1 Neurobionics Lab, Rehabilitation Institute of Chicago , Chicago, Illinois.
2 Department of Biomedical Engineering, Northwestern University , Evanston, Illinois.
Soft Robot. 2018 Apr;5(2):138-148. doi: 10.1089/soro.2017.0004. Epub 2018 Mar 2.
Substantial device mass and control complexity can hinder the impact of wearable robotic technologies, such as exoskeletons. Thus, despite promising previous research, the development of a simple, lightweight actuator for these systems has not yet been fully realized. The purpose of this study was to derive and demonstrate a proof-of-concept for a pneumatic interference actuator (PIA)-a lightweight, soft actuator able to produce torque by the self-intersection of a fabric balloon that arises from changes in physical geometry. General closed-form equations are derived to express the expected actuator torque and mechanical work as functions of the balloon geometry, pressure, and deflection angle. Hard and soft cylindrical physical prototypes were constructed to assess the accuracy of the mathematical models. The proposed mathematical model was found to agree with the pressure-volume relationship and successfully predict the maximum torque as a function of geometry, pressure, and deflection at nonzero deflection angles. Peak powers up to 122.1 ± 10.0 W (mean ± standard deviation), with a resting internal pressure of 158.0 ± 0.2 kPa, were observed from the hard actuator prototype. For the soft actuator prototype, peak powers of 97.9 ± 21.1 W were observed at a resting pressure of 166.8 kPa. The work performed was within 3.2% ± 3.4% and 14.4% ± 8.2% of theoretical values across all trials, and within 19.1% ± 4.4% of theoretical values when compared to the torque-angle relationship. This study highlights the promise of utilizing the self-intersection of a PIA to perform human-scale mechanical work, and future research will focus on implementations for wearable robotic systems.
大量的设备质量和控制复杂性可能会阻碍可穿戴机器人技术（如外骨骼）的影响。因此，尽管之前有很有前景的研究，但为这些系统开发一种简单、轻便的执行器尚未完全实现。本研究的目的是推导和证明气动干扰执行器（PIA）的概念验证，这是一种能够通过织物气球的自相交产生扭矩的轻量级软执行器，这种自相交是由物理几何形状的变化引起的。推导出一般的封闭形式方程，将预期的执行器扭矩和机械功表示为气球几何形状、压力和偏转角的函数。构建了硬和软圆柱形物理原型，以评估数学模型的准确性。发现所提出的数学模型与压力-体积关系一致，并成功地预测了作为几何形状、压力和非零偏转角函数的最大扭矩。从硬执行器原型中观察到高达 122.1 ± 10.0 W（平均值 ± 标准差）的峰值功率，内部静止压力为 158.0 ± 0.2 kPa。对于软执行器原型，在静止压力为 166.8 kPa 时观察到 97.9 ± 21.1 W 的峰值功率。在所有试验中，执行的功在理论值的 3.2%±3.4%和 14.4%±8.2%之间，与扭矩-角度关系相比，在理论值的 19.1%±4.4%之间。本研究强调了利用 PIA 的自相交来执行人体规模机械功的潜力，未来的研究将集中在可穿戴机器人系统的实现上。
