Virtual Physical Coupling of Two Lower-Limb Exoskeletons.

Area of Science:

• Robotics
• Biomechanics
• Rehabilitation Engineering

Background:

• Physical interaction is crucial for human motor learning and performance in shared tasks.
• Previous research on dyadic haptic interaction primarily focused on upper-limb robotic devices.
• A need exists for infrastructure enabling lower-limb physical interactions to explore new rehabilitation strategies.

Purpose of the Study:

• To design and develop a system for rendering haptic interactions between two users in multi-joint lower-limb exoskeletons.
• To investigate the feasibility of creating dyadic haptic feedback for lower-limb exoskeletons during walking.
• To establish a platform for studying the effects of haptic interaction on motor learning and gait rehabilitation.

Main Methods:

• Developed a system to command desired interaction torques to individual lower-limb exoskeletons based on user kinematics and virtual coupling properties.
• Implemented the infrastructure to render various haptic properties (e.g., soft, hard) and connection types (e.g., bidirectional, unidirectional).
• Tested connections expressed in both joint space and task space to evaluate system capabilities.

Main Results:

• Successfully demonstrated the platform's capacity to render different haptic properties and connection types.
• Observed synchronized movement between dyads when utilizing haptic connection.
• Found that increased virtual stiffness led to a decreased difference between joint angles.

Conclusions:

• This study presents the first instance of multi-joint dyadic haptic interactions using lower-limb exoskeletons.
• The developed platform provides a novel infrastructure for investigating dyadic lower-limb haptic interactions.
• This technology holds significant potential for advancing research in motor learning and gait rehabilitation through enhanced physical interaction.