| 摘要 |
A numerical control device for positioning a movable member includes an interpolation unit which effects numerical control by circular interpolation, approximating the arc of a circle by a series of straight line segments. Referred to the origin of the circle, the incremental displacement components required to move from any point (xi, yi) on the circle are shown to be yi/K along the x-axis and xi/K along the y-axis, where K is a predetermined factor. The interpolation unit operates in a succession of phases corresponding to said segments and includes means to divide said coordinates (xi, yi) by K, and means for summing said resultants to form summations ( SIGMA xi/K, SIGMA xi/K ). The error in approximating to said arc is maintained below a predetermined maximum by starting a new interpolation phase whenever SIGMA xi/K or SIGMA yi/K reaches a predetermined value. The interpolation unit also includes means for summing the components DELTA xi, DELTA yi of the path segments corresponding to successive interpolation phases. To limit the speed of the member, the interpolation unit sums the incremental displacement components (xi/K, yi/K) over a time cycle comprising several interpolation phases. The interpolation is stopped if the summation of either of the displacement components reaches a predetermined value corresponding to a maximum velocity component.
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