Tracer control system

A tracer control system for controlling the relative position of a tracer head with respect to a model to be traced by displacement signals from said tracer head by moving said tracer head in at least one selected plane perpendicular to the X-Y plane in a coordinate system corresponding to the displacement signals of said tracer head, each said selected plane being predetermined by selecting a corresponding feed axis in said X-Y plane, the direction of each said feed axis being determined by specifying the corresponding angle of intersection of each said selected plane and the X-Z plane of said coordinate system, said system comprising:

• means for providing input signals comprising selected trigonometric functions of each said angle of intersection;
• a first coordinate conversion circuit comprising multipliers for selectively multiplying said input signals representative of each said angle of intersection with the respective displacement signals of the tracer head corresponding to the X and the Y axes, and adding means for selectively adding together output signals from the multipliers to output each respective component of the resultant displacement signal along each said respective selected feed axis in the X-Y plane;
• a displacement direction index circuit for outputting selected trigonometric functions of the angle between the X-Y plane and the projection of said displacement signal in said at least one selected plane, said index circuit comprising means for utilizing the output from the first coordinate conversion circuit corresponding to said at least one selected plane and the tracer head displacement signal along the Z-axis to provide said output of the index circuit;
• a control signal distributing circuit which is supplied with a normal velocity signal and a tangential velocity signal derived from the resultant displacement signal corresponding to the tracer head displacement signals along the X-, Y- and Z-axes and the output signal from the displacement direction index circuit to provide a velocity signal component along said at least one feed axis and a velocity signal component along the Z-axis for said tracing of said model in said at least one selected plane;
• a second coordinate conversion circuit composed of multipliers for multipying the feed axis velocity signal from the control signal distributing circuit and the signals representative of the direction of said at least one selected feed axis in the X-Y plane, and means for distributing control signals indicative of the corresponding feed rates along the X- and Y-axes in accordance with the signals representative of the direction of the at least one selected feed axis.