Numerical control system

PCT No. PCT/JP81/00314 Sec. 371 Date Jun. 18, 1982 Sec. 102(e) Date Jun. 18, 1982 PCT Filed Oct. 29, 1981 PCT Pub. No. WO82/01600 PCT Pub. Date May 13, 1982.Ordinarily, an interpolator (102) executes pulse calculations on the basis of a movement command from a command tape (101), to generate the respective distributed pulses XP, YP, ZP, BP and CP of cartesian coordinate axes and spherical coordinate axes, and these pulses drive corresponding servomotors (113)-(117) through servo circuits (108)-(112). In order to keep the relative position between the nose of a tool and a workpiece unchanged in a manual operation, a tool holder is positioned in the cartesian coordinate system, whereupon manual pulses in the B-axial or C-axial direction are generated by a manual pulse generator (103). Then, the distributed pulses BP and CP are generated through the interpolator (102) and rotate the servomotors (116) and (117). The distributed pulses are simultaneously impressed on a compensation circuit (104), which calculates the compensation pulses XHP, YHP and ZHP so as to drive the servomotors with pulses obtained by adding the compensation pulses to the distributed pulses.