Tracking Control for Nonlinear Systems With Actuator Saturation via Interval Type-2 T-S Fuzzy Framework

Area of Science:

• Control Systems Engineering
• Fuzzy Logic Systems
• Nonlinear System Analysis

Background:

• Discrete-time nonlinear systems with actuator saturation pose significant control challenges.
• Interval Type-2 (IT2) T-S fuzzy systems offer improved uncertainty expression over Type-1 systems.
• Existing methods often underutilize membership function (MF) information, leading to conservative results.

Purpose of the Study:

• To develop a membership-functions-dependent (MFD) analysis approach for IT2 T-S fuzzy systems.
• To enhance the design flexibility and reduce the conservativeness of IT2 fuzzy controllers.
• To address stability analysis complexities arising from actuator saturation and IT2 fuzzy frameworks.

Main Methods:

• Approximation of IT2 MFs using piecewise linear functions.
• Incorporation of approximation errors into stability analysis.
• Conversion of actuator saturation to a sector nonlinear problem for LMI-based constraints.
• Inclusion of H∞ performance to bound system deviations.

Main Results:

• A novel MFD analysis approach is proposed for IT2 T-S fuzzy systems.
• The method allows for enhanced IT2 fuzzy controller design flexibility.
• Reduced conservativeness in stability analysis results is achieved.
• The approach effectively handles actuator saturation nonlinearities.

Conclusions:

• The developed MFD analysis approach is effective for discrete-time nonlinear actuator-saturated systems.
• The proposed method enhances IT2 fuzzy controller design and analysis.
• The results demonstrate improved tracking control performance and stability guarantees.