Sliding mode fault-tolerant control for manipulator based on predefined time extended state observers.

Area of Science:

• Robotics
• Control Systems Engineering
• Mechatronics

Background:

• Multi-joint manipulator systems face challenges from actuator faults, parameter perturbations, and external disturbances.
• Accurate and fast-tracking control is crucial for manipulator performance in dynamic environments.
• Existing control methods may struggle with composite uncertainties and abrupt system changes.

Purpose of the Study:

• To develop a robust fault-tolerant control (FTC) scheme for multi-joint manipulators.
• To address uncertainties including actuator faults, parameter variations, and external disturbances.
• To achieve accurate and fast-tracking control within a predefined time.

Main Methods:

• Design of a novel Extended State Observer (ESO) for estimating time-varying composite disturbances within a predefined time.
• Development of a predefined time integral sliding mode surface and a Finite Time prescribed performance constraint function.
• Introduction of a continuous function to mitigate chattering phenomena in the control signal.
• Application of Lyapunov stability theory to analyze the predefined time stability of the closed-loop system.

Main Results:

• The proposed Extended State Observer effectively estimates composite disturbances in predefined time.
• The integrated control strategy ensures robust tracking performance under various uncertainties.
• Numerical simulations demonstrate strong robustness, high steady-state accuracy, and resilience to actuator failures.
• Chattering is significantly reduced by the continuous function, improving control smoothness.

Conclusions:

• The proposed fault-tolerant control scheme, based on a predefined time Extended State Observer, offers effective and robust control for multi-joint manipulators.
• The method successfully handles actuator faults, parameter perturbations, and external disturbances, ensuring high tracking accuracy and system stability.
• This approach provides a reliable solution for complex manipulator control applications requiring high performance and fault tolerance.