Observer-Based Fixed-Time-Synchronized Control for Uncertain Euler-Lagrange Systems With Bias-Actuator Faults.

Area of Science:

• Control Systems Engineering
• Robotics
• Nonlinear Dynamics

Background:

• Euler-Lagrange (EL) systems are fundamental in robotics and mechanics but susceptible to uncertainties, actuator faults, and external disturbances.
• Achieving synchronized tracking control with guaranteed convergence time, especially under adverse conditions, remains a significant challenge.

Purpose of the Study:

• To develop an observer-based fixed-time-synchronized tracking control strategy for EL systems.
• To address uncertain dynamics, bias-actuator faults, and external disturbances.
• To ensure tracking errors converge to zero within a fixed time, independent of initial conditions.

Main Methods:

• A novel fixed-time observer is proposed to reconstruct actuator faults and system uncertainties.
• A sliding mode variable with a norm-normalized sign function is designed for fast convergence.
• A robust control law is developed using observer information and the sliding mode variable.

Main Results:

• The proposed observer guarantees zero observation error within a fixed time.
• The control law ensures fixed-time stability and synchronized tracking for EL systems.
• Convergence time boundaries are independent of initial system states.

Conclusions:

• The developed observer and control schemes effectively handle actuator faults, external disturbances, and uncertain dynamics.
• The method guarantees all tracking errors converge to the origin simultaneously within a fixed time.
• Simulations validate the effectiveness and robustness of the proposed approach.