A Bionic Pneumatic Shoulder Exosuit for Multi-DOF Assistance and Load-Bearing Augmentation in Rehabilitation

The shoulder joint is pivotal for upper-limb kinematics, yet individuals with post-stroke hemiparesis often require external shoulder support because of impaired motor control, excessive gravitational loading, and the risk of glenohumeral complications. Existing rehabilitation exoskeletons still face challenges in combining compliant movement assistance with sufficient antigravity load support.

This study proposes a Pneumatic Shoulder Exosuit (PSE) designed to provide compliant multi-DOF shoulder assistance and augment load-bearing capacity during rehabilitation. The dual functionality is enabled by two coupled pouch-based pneumatic actuator modalities configured into a bionic agonist/antagonist architecture. Device performance was evaluated through experiments with 10 healthy volunteers using kinematic assessment, standardized trajectory-tracking, and static overhead weight-holding tasks. In addition, 7 participants with post-stroke hemiparesis were enrolled to evaluate the feasibility and usability of the PSE during assisted shoulder tasks.

The experimental results showed that the PSE can provide gravity support with up to 24 Nm of torque. The device maintained the movement trajectory with a 96.5% similarity compared to unassisted. It also reduced agonist muscle activities (anterior, middle, and posterior deltoids and biceps brachii) by up to 65% with a 70% reduction in compensatory muscle (latissimus dorsi) activity, and a 45% reduction in peak lateral trunk tilt. The participants with post-stroke hemiparesis also provided positive feedback.

These findings demonstrate that the PSE can combine load-bearing augmentation with kinematic transparency during shoulder assistance.

The PSE suggests potential for compliant rehabilitation-oriented shoulder support in future clinical and home-based rehabilitation studies.