Disturbance compensation based on harmonic injection switching for unknown time-delay systems.

Area of Science:

• Control Systems Engineering
• Signal Processing

Background:

• Unknown input time-delay and periodic disturbances pose significant challenges in control system stability and performance.
• Existing methods often require precise parameter estimation or known upper bounds for delay, limiting their applicability.

Purpose of the Study:

• To develop a robust disturbance rejection strategy for systems with unknown input delays and periodic disturbances.
• To achieve asymptotic compensation without relying on exact parameter values or known delay bounds.

Main Methods:

• Design of a characteristic observer to estimate parameters related to delay time and disturbance frequency.
• Development of switching criteria to validate estimated parameter regions.
• Utilizing reliable delay characteristics for disturbance reconstruction and prediction.

Main Results:

• The proposed method effectively reconstructs and predicts periodic disturbances.
• Asymptotic compensation is achieved even with imprecise parameter estimates.
• Quantitative stability analysis is enabled, unlike approximation approaches.

Conclusions:

• The novel strategy offers a robust solution for disturbance rejection in systems with unknown input delays.
• The method's independence from precise parameter knowledge and delay bounds enhances its practical applicability.
• Demonstrated effectiveness through a numerical example validates the proposed approach.