Modified Hammerstein-Like Hysteresis Modeling and Composite Control Methods for Fast Steering Mirrors.

Area of Science:

• Aerospace Engineering
• Control Systems Engineering
• Materials Science

Background:

• Fast steering mirrors (FSMs) are crucial for satellite laser communication, enabling precise beam pointing and tracking.
• Piezoelectric ceramics, used to actuate FSMs, exhibit inherent hysteresis nonlinearity, degrading dynamic performance.
• Existing rate-dependent hysteresis and Hammerstein models have limitations in capturing complex dynamic behaviors.

Purpose of the Study:

• To develop an advanced model for characterizing hysteresis nonlinearity in piezoelectric-actuated FSMs.
• To propose a composite control strategy to mitigate the adverse effects of hysteresis on FSM dynamic performance.
• To validate the proposed modeling and control approaches through experimental testing.

Main Methods:

• A modified Hammerstein-like (MHL) model was developed, integrating input time delay, rate-dependent hysteresis, and linear dynamics.
• A composite control strategy was designed, comprising a feedforward compensator with a hysteresis inverse model and a PI controller.
• Experimental validation was conducted to assess the performance of the MHL model and the composite control strategy.

Main Results:

• The MHL model effectively captured the dynamic characteristics of hysteresis systems over a wide frequency range.
• The composite control strategy significantly improved the pointing and tracking accuracy of FSMs by compensating for hysteresis.
• Experimental results confirmed the efficacy of both the proposed modeling and control methods.

Conclusions:

• The developed MHL model provides a robust framework for understanding and predicting hysteresis in FSMs.
• The composite control strategy offers an effective solution for enhancing the dynamic performance of piezoelectric-actuated FSMs.
• This research contributes to improving the reliability and precision of laser communication systems in space applications.