Adaptive Continuous Integral-Sliding-Mode Controller for Wearable Robots: Application to an Upper Limb Exoskeleton

Area of Science:

• Robotics
• Control Systems Engineering
• Biomedical Engineering

Background:

• Exoskeletons require robust control strategies for safe and effective rehabilitation.
• Existing controllers often rely on precise models, which are not always available in real-world applications.
• Unknown dynamics and external disturbances pose significant challenges in exoskeleton control.

Purpose of the Study:

• To introduce an adaptive integral sliding mode controller (AISMC) for exoskeleton systems.
• To address control challenges arising from unknown system functions and parameter bounds.
• To ensure precise trajectory tracking (position, velocity, acceleration) in rehabilitation exoskeletons.

Main Methods:

• Controller design based on Lyapunov stability theory.
• Utilizing adaptive control techniques to handle unknown system dynamics.
• Implementing the controller on a 2-DOF upper limb exoskeleton for real-time validation.

Main Results:

• Demonstrated closed-loop stability of the controlled exoskeleton system.
• Verified the controller's ability to ensure convergence for position, velocity, and acceleration.
• Successfully validated the controller's effectiveness in a real-time rehabilitation scenario.

Conclusions:

• The proposed adaptive integral sliding mode controller offers a robust solution for exoskeleton control.
• The controller guarantees system stability and accurate trajectory tracking under bounded uncertainties.
• The approach enhances user safety and effectiveness in upper limb exoskeleton-assisted rehabilitation.