Global practical tracking control via output feedback for more general nonlinear systems.

Area of Science:

• Control Systems Engineering
• Nonlinear Dynamics
• Adaptive Control Theory

Background:

• Uncertain nonlinear systems pose significant challenges in control engineering.
• Existing tracking control methods often require knowledge of parameter bounds, limiting their applicability.
• Output feedback control is desirable for practical implementation but complicates controller design.

Purpose of the Study:

• To develop a global practical tracking control strategy for uncertain nonlinear systems using output feedback.
• To address systems with unknown control coefficients and unknown reference signals.
• To overcome limitations of existing methods by not requiring bounds on unknown control coefficients.

Main Methods:

• A novel adaptive tracking controller is designed using a dynamic high gain approach.
• The controller integrates universal control principles with dead-zone concepts and backstepping techniques.
• The method effectively manages uncertainties arising from unknown coefficients and nonlinearities.

Main Results:

• The designed adaptive controller guarantees global boundedness of the closed-loop system states.
• Tracking errors are shown to converge to an arbitrarily small neighborhood of the origin in finite time.
• The controller's effectiveness is validated through two numerical examples.

Conclusions:

• The proposed adaptive output feedback control strategy is effective for uncertain nonlinear systems.
• The method offers a robust solution without requiring prior knowledge of parameter bounds.
• This work advances the field of practical tracking control for complex systems.