Active-Assistive Control Based on Dynamic Moving Window for Trajectory Tracking of an Upper Limb Exoskeleton in...

Area of Science:

• Biomedical Engineering
• Robotics
• Rehabilitation Science

Background:

• Rehabilitation robotics often uses fixed paths or passive guidance, limiting patient engagement and adaptability.
• Existing controllers struggle to balance robotic assistance with user-specific needs and voluntary movement.

Purpose of the Study:

• To develop and validate a novel active-assistive controller for upper-limb rehabilitation exoskeletons.
• To enable dynamic, patient-centered assistance that adapts to user effort and voluntary motion.

Main Methods:

• Integration of a virtual tunnel-based force mechanism with a dynamic moving-window technique for tracking activities of daily living (ADL) trajectories.
• Implementation on a wearable two-degree-of-freedom (DOF) upper-limb exoskeleton.
• Real-time dynamic adjustment of the virtual tunnel to permit movement within a safe range.

Main Results:

• Decreasing guidance force (Fgf) increased tracking errors (1° at 100% Fgf to 5° at 30% Fgf), indicating greater voluntary motion.
• Peak actuator torques decreased, confirming modulated robotic assistance (e.g., elbow: 14.75 to 13.43 Nm).
• Successful guidance along ADL trajectories with 30 healthy participants.

Conclusions:

• The proposed controller effectively modulates robotic assistance, allowing for personalized upper-limb rehabilitation.
• The system demonstrates potential for enhancing user engagement and adaptability in rehabilitation robotics.
• This approach supports patient-centered rehabilitation by accommodating voluntary movement and varying user effort.