Robust Control of a Cable-Driven Soft Exoskeleton Joint for Intrinsic Human-Robot Interaction

Area of Science:

• Robotics
• Biomechanics
• Rehabilitation Engineering

Background:

• Robotic exoskeletons require compliant joints for safe and effective human-robot interaction.
• Existing rigid joints can cause discomfort and limit applicability in rehabilitation.

Purpose of the Study:

• To introduce a novel cable-driven soft joint for robotic exoskeletons.
• To develop and validate a robust low-level torque controller for the soft joint.
• To assess the joint and controller's potential in physiotherapy settings.

Main Methods:

• Modeling the torque-displacement characteristics of the soft elastomeric core.
• Deriving a sliding mode controller (SMC) using dynamic system models.
• Experimental comparison of SMC with a feedback-linearised proportional-derivative controller.
• Testing the controller with healthy subjects during activities of daily living and a case study with a spastic cerebral palsy participant.

Main Results:

• The soft joint enables intrinsic and comfortable human-robot interaction.
• The SMC controller demonstrated robustness to un-modeled disturbances compared to the baseline controller.
• Controller performance was validated across various conditions and daily living activities.
• The system showed potential for assisting clinical populations in physiotherapy.

Conclusions:

• The developed cable-driven soft joint and SMC offer a promising solution for comfortable and effective robotic rehabilitation.
• The controller's robustness and validated performance support its use in assistive technologies.
• This technology has significant potential for improving physiotherapy interventions for individuals with neurological conditions.