Improved prescribed performance control of a fast steering mirror based on switching strategy

Area of Science:

• Control Systems Engineering
• Optical Engineering
• Laser Communication Systems

Background:

• Fast steering mirrors (FSMs) are critical for high-performance laser communication systems.
• Existing control methods face challenges in meeting stringent tracking accuracy and disturbance rejection requirements.
• Prescribed performance control (PPC) offers constrained error tracking but can be fragile.

Purpose of the Study:

• To develop an improved control strategy for FSMs in laser communication.
• To enhance the robustness and stability of PPC methods.
• To achieve high-performance, constrained tracking control for FSMs.

Main Methods:

• A reduced-order nonlinear extended state observer (RESO) was designed to estimate and compensate for external disturbances.
• A prescribed performance control (PPC) law was formulated using a prescribed performance function for constrained tracking error.
• A switching fast nonsingular terminal sliding mode (FNT-SMC) control law was developed to enhance robustness and avoid singularity.
• Finite-time stability was proven using Lyapunov stability theory.

Main Results:

• The proposed control method effectively estimates and compensates for system disturbances.
• Constrained tracking error performance was achieved using the PPC law.
• The FNT-SMC law successfully addressed the fragility of PPC and avoided singularity.
• Comparative experiments demonstrated the effectiveness and superiority of the proposed approach.

Conclusions:

• The combined RESO and FNT-SMC based PPC method offers superior performance for FSMs in laser communication.
• The developed control strategy provides a robust and stable solution for high-performance optical instruments.
• This work serves as a valuable guide for designing controllers for precision optical systems.