Dual-axis control of flexure-based motion system for optical fibre transceiver assembly using fixed-order controller

Area of Science:

• Control Engineering
• Mechatronics
• Precision Engineering

Background:

• Flexure-based motion systems are crucial for precision tasks like optical fibre alignment.
• High-frequency resonant modes in these systems limit motion and positioning accuracy.
• Existing control methods often struggle to simultaneously address resonant modes across multiple axes.

Purpose of the Study:

• To develop a fixed-order controller for flexure-based motion systems used in optical fibre transceiver alignment.
• To design a single controller capable of stabilizing uncertain high-frequency resonant modes for both X and Y-axis motions.
• To enhance low-frequency tracking and disturbance rejection capabilities.

Main Methods:

• Introduction of finite-frequency specifications for robust control of polytopic systems.
• Development of a practical method for selecting central polynomials, utilizing separate polynomials for X and Y axes.
• Design of a nominal controller to reduce conservatism in performance optimization.

Main Results:

• The proposed fixed-order controller effectively stabilizes high-frequency resonant modes in a 2-DOF flexure-based system.
• Experimental results demonstrate over a 50% reduction in tracking error compared to traditional notch filter controllers.
• The controller significantly improves both tracking accuracy and disturbance rejection abilities.

Conclusions:

• The finite-frequency specifications approach offers a less conservative method for robust control design.
• The developed fixed-order controller provides a practical and effective solution for enhancing precision in flexure-based motion systems.
• This method shows significant potential for applications requiring high-accuracy alignment, such as in optical fibre communications.