| 摘要 |
An object of the present invention is to provide a numerical control unit which commands definition data of free curved line to directly interpolate a free curved line and also holds down various errors which occurs during the aforesaid process within each allowable value. In the present invention, a program 11 which defines a moving locus with a curved line P(t) represented by the given parameter t is decoded and working commands according to the moving locus are outputted to servo systems 12, 13, and 14 to be controlled. In the output, the curved line P(t) of moving locus is interpolated in a curved line interpolating section 16. In the interpolation, an allowable error Emax in working results and error factors omega o, M and K for reference in a data setting section 21, a radius of curvature R(t) of the curved line P(t) is calculated in a radius of curvature calculating section 22, and maximum feed allowable speed Fmax less than an allowable error is calculated from the radius of curvature and the error factors in an allowable speed calculating section 23. In a command speed limiting section 24, when the allowable speed Fmax is lower than command speed CF of working command, command speed in the curved line interpolating section 16 is limited to the allowable speed Fmax, thus preventing a error by excessive speed.
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