Optimal Controller Design for Ultra-Precision Fast-Actuation Cutting Systems

Micromachines

Duo Li¹  Fei Ding¹  Bo Wang¹  Zheng Qiao¹  Xichun Luo² 

[1] Centre for Precision Engineering, Harbin Institute of Technology, Harbin 150001, China;Centre for Precision Manufacturing, Department of DMEM, University of Strathclyde, Glasgow G1 1XJ, UK;

关键词: optimal control;    ultra-precision machining;    microstructure;    controller tuning;    fast tool servo;   

DOI  :  10.3390/mi13010033

来源: DOAJ

【 摘 要 】

Fast-actuation cutting systems are in high demand for machining of freeform optical parts. Design of such motion systems requires good balance between structural hardware and controller design. However, the controller tuning process is mostly based on human experience, and it is not feasible to predict positioning performance during the design stage. In this paper, a deterministic controller design approach is adopted to preclude the uncertainty associated with controller tuning, which results in a control law minimizing positioning errors based on plant and disturbance models. Then, the influences of mechanical parameters such as mass, damping, and stiffness are revealed within the closed-loop framework. The positioning error was reduced from 1.19 nm RMS to 0.68 nm RMS with the new controller. Under the measured disturbance conditions, the optimal bearing stiffness and damping coefficient are $1.1\times {10}^5\mathrm{N}/\mathrm{m}$ and $237.7\mathrm{N}/\left(\mathrm{m}·{\mathrm{s}}^{-1}\right)$, respectively. We also found that greater moving inertia helps to reduce all disturbances at high frequencies, in agreement with the positioning experiments. A quantitative understanding of how plant structural parameters affect positioning stability is thus shown in this paper. This is helpful for the understanding of how to reduce error sources from the design point of view.

【 授权许可】

Unknown