Design and Control of a Piezoelectrically Actuated Fast Tool Servo for Diamond Turning of Microstructured Surfaces

• Published in: IEEE transactions on industrial electronics (1982) Vol. 67; no. 8; pp. 6688 - 6697
• Main Authors: Zhu, Zhiwei, Chen, Li, Huang, Peng, Schonemann, Lars, Riemer, Oltmann, Yao, Jianyong, To, Suet, Zhu, Wu-Le
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bandwidth; Compliant mechanism; Control theory; Cutting force; Design optimization; Diamond; Diamond machining; Diamond tools; diamond turning; disturbance observer; Disturbance observers; fast tool servo (FTS); Feedforward control; Finite element method; Force; microstructured surface; Microstructured surfaces; Nyquist plots; Proportional integral derivative; Servomotors; Trajectory; Turning; Turning (machining)
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2019.2937051

This article reports on the mechanism design, dimension optimization, closed-loop control, and practical application of a piezoelectrically actuated fast tool servo (FTS) for the diamond turning of microstructured surfaces. With the mechanism, a finite-element based analytical model is developed to theoretically relate the working performance with its structural dimensions. Considering its application for micro/nanocutting, the structural dimensions of the mechanism are deliberately determined through evolutionarily optimizing a comprehensive objective. To ultrafinely track the cutting trajectory with a high bandwidth, a proportional-integral-derivative controller together with the dynamics inversion based feedforward compensation is optimally designed with assistance of the Nyquist diagram, and a disturbance observer is further employed to compensate for the inherent hysteresis nonlinearity as well as external cutting force disturbances. Both open-loop and closed-loop experimental tests on the prototype suggest that a stroke of 18 <inline-formula><tex-math notation="LaTeX"> \mu</tex-math></inline-formula>m and a closed-loop bandwidth of 1730 Hz are achieved. Taking advantage of the newly developed FTS, two typical microstructured surfaces are ultraprecisely turned, well demonstrating the effectiveness of the FTS.