Method for automatic generation of moving curve-point coordinates, and arrangement for application of said method in controlling, for instance, movement mechanisms

摘要

1,013,848. Digital interpolators. SENTRALINSTITUTT FOR INDUSTRIELL FORSKNING. Aug. 31, 1962 [Aug. 31, 1961], No. 33555/62. Heading G4A. [Also in Division G3] In a digital interpolator for use in a machine tool control system, the controlled point moves on a curve whose gradient at any point depends on the ratio of two curve parameters, one parameter being added and the other subtracted in a common arithmetic unit, an addition being followed by an elementary step in one coordinate direction and a subtraction by an elementary step in the other co-ordinate direction, additions and subtractions taking place according as the content of the arithmetic unit is negative or positive respectively. If the parameters are kept constant, a straight line is generated, but if they are varied other curves such as circles or parabolas will be produced. All the curves generated are solutions of equations of the form where m, n, p, q are 0, + 1 or- 1. Numbers representing the initial values of the two curve parameters are fed from punched tape to the X-register and Y-register shown in Fig. 2. The contents of the X-register is subtracted from or the contents of Y-register is added to, the contents of an accumulator ACC according as accumulator content is positive or negative, as determined by a " carry " flpi-flop Cad. The addition or subtraction (by complementary addition) takes place in a serial adder AD. If a subtraction takes place an X-servo moves one step and if an addition takes place, a Y-servo moves one step. The contents of the X and Y registers may be modified at each step in addersubtractors ASX, ASY if it is desired to generate a circle or a parabola, the control signals for the modification being derived from the punched tape. The modification may be positive or negative depending on the quadrant concerned, a change of quadrant being detected by " zero test " circuits ZX, ZY. The attainment of the end point of the curve is detected when #X and #Y register, which originally contained numbers representing co-ordinate differences between the end point and starting point, reach zero.