for deriving from the flip flop means of each axis a signal having a duration representative of the interval during which the respective flip flop means is maintained in its set state, and means for driving the binary counter means for each axis in response to the trailing edge of the respective signals representative of the respective intervals over which the flip flop means for each axis is in its set state to produce a command square wave signal for each axis having a phase delayed from a reference phase in an amount representative of the location number for each axis.