Project - Ultra-High Performance Fast Tool Servos for Diamond Turning

Ultra-High Performance Fast Tool Servos for Diamond Turning


Xiaodong Lu
Augusto Barto


National Science Foundation

We have designed, implemented, and tested an electromagnetically driven fast tool servo for diamond turning precision contoured surfaces with nanometer resolution. Our device is based on a novel ultrafast motor utilizing permanent magnets for flux bias in conjunction with steering coils used to control the actuator force. Experimental results demonstrate that our ultrafast tool servo has a stroke of 30 micrometers, achieves 23kHz closed-loop bandwidth, as low as 1.7nm RMS tracking error, 500G peak acceleration at 10kHz open-loop operation, and 2.1nm (0.04%) error in tracking a 3kHz sinusoid of 16mm p-v. To drive and control this ultrafast tool servo, a 1kW linear power amplifier and a high-speed real-time computer with 1MHz sampling rate have been designed and implemented.


This project is funded by National Science Foundation under Grant award number DMI-0322590.


Manufacturing free-form optical surfaces increasingly requires fast tool servos with higher bandwidth, higher acceleration, and higher accuracy. As an alternative solution to conventional piezo-based micro-positioning devices, electromagnetic actuators working on normal stress can potentially achieve much better performance than existing state of fast tool servo technology.



Design ultra-high performance fast tool servos based on novel electromagnetic actuators, high performance precision power amplifiers, and high performance real-time computers.


Our fast tool servos performance: 23kHz closed-loop bandwidth, 1.7 nm RMS positioning error, 2.1 nm RMS error for tracking 16 micron peak-to-valley sinewave at 3k Hz, 500 G acceleration up to 10 kHz.

Our linear amplifier has 100kHz band and 1 kW.

Our real-time computer has achieved 1 MHz sampling rate for a control loop including 16-bit A/D, control algorithm calculation, and 16-bit D/A.UFTS Results


Xiaodong Lu, David L. Trumper, "UltraFast Tool Servos for Nano-Surfaces", Proceedings of ASPE 2004 Annual Meeting, Orlando, FL.

Xiaodong Lu, David L. Trumper, "Ultrafast Tool Servos for Diamond Turning", Annals of the CIRP 2005, accepted for publication.