A NEW SAMPLED-DATA DRIVE FOR CNC MACHINE-TOOLS

A mathematical analysis of a sampled-data servo-drive system controlle d by the step control algorithm for computer numerical control (CNC) i s presented. The step control algorithm provides for rapid and precise positioning and is ready for practical implementation. Its performanc e, including stability, damping ratio, maximum overshooting, steady-st ate error for both the step and ramp input, and bandwidth for accurate circular motion, is studied and depicted in design charts. The design procedure proceeds by using the design charts to choose the weighting factor and the sampling period to satisfy the specifications of the s ystem. The effectiveness of the proposed control algorithm is demonstr ated by simulation and experiment.