Robust disturbance rejection methodology for unstable non-minimum phase systems via disturbance observer

Area of Science:

• Control Systems Engineering
• System Dynamics and Stability

Background:

• Unstable non-minimum phase (NMP) systems present significant control challenges.
• Existing methods often struggle with robust disturbance rejection in these complex systems.

Purpose of the Study:

• To develop a disturbance rejection methodology for controlling unstable NMP systems.
• To enhance control performance and robustness against disturbances and uncertainties.

Main Methods:

• A two degrees-of-freedom control structure combining feedback control and a disturbance observer (DOB).
• Utilizing H₂ theory for controller design and H∞ method for DOB optimization.
• Synthesizing relative order, robust internal stability, and mixed sensitivity optimization.

Main Results:

• The proposed DOB optimization method ensures robust internal stability and meets design requirements.
• Simulations demonstrate effective control system design for unstable NMP systems.
• The new method exhibits superior performance compared to traditional approaches.

Conclusions:

• The developed methodology provides a systematic approach for designing controllers for unstable NMP systems.
• The integrated disturbance rejection strategy significantly improves system performance and robustness.