Prescribed-Time Output-Feedback Tracking Control of a Class of Time-Varying Output-Constrained Systems

Area of Science:

• Control Theory
• Robotics
• System Dynamics

Background:

• Addressing control challenges in time-varying systems with output constraints and unknown disturbances is crucial for practical applications.
• Existing methods often require full state information or knowledge of disturbance bounds, limiting their applicability.
• Prescribed-time control offers finite-time convergence guarantees, which is desirable for many engineering systems.

Purpose of the Study:

• To develop a prescribed-time output-feedback tracking control scheme for time-varying output-constrained systems with unknown disturbances.
• To design a novel time-varying state observer and barrier Lyapunov functions (BLFs) for handling output constraints.
• To demonstrate the controller's ability to achieve zero tracking error within a prescribed time without needing full state information or disturbance bounds.

Main Methods:

• Construction of a novel time-varying state observer using a parametric Lyapunov equation (PLE) and a time-varying high-gain function.
• Definition of prescribed-time output-constrained functions and development of time-varying barrier Lyapunov functions (BLFs).
• Design of a time-varying high-gain output-feedback tracking control scheme leveraging the observer and BLFs.

Main Results:

• The proposed controller successfully drives the tracking error of the time-varying output-constrained system to zero within a prescribed time, even under unknown disturbances.
• The control scheme does not require prior knowledge of the system's full state or the bounds of external disturbances.
• Effectiveness validated through application to a single-link robot system with supporting numerical simulations.

Conclusions:

• The developed prescribed-time output-feedback control strategy effectively addresses tracking control for time-varying output-constrained systems with unknown disturbances.
• The method provides a robust solution that guarantees finite-time convergence of tracking errors, enhancing system performance and reliability.
• The successful application to a robotic system highlights the practical utility and potential of this control approach in real-world scenarios.