This invention relates generally to interpolation methods, and more particularly, to a method for interpolating between a Cartesian coordinate axis system and an axis of rotation, and to the control of the axis of rotation, in numerically controlled machines.
A variety of designs for numerically controlled machines wherein interpolation in Cartesian coordinates is performed for track control are described in Siemens-Zeitschrift 1970, Supplement "Numerical Controls", FIG. 5, pages 7 and 52 to 62; and Siemens-Zeitschrift 1975, pages 346 to 350. Some known machine systems are provided with axes of rotation in addition to Cartesian feed axes. Such a combination of axial motion along Cartesian coordinates and a rotary axis permits special curves to be machined, illustratively helices, involutes, and others. It is a problem with such systems, however, that interpolation between the Cartesian and rotary coordinates is difficult, because the coupling of the two motions can be simply described by only a system of equations which is not easily adaptable to interpolation.
It is, therefore, an object of this invention to provide a method by which interpolation between rotary and Cartesian axes can be performed in a relatively simple manner, and the rotary axis can be accordingly controlled.