GB1203774A - Electrical control system - Google Patents

Abstract

1,203,774. Programmed control of machine tools. HUGHES AIRCRAFT CO. Oct.31, 1967 [Nov.29, 1966], No.49469/67. Heading G3N. The data indicative of the present desired position of a movable element is stored in a position register and is changed by pulses from a movement-sensing transducer, the contents of an overshoot register, containing data indicative of movement of the element past a preceding desired position, being algebraically summed with the contents of the position register before movement of the element to the present desired position is completed. As shown, information input equipment 10, responsive to a photo-electrically read punched tape, reads out serially presented signal groups which are distributed by controls 12 through a logic 18 to a position count register 16. At a predetermined count in the register 16 a feed axis drive 20 is enabled by more signals Mn or Mp from control 12. A feed axis 22 movement occurs together with a movement of a coupled machine element, not shown, which is detected by a transducer 24. The output of the transducer is coupled to a generator 26 producing pulses P, N enabling logic 25 deriving count pulses P<SP>1</SP> N<SP>1</SP> which, through count gates 30 cause counting of the register 16 towards the zero count condition. At zero count logic 28 is enabled and a signal PZ takes up a level disabling the position of control 12 producing signals Mn, Mp whereby drive 20 ceases operation. A zero logic 34 is also coupled to enable gates 30 so that an overshoot register accept pulses P<SP>1</SP>, N<SP>1</SP> from logic 25. Upon starting the next positioning operation when the contents of register 14, as indicated by logic 34, is not zero, a clock logic 36 produces clock pulses CLK which transfer the count in the register 14 into the register 16. The transfer occurs one count at a time and is dependent on the relationship between the signs of the register so that the contents of the registers are algebraically summed before the movement of the machine element is initiated. The registers 14, 16 is a reversible up/down counter comprising a digital counter formed by a plurality of JK flip-flops coupled for successive enabling by the state of the preceding flip-flop and enabling input signals.