H∞-Based Tracking Control for Nonlinear Systems With A Sampled-Data PI-Type Controller: A Nonuniform...

Area of Science:

• Control Engineering
• Nonlinear System Analysis
• Fuzzy Logic Systems

Background:

• Nonlinear systems present significant control challenges.
• Existing H-infinity control methods often have limitations with sampled-data systems.
• Takagi-Sugeno (T-S) fuzzy models offer a framework for approximating nonlinear dynamics.

Purpose of the Study:

• To develop an H-infinity-based tracking control strategy for nonlinear systems under nonuniform sampling.
• To address challenges posed by external disturbances, transmission delays, and packet dropouts.
• To relax constraints found in conventional control methods for sampled-data systems.

Main Methods:

• A nonuniform sampled-time-dependent functional (NSTDF) was proposed, overcoming limitations of traditional looped functionals.
• A novel H-infinity performance analysis theorem for sampled-data systems was derived, easing Lyapunov matrix constraints.
• An augmented system incorporating an error integral state was constructed for controller design.

Main Results:

• A proportional-integral (PI)-type controller was designed for the augmented system, effectively handling disturbances and delays.
• The H-infinity tracking control problem was successfully reformulated for the augmented system.
• The proposed methods demonstrated feasibility and advantages in simulations using a Wind Energy Conversion System (WECS) and Rossler's system.

Conclusions:

• The developed NSTDF and H-infinity analysis provide a more flexible framework for sampled-data control.
• The PI-type controller effectively manages complex system dynamics and uncertainties.
• The study offers a robust and efficient approach to H-infinity tracking control for nonlinear systems.