Patent GB-1090238-A (GB)
Title: Improvements in or relating to position control devices for machine tools and similar equipments
IPC: G05B19/37
Filed: 1964-10-02
Abstract: 1,090,238. Programmed machine control. ING. C. OLIVETTI & CO. S. p. A. Oct. 2, 1964 [Oct. 7, 1963], No.40114/64. Heading G3N. A position control device for a machine, wherein a member movable along at least two axes is positioned along a predetermined continuous trajectory under the control of a succession of positional orders, recorded in binary notation on a programme tape and representing a series of instantaneous positions of the member along said axes, is characterized by the bits of each order and associated address bits being recorded in parallel on a single transverse row of the tape. Control data is recorded on a tape, Fig. 2, in single rows, perpendicular to the tape feed direction. The rows X, Y, Z comprise ten bits P1-P10  of binary data relating to a co-ordinate of a point to be reached, two bits P11-P12 denote the axis address and a bit P13 is for parity checking. A row A has ten bits P1-P10 relating to an auxiliary operation, coolant, spindle speed, etc., two bits P11, P12 for the address and a parity bit P13. It is stated that the axes and auxiliary data can be recorded in any desired sequence and that the tape can be used in the reverse direction or produce a different shape. A work-table of the machine is positioned relative to a tool by servomotors SMX, SMY, SMZ, Fig. 1, responsive through amplifiers 19X, 19Y, 19Z to an error signal stored by capacitors 18X, 18Y, 18Z. The parallel data bits determine the state of bi-stable circuits F1-F13 and the timing signal the state of a bi-stable circuit F14. Circuits F1-F10 feed a digital to analogue converter 39 the output of which is connected to three position sensing transformer devices 1X, 1Y, 1Z. The address is simultaneously stored in bi-stable circuits F11 F12 and the data parity checked by a circuit 33 responsive to the outputs of circuits F1 -F13 to provide address signals from decoder 3. When a clock signal is stored on circuit F14 an oscillator 14 is triggered for five oscillations which are fed to digital to analogue converter 39 and to a pulse generator 15 which produces five sampling pulses which through a gate 21 and a gate 20X, considering the X axis only, is closed by an X signal from address decoder 3 to close a switch 17 to apply an amplifier error signal from amplifier 16X to the capacitor memory 18X. Positional error signal are only applied to the capacitor 18X when the change of error between successive determination is within set limits. The change of error is derived by a comparator circuit 25X responsive to the signal from amplifier 16X and the signal on capacitor 18X. The comparator output, through a sequence determining gate 27X, controls a bi-stable circuit 28 enabling the gate 21. The system is stopped when a not permissible sequence of changes of error outside the set limits occurs. This is effected by bi-stable circuits 30X- 20Z which are reset before each positional order and are responsive to signals from gates 27X-27Z which control a relay 32 for stopping the machine. It is stated that the system is also suitable for controlling the position of a workpiece in an inspection machine e. g. using the same programme tape as that for the manufacture of the workpiece, and for use with a plotting machine to reproduce on a paper sheet the contour recorded on a programme tape.