Tracking control system

A tracing control system for controlling the machining of a work piece by a cutter head which is movable along respective cutting axes of a first three dimensional coordinate system in accordance with tracing of a model by a tracer head having a stylus which contacts the model, the tracer head being movable selectively along respective tracing axes of a second three dimensional coordinate system and the stylus being displacable, relatively to the tracer head and resultant from forces applied to the stylus by the model, said tracing control system comprising:

• calculating means for calculating an actual position of the tracer head relative to the first three dimensional coordinate system;
• cutter head actuating means for actuating the cutter head for selective movement along the respective cutting axes of the first coordinate system;
• tracer head actuating means for actuating the tracer head for selective movement along the respective tracing axes of the second coordinate system, independently of movement of the cutter head within the first three dimensional coordinate system;
• speed command supply means for supplying respective tracer head speed commands to the tracer head actuating means and cutter head speed commands to the cutter head actuating means, respectively defining the actuating thereby, and the resultant, corresponding movements of the tracer head and the cutter head;
• stylus displacement detection means, associated with the tracer head, for detecting displacements of the stylus relatively to the tracing head along the respective tracing axes of the second coordinate system and producing corresponding displacement signals related to the respective tracing axes;
• and
• correcting means for correcting the cutter head speed commands in accordance with the displacement signals and for supplying the thus corrected cutter head speed commands to the cutter head actuating means thereby to actuate the cutter head for movement along the respective cutting axes of the first coordinate system in accordance with the corrected cutter head speed commands.