Design of Active Vibration Isolation Controller with Disturbance Observer-Based Linear Quadratic Regulator for...

Area of Science:

• Physics
• Engineering
• Optics

Background:

• Space-based ultrastable lasers are crucial for high-precision applications.
• Optical reference cavities in these lasers are highly sensitive to microvibrations.
• Platform vibrations degrade laser accuracy and frequency stability.

Purpose of the Study:

• To develop and validate an active vibration isolation controller for ultrastable lasers.
• To mitigate the impact of microvibrations on laser cavity length variations.
• To enhance the frequency stability of lasers operating in space environments.

Main Methods:

• Designed a decentralized control strategy using a state-differential feedback controller.
• Incorporated a linear quadratic regulator (LQR) for optimal control.
• Integrated a disturbance observer (DOB) to estimate and compensate for source noise.

Main Results:

• Experimental validation of the active vibration isolation system.
• Significant suppression of accelerations along Z, X, and Y axes within the low-frequency band (<200 Hz).
• Reduced root-cumulative power spectral densities (PSDs) to levels meeting ultrastable laser requirements (e.g., 1.17 × 10^-5 g on Z-axis).

Conclusions:

• The proposed active vibration isolation controller is feasible and effective.
• The system successfully reduces microvibration effects on ultrastable lasers.
• This technology meets the stringent vibration isolation requirements for space-based laser systems.