Control system for producing multi-axis contour movement for a stepping motor drive

Claim 1

In a system capable of moving one part relative to another by relative movement of at least three series connected relatively movable members along at least two predetermined axes defined by cooperating structure of adjacent members and having at least two step motors each acting between and moving said adjacent members along the predetermined axes in discrete increments and acting together to drive said parts along a series of successive segments approximating a predetermined path, the improvement comprising clock pulse generator means for generating a train of clock pulses; logic means to select as a major axis that one of the axes having the greater number of steps to be taken over at least the segment next to be followed; interpolation pulse generator means for generating a major axis interpolation pulse for each clock pulse and minor axis interpolation pulses as required by the logic of the system to follow the segment, said interpolation logic employing means whereby minor axis interpolation pulses are derived only after each major axis pulse upon immediate evaluation of whether an interpolation pulse is required along each minor axis and before the next clock pulse; and means for deriving step motor pulses to drive their respective step motors from said interpolation pulses for the respective axes.

Claim 8

The method of simulating the following of a straight line segment by interpolation increments along predetermined major and minor axes where remaining steps to be taken along said axes are stored in major and minor axis registers and certain output logic originating from said registers is stored in an accumulator register comprising, setting the major axis register at the number of interpolation steps of which will be required by major axis motion, setting the minor axis register at the number of units of interpolation steps which will be required by minor axis motion, setting an accumulator register at zero, using each pulse from a variable frequency clock to generate successive timing pulses which represent first and second successive time intervals in which successive steps in calculation may occur, making a first arithmetic calculation in the period of the first timing pulse during which the major axis register is always decremented and a single interpolation pulse is output to the major axis step motor logic and the contents of the minor axis register is added in the accumulator register to the contents of accumulator, during the second calculation period testing the output of the accumulator register to sense positive number storage capacity of the register to determine whether its contents contain a positive number and if it does not, during the second calculation passing no signal to the minor axis step motor logic, but if the accumulator 102 does contain a positive number, passing a signal to cause the minor axis register to be decremented and causing one unit output to the minor axis step motor logic 115.

Claim 9

The method of simulating the following of a straight line segment by interpolation increments along predetermined major and minor axes where remaining steps to be taken along said axes are stored in major and minor axis registers and certain output logic originating from said registers is stored in an accumulator register comprising, setting the major axis register at the number of interpolation steps of which will be required by major axis motion, setting the minor axis register at the number of units of interpolation steps which will be required by minor axis motion, setting an accumulator register at zero, using each pulse from a variable frequency clock to generate successive timing pulses which represent first and second successive time intervals in which successive steps in calculation may occur, making a first arithmetic calculation in the period of the first timing pulse during which the major axis register is always decremented and a single interpolation pulse is output to the major axis step motor logic and the contents of the minor axis register is added in the accumulator register to the contents of accumulator, during the second calculation period testing the output of the accumulator register to sense positive number storage capacity of the register to determine whether its contents contain a positive number and if it does not, during the second calculation passing no signal to the minor axis step motor logic, but if the accumulator 102 does contain a positive number, passing a signal to cause the minor axis register to be decremented and causing one unit output to the minor axis step motor logic 115.

Claim 10

The method of simulating the following of a circular arc segment by interpolation increments along predetermined major and minor axes X and Y where remaining steps to be taken along said axes are stored in Delta X and Delta Y registers, the rectangular coordinate position at any given time with respect to a predetermined origin representing the center of the arc are stored in I and J registers corresponding to the X and Y coordinating from said registers is stored in an accumulator register by directly interpolation pulses into X and Y step motor logic, respectively, comprising setting the I register at the value of the X coordinate distance from the circular origin to the start point measured along the X axis, setting the J register at the value of the Y coordinate distance from the same circular origin to the same start point measured along the Y axis, setting the Delta X register at the number of units of X axis motion required to reach the end point of the arc segment, setting Delta Y register 212 at the number of units of Y axis motion required to reach said end point, setting the accumulator at zero, generating a train of variable frequency clock pulses, determining if either Delta X or Delta Y equals zero and, if so directing clock pulse directly into the other axis step logic input. If neither Delta X or Delta Y equals zero enabling clock pulses to enter the interpolation registers, previous to the first calculation, determining the major axis by comparison if I is greater than J or J is greater than I, establishing a first calculation period during which, if I is greater than J: (1) the accumulator is augmented by the contents of the J register (2) a Y axis step is commanded through Y axis step logic input, (3) the Delta Y register is decremented by one and (4) the J register is decremented by one, but if J is greater than I: (1) the accumulator is decremented by the contents of the I register and (2) X axis step is commanded through X axis step logic input (3) the Delta X register is decremented by one and (4) the I register 209 is augmented by one, Sensing the storage condition of the accumulator register at the conclusion of the calculation to determine whether its contents contain a positive or a negative number, and during a second calculation period if J is greater than I, and the accumulator register is not negative taking no action if I is greater than J, and the accumulator register is not positive, taking no action if J is greater than I and the accumulator is negative: (1) the accumulator 208 is augmented by the contents of the J register (2) a Y axis step is commanded through Y axis step logic (3) the Delta Y register is decremented by one, and (4) the J register 210 is decremented by one. If I is greater than J and the accumulator is positive, (1) the accumulator is decremented by the contents of the I register, (2) an X axis step is commanded through X axis step logic (3) Delta X register 211 is decremented by one, and, (4) the I register 209 is augmented by one, and continuing calculations until the contents of both the Delta X and the Delta Y registers equal zero.

Claim 11

The method of simulating the following of a circular arc segment by interpolation increments along predetermined major and minor axes X and Y where remaining steps to be taken along said axes are stored in Delta X and Delta Y registers, the rectangular coordinate position at any given time with respect to a predetermined origin representing the center of the arc are stored in I and J registers corresponding to the X and Y coordinating from said registers is stored in an accumulator register by directly interpolation pulses into X and Y step motor logic, respectively, comprising setting the I register at the value of the X coordinate distance from the circular origin to the start point measured along the X axis, setting the J register at the value of the Y coordinate distance from the same circular origin to the same start point measured along the Y axis, setting the Delta X register at the number of units of X axis motion required to reach the end point of the arc segment, setting Delta Y register 212 at the number of units of Y axis motion required to reach said end point, setting the accumulator at zero, generating a train of variable frequency clock pulses, determining if either Delta X or Delta Y equals zero and, if so directing clock pulse directly into the other axis step logic input. If neither Delta X or Delta Y equals zero enabling clock pulses to enter the interpolation registers, previous to the first calculation, determining the major axis by comparison if I is greater than J or J is greater than I, establishing a first calculation period during which, if I is greater than J: (1) the accumulator is augmented by the contents of the J register (2) a Y axis step is commanded through Y axis step logic input, (3) the Delta Y register is decremented by one and (4) the J register is decremented by one, but if J is greater than I: (1) the accumulator is decremented by the contents of the I register and (2) X axis step is commanded through X axis step logic input (3) the Delta X register is decremented by one and (4) the I register 209 is augmented by one, Sensing the storage condition of the accumulator register at the conclusion of the calculation to determine whether its contents contain a positive or a negative number, and during a second calculation period if J is greater than I, and the accumulator register is not negative taking no action if I is greater than J, and the accumulator register is not positive, taking no action if J is greater than I and the accumulator is negative: (1) the accumulator 208 is augmented by the contents of the J register (2) a Y axis step is commanded through Y axis step logic (3) the Delta Y register is decremented by one, and (4) the J register 210 is decremented by one. If I is greater than J and the accumulator is positive, (1) the accumulator is decremented by the contents of the I register, (2) an X axis step is commanded through X axis step logic (3) Delta X register 211 is decremented by one, and, (4) the I register 209 is augmented by one, and continuing calculations until the contents of both the Delta X and the Delta Y registers equal zero.