Ultrafast tool servos for diamond turning

This paper presents the design, implementation and control of a new class of fast tool servos, based on a novel ultrafast motor concept. A prototype ultrafast tool servo with a stroke of 30 mu m is described. Experimental results demonstrate that the ultrafast tool servo achieves 23 kHz closed-loop bandwidth, as low as 1.7 nm RMS error, 500 G peak acceleration at 10 kHz open-loop operation, and 2.1 nm (0.04%) error in tracking a 3 kHz sinusoid of 16 mu m p-v. A 1 kW linear power amplifier and a 1 MHz sampling rate high-speed real-time computer are designed to drive and control this ultrafast tool servo. A digital controller including loop shaping and adaptive feedforward cancellation is designed to control the tool motion.