Automatic acceleration/deceleration for a numerical controlled machine tool

Claim 2

In a numerically controlled machine tool system of the type having a feedrate generator for generating a feedrate pulse wavetrain which is applied to drive an iteration counter which in response thereto provides a count to indicate elapsed time by its reciprocal count indicates time remaining to complete a commanded motion, and having rate multipliers for each axis for generating axis motion command pulse trains when driven by said feedrate pulse wavetrain, means for accelerating said machine tool to a predetermined desired maximum velocity with a constant acceleration and for decelerating said machine tool from said maximum velocity down to zero with a constant deceleration comprising: velocity counter means to which said feedrate pulse wavetrain is applied for converting an axis motion command pulse train into a count representing the frequency of said command pulse train divided by a constant, means for comparing the count in said iteration counter and the count in said velocity counter for producing an output indicative thereby, and control means responsive to the output of said means for comparing for controlling the frequency of the federate pulse wavetrain generated by said feedrate generator.

Claim 3

The invention in accordance with claim 1, wherein said control means operates to increase the frequency of the feedrate pulse wavetrain when the count of said iterative counter equals or exceeds the count of said velocity counter means, and operates to decrease the frequency of the feedrate pulse wavetrain when the count of the iteration counter is less tHan the count of said velocity counter means.

Claim 4

The invention in accordance with claim 1 wherein there is also included: means for determining when said iteration counter has counted to a predetermined count and in response thereto causing the complement of the count of said iteration counter to be applied to said means for comparing instead of the actual count.

Claim 5

The invention in accordance with claim 2, wherein said numerically controlled machine tool system has a circular interpolation capability and also includes: an end point down counter for each axis having a count therein indicative of the distance required to be moved by said machine tool to the end of a circular motion, means for applying the respective axis command pulse trains to each end point counter to cause it to count downward, means for generating a circular signal indicative of a circular interpolation being performed by said numerically controlled machine tool, means responsive to said circular signal for periodically applying to said means for comparing an end point down counter count instead of an iterative counter count, means responsive to the output of said means for comparing indicating the velocity counter count exceeds the end point counter count for thereafter applying to said means for comparing only the end point down counter count.

Claim 6

The invention in accordance with claim 1, wherein said means for determining the frequency of the feedrate generator pulse wavetrain generated by said feedrate generator includes a voltage controlled oscillator having its output connected to drive said feedrate generator, and wherein said system additionally includes: a capacitor connected to control said voltage controlled oscillator with the voltage thereacross, a constant current charging voltage source, a constant current discharging voltage source, and means for charging said capacitor with a voltage from said charging voltage source or discharging a voltage from said capacitor into said discharging voltage source responsive to the output of said means for comparing.

Claim 7

In a numerically controlled machine tool system of the type wherein a feedrate generator generates a feedrate pulse wavetrain which is applied to an iteration counter for measuring the number of iterations being performed by axis digital differential integrators to which the feedrate pulse wavetrain is also applied for generating and axis motion command pulse wavetrain, and improved acceleration and deceleration control system comprising means for periodically converting an axis motion command pulse wavetrain into a width-modulated pulse having its width proportional to the frequency of said motion command pulse train and inversely proportional to the acceleration or deceleration desired comprising: a velocity counter, means for applying said feedrate pulse wavetrain to said velocity counter, means for applying said width-modulated pulse to said velocity counter for enabling said velocity counter to count only over an interval measured by the width of said pulse, means for scaling the count in said velocity counter to the count in said iteration counter, means for comparing the iteration counter count with the scaled velocity counter count and providing an output indicative of equality of counts or of which count is larger, means for determining the frequency of the feedrate generator pulse wavetrain generated by the feedrate generator, means responsive to said means for comparing output indicating that the iteration counter count is equal to or larger than said scaled count of said velocity counter for controlling said means for determining to increase towards a predetermined maximum the frequency of the feedrate generator pulse wavetrain, means responsive to said means for comparing output indicating that the iteration counter count is less than said velocity counter count for reducing towards a predetermined minimum the frequeNcy of said feedrate generator pulse wavetrain.

Claim 8

In a numerically controlled machine tool system of the type wherein a feedrate generator generates a feedrate pulse wavetrain which is applied to an iteration counter for measuring the number of iterations being performed by axis digital differential integrators to which the feedrate pulse wavetrain is also applied for generating and axis motion command pulse wavetrain, and improved acceleration and deceleration control system comprising means for periodically converting an axis motion command pulse wavetrain into a width-modulated pulse having its width proportional to the frequency of said motion command pulse train and inversely proportional to the acceleration or deceleration desired comprising: a velocity counter, means for applying said feedrate pulse wavetrain to said velocity counter, means for applying said width-modulated pulse to said velocity counter for enabling said velocity counter to count only over an interval measured by the width of said pulse, means for scaling the count in said velocity counter to the count in said iteration counter, means for comparing the iteration counter count with the scaled velocity counter count and providing an output indicative of equality of counts or of which count is larger, means for determining the frequency of the feedrate generator pulse wavetrain generated by the feedrate generator, means responsive to said means for comparing output indicating that the iteration counter count is equal to or larger than said scaled count of said velocity counter for controlling said means for determining to increase towards a predetermined maximum the frequency of the feedrate generator pulse wavetrain, means responsive to said means for comparing output indicating that the iteration counter count is less than said velocity counter count for reducing towards a predetermined minimum the frequeNcy of said feedrate generator pulse wavetrain.

Claim 9

The invention in accordance with claim 6, wherein there is also included: means for determining when said iteration counter has counted to a predetermined count and in response thereto causing the complement of the count of said iteration counter to be applied to said means for comparing instead of the actual count.

Claim 10

The invention in accordance with claim 7, wherein said numerically controlled machine tool system has a circular interpolation capability and also includes: an end point down counter for each axis having a count therein indicative of the distance required to be moved by said machine tool to the end of a circulate motion, means for applying the respective axis command pulse trains to each end point counter to cause it to count downward, means for generating a circular signal indicative of a circular interpolation being performed by said numerically controlled machine tool, means responsive to said circular signal for periodically applying to said means for comparing and end point down counter count instead of an iteration counter count, means responsive to the output of said means for comparing indicating that the velocity counter count exceeds the end point counter count for thereafter applying to said means for comparing only the end point down counter count.

Claim 11

IN a numerically controlled machine toll system of the type having a plurality of axes, a feedrate generator for generating a feedrate pulse wavetrain which is applied to a digital differential integrator for each axis for generating a command pulse wavetrain for each axis, and an iteration counter which receives feedrate pulses for counting the number of iterations being performed by the axis digital differential integrators, means for increasing the velocity of said machine tool up to a desired maximum velocity at a constant rate of acceleration and for decelerating from said maximum velocity to zero velocity at a constant rate of deceleration comprising: a means for each axis to which a command pulse wavetrain is applied for producing an analog signal having an amplitude representative of the frequency of said command pulse wavetrain, means for converting an analog signal into a pulse having a width representative of the amplitude thereof, first counter means for successively enabling the analog signal of each axis to be applied to said means for converting, a velocity counter, means for applying feedrate generator pulses to said velocity counter, means for applying pulses to said velocity counter from said means for converting to enable said velocity counter to count only during the interval of one of said pulses, means synchronized by said first counter means for scaling up the count in said velocity counter for each axis, means for comparing the scaled up count in said velocity counter for each axis with the count in said iteration counter and producing for each axis an acceleration signal whenever said iteration count equals or exceeds said velocity counter count, means for each axis for storing said acceleration signal and means for detecting when all of said means for storing contains acceleration signals for increasing the frequency of the feedrate generator wavetrain and for detecting when less than all of said means for storing contains acceleration signals for decreasing the frequency of the feedrate generator wavetrain.

Claim 12

IN a numerically controlled machine toll system of the type having a plurality of axes, a feedrate generator for generating a feedrate pulse wavetrain which is applied to a digital differential integrator for each axis for generating a command pulse wavetrain for each axis, and an iteration counter which receives feedrate pulses for counting the number of iterations being performed by the axis digital differential integrators, means for increasing the velocity of said machine tool up to a desired maximum velocity at a constant rate of acceleration and for decelerating from said maximum velocity to zero velocity at a constant rate of deceleration comprising: a means for each axis to which a command pulse wavetrain is applied for producing an analog signal having an amplitude representative of the frequency of said command pulse wavetrain, means for converting an analog signal into a pulse having a width representative of the amplitude thereof, first counter means for successively enabling the analog signal of each axis to be applied to said means for converting, a velocity counter, means for applying feedrate generator pulses to said velocity counter, means for applying pulses to said velocity counter from said means for converting to enable said velocity counter to count only during the interval of one of said pulses, means synchronized by said first counter means for scaling up the count in said velocity counter for each axis, means for comparing the scaled up count in said velocity counter for each axis with the count in said iteration counter and producing for each axis an acceleration signal whenever said iteration count equals or exceeds said velocity counter count, means for each axis for storing said acceleration signal and means for detecting when all of said means for storing contains acceleration signals for increasing the frequency of the feedrate generator wavetrain and for detecting when less than all of said means for storing contains acceleration signals for decreasing the frequency of the feedrate generator wavetrain.

Claim 13

The invention in accordance with claim 9, wherein said numerically controlled machine tool system has a circular interpolation capability and also includes: and end point down counter for each axis having a count therein indicative of the distance required to be moved by said machine tool for circular interpolation, means for applying the respective axis command pulse trains to each end point counter to cause it to count downward, means for generating a circular signal indicative of a circular intErpolation being performed by said numerically controlled machine tool, means responsive to said circular signal for establishing alternate intervals during which said end point counter counts are applied synchronized by said first counter to said means for comparing in place of said iteration counter counts, and means responsive to said means for detecting during an interval of comparing end point counter counts when less than all of said means for storing contains an acceleration signal for thereafter applying to said means for comparing only said end point counter counts.

Claim 14

The invention in accordance with claim 10, wherein there is also included: means for detecting when said iteration counter has counted to a predetermined count, and in response thereto causing the complement of the count of said iteration counter to be applied to said means for comparing instead of the actual count.

Claim 15

The invention in accordance with claim 9, wherein said means for detecting when all of said means for storing contains an acceleration signal for increasing the frequency of the feedrate generator wavetrain for detecting when less than all of said means contains an acceleration signal for decreasing the frequency of the feedrate generator wavetrain, includes: a voltage controlled oscillator connected to drive said feedrate generator, a capacitor connected to control said voltage controlled oscillator with the voltage thereacross, a charging voltage source, a discharging voltage source, means for charging up said capacitor form said charging voltage source responsive to said means for indicating that all of said means for storing contains an acceleration signal, and means for discharging said capacitor from said discharging voltage source responsive to said means foe detecting indicating that not all of said means for storing contains an acceleration signal.

Claim 16

The invention in accordance with claim 9, wherein there is included manually operable means, and wherein said charging voltage source and said discharging voltage source include means for enabling the application of charging voltage and discharging voltage to said capacitor responsive to operation of said manually operable means.