Tracer control equipment

Claim 1

A tracer control device which calculates a trace direction and a trace velocity for tracing control using displacement signals from a tracer head tracing the surface of a model and a predetermined desired value for a composite displacement signal, and which performs the tracing control for tracing the model by moving the tracer head selectively along a plurality of machine axes of said device in accordance with the calculated trace direction and trace velocity values, said device comprising: a memory for storing predetermined numerical command data in digital form for providing selective numerical control of the position of said tracer head apart from said tracing control; an analog gate circuit including means for being selectively operated for said tracing control and for said numerical control of the position of said tracer head, and having outputs for selectively driving said tracer head along said machine axes of said device for tracing control and for said numerical control of the position of the tracer head; and control means, including a processor, for determining whether said tracing control or said numerical control of the position of the tracer head is to be performed, for selectively reading out the numerical command data from the memory, and for performing said numerical control of the position of the tracer head in accordance with the selected numerical command data; wherein said control means comprises: means for selectively operating said analog gate circuit for said tracing of said model and for said numerical control of the position of the tracer head; a buffer register in which the processor sets digital data corresponding to a direction and velocity of the motion of the tracer head according to the selected numerical command data for performing said numerical control of the position of the tracer head; A D-A converter for converting said digital data set in the buffer register to a respective analog signal, and to provide each said analog signal to said analog gate circuit to selectively drive said tracer head along said machine axes for performing said numerical control of the position of said tracer head; a plurality of servo motors and respectively coupled position detectors, for providing motion of said tracer head along the respective machine axes of the tracer control device for said numerical control of the position of the tracer head, and means for driving each said servo motor according to each respective analog signal as a velocity command signal, each said position detector providing output pulses corresponding to the distance moved along respective machine axes; and a respective reversible counter for counting the output of each said position detector; wherein said control means selectively reads the count content of each said respective reversible counter for comparing the count content with respective numerical command data stored in the memory, for providing said numerical control of the position of the tracer head.