Disturbance observer-based controller design for uncertain nonlinear parameter-varying systems.

Area of Science:

• Control Theory
• Nonlinear Systems
• System Identification

Background:

• Nonlinear parameter-varying (NPV) systems present significant control challenges due to uncertainties.
• Unmeasurable state variables and unknown disturbances complicate controller design.
• Existing methods often struggle with independent handling of these complex system dynamics.

Purpose of the Study:

• To develop a robust disturbance observer-based controller (DOBC) for uncertain nonlinear parameter-varying (NPV) systems.
• To address challenges posed by unknown uncertainties and unmeasurable state variables.
• To simplify the complexity of disturbance-based control algorithms.

Main Methods:

• An efficient scheme to treat unknown uncertainty as a disturbance.
• A novel observer for estimating unmeasurable states and unknown disturbances.
• Design of a state-and-parameter-dependent (SAPD) controller using Lyapunov stability theory and linear matrix inequalities (LMIs).
• Utilization of sum-of-squares (SOS) techniques for solving LMIs.

Main Results:

• Independent design of the SAPD controller and observer, reducing algorithmic complexity.
• Feasibility demonstrated through simulations and comparative analysis in two distinct examples.
• Established SAPD conditions for observer and controller design via LMIs.

Conclusions:

• The proposed DOBC approach is effective for uncertain NPV systems.
• Independent design of observer and controller simplifies practical implementation.
• The method offers a feasible and efficient solution for complex control problems.