Portable pneumatic systems for 2 degree-of-freedom (DOF) soft shoulder exosuits remain underexplored, and face fundamental trade-offs between torque output and dynamic response that are further compounded by the need for multiple actuators to support complex shoulder movement. This work addresses these constraints through a volume-optimized spindle-shaped angled actuator (SSAA) geometry: by reducing actuator volume by 35.7% (357mL vs. 555mL), the SSAA maintains 94.2% of output torque while achieving 35.2% faster dynamic response compared to uniform cylindrical designs. Building on the SSAA, we develop a curved abduction actuator (CAA) based on the SSAA geometry and a horizontal adduction actuator (HAA) based on the pouch motor principle, integrating both into a dual-DOF textile-based shoulder exosuit (390 g). The exosuit delivers multi-modal assistance spanning shoulder abduction, flexion, and horizontal adduction, depending on the actuation. User studies with 10 healthy participants reveal that the exosuit substantially reduces electromyographic (EMG) activity across both shoulder abduction and flexion tasks. For abduction with HAA only, the exosuit achieved up to 59% muscle activity reduction across seven muscles. For flexion, both the single-actuator configuration (HAA only) and the dual-actuator configuration (HAA,+,CAA) reduced EMG activity by up to 63.7% compared to no assistance. However, the incremental benefit of adding the CAA to existing HAA support was limited in healthy users during flexion, with statistically significant additional reductions observed only in pectoralis major. These experimental findings characterize actuator contributions in healthy users and provide design guidance for multi-DOF exosuit systems.

翻译：面向双自由度软肩外骨骼服的便携式气动系统目前仍处于探索不足的阶段，并且在扭矩输出与动态响应之间存在根本性的权衡，而支撑复杂肩部运动需要多个驱动器这一需求进一步加剧了这种权衡。本研究通过一种体积优化的纺锤形倾斜驱动器几何结构来解决这些限制：通过将驱动器体积减少35.7%（357毫升对比555毫升），该纺锤形倾斜驱动器在保持94.2%输出扭矩的同时，与均匀圆柱形设计相比，实现了35.2%更快的动态响应。基于纺锤形倾斜驱动器，我们开发了一种基于其几何结构的弯曲外展驱动器，以及一种基于囊式电机原理的水平内收驱动器，并将两者集成到一个双自由度、基于纺织材料的肩部外骨骼服中（重390克）。该外骨骼服可根据驱动模式，提供跨越肩部外展、屈曲和水平内收的多模式助力。对10名健康参与者进行的用户研究表明，该外骨骼服在肩部外展和屈曲任务中均显著降低了肌电活动。对于仅使用水平内收驱动器的外展任务，外骨骼服在七块肌肉上实现了高达59%的肌肉活动降低。对于屈曲任务，与无助力状态相比，单驱动器配置（仅水平内收驱动器）和双驱动器配置（水平内收驱动器+弯曲外展驱动器）均将肌电活动降低了高达63.7%。然而，在健康用户进行屈曲动作时，在已有的水平内收驱动器支持基础上增加弯曲外展驱动器所带来的增量效益有限，仅在胸大肌上观察到了具有统计学意义的额外降低。这些实验结果表征了驱动器在健康用户中的作用，并为多自由度外骨骼服系统的设计提供了指导。