An Unpowered Exoskeleton Enabling Cross-Limb Energy Transfer From Arm Swing to Assist Contralateral Ankle...

Area of Science:

• Biomechanics
• Robotics
• Human Gait Analysis

Background:

• Unpowered exoskeletons typically recycle energy within the lower limbs for walking assistance.
• The role of arm swing as a mechanical energy source for gait assistance is largely unexplored.
• Human gait involves coupled movements between upper and lower limbs.

Purpose of the Study:

• To propose and test a cross-limb energy transfer concept using arm swing to assist ankle function.
• To develop a novel unpowered exoskeleton for redirecting mechanical work from arm swing to the contralateral ankle.
• To evaluate the effectiveness of this exoskeleton in reducing biological effort and enhancing gait.

Main Methods:

• Development of a novel unpowered exoskeleton with waist-mounted force-routing and shank-ankle modules.
• Treadmill walking experiments with 7 participants under various conditions.
• Quantification of exoskeleton torque, spatiotemporal gait parameters, kinematics, and muscle activity (soleus).

Main Results:

• The exoskeleton provided phase-appropriate ankle plantarflexion assistance without altering gait stability or coordination.
• Average soleus muscle activity was reduced by 11.1% compared to normal walking, indicating effective biological off-loading.
• Arm swing integration provided additional energy contribution beyond lower-limb energy recycling.

Conclusions:

• Cross-limb energy transfer is feasible in unpowered exoskeletons for gait assistance.
• Leveraging coordinated whole-body motion offers a new paradigm for expanding energy pathways in assistive devices.
• This approach demonstrates a novel method for enhancing locomotor function by utilizing active mechanical contributions from upper body movement.