Dual Predictive Control Improves a High-speed Precision Numerically Controlled Tapping.

A new control algorithm for a numerically controlled tapping is proposed. This algorithm uses two predictive controls. The Z-axis servo has a predictive control and the spindle response is also predicted. By doing so we achieve precise synchronization between the spindle-axis and the Z-axis not only constant velocity phase but also while accelerating and decelerating. An experiment using this algorithm achieved 625 rev/s2 acceleration and deceleration, 6000 rpm maximum speed and 10μm precision.