  The fabric-based pneumatic exosuit is now a hot research topic because it is
lighter and softer than traditional exoskeletons. Existing research focused
more on the mechanical properties of the exosuit (e.g., torque and speed), but
less on its wearability (e.g., appearance and comfort). This work presents a
new design concept for fabric-based pneumatic exosuits Volume Transfer, which
means transferring the volume of pneumatic actuators beyond the garments
profile to the inside. This allows for a concealed appearance and a larger
stress area while maintaining adequate torques. In order to verify this
concept, we develop a fabric-based pneumatic exosuit for knee extension
assistance. Its profile is only 26mm and its stress area wraps around almost
half of the leg. We use a mathematical model and simulation to determine the
parameters of the exosuit, avoiding multiple iterations of the prototype.
Experiment results show that the exosuit can generate a torque of 7.6Nm at a
pressure of 90kPa and produce a significant reduction in the electromyography
activity of the knee extensor muscles. We believe that Volume Transfer could be
utilized prevalently in future fabric-based pneumatic exosuit designs to
achieve a significant improvement in wearability.
