Soft pneumatic actuators (SPAs) are customizable and conformable devices that enable desired motions in soft robots. Interactions with the environment or handling during their fabrication could introduce defects into SPAs that affect their performance. These defects could lead to high-stress concentrations in the SPA body and heterogeneous, unrepeatable, or inconsistent expansion affecting their reliability. In this work, we aim to improve the reliability of soft robots by modeling and characterizing the performance of SPAs with widely used chamber shapes and cross-sectional geometries under variable loading conditions. We also compare their capacity to provide homogeneous, repeatable, and time-wise consistent expansion with low-stress concentrations and provide a set of principles for the design of reliable SPAs. Expansion of SPAs with Straight chambers demonstrated to be more repeatable, with an average deviation of 0.06 mm and showed more than a thousand times less stress than any other chamber types. The expansion of preshaped SPAs with helical chambers showed to be up to 500% more homogeneous and 300% more efficient than their deflected counterparts. SPAs with squared cross-sectional geometries displayed more than 1000 times more time-wise consistent expansion over their circular counterparts. We conclude that SPAs that retain less potential energy or are less affected by its effects are more reliable. We derive these results into a set of principles for the design of reliable SPAs. These principles offer solutions to make informed decisions before fabrication to mitigate the most common reliability problems for SPAs and soft robots.

中文翻译：

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偏转与预成型软气动执行器：可靠软机器人的设计和性能分析

软气动执行器 (SPA) 是可定制且符合要求的设备，可在软机器人中实现所需的运动。在制造过程中与环境或处理的相互作用可能会在 SPA 中引入影响其性能的缺陷。这些缺陷可能导致 SPA 主体中的高应力集中，以及影响其可靠性的异质、不可重复或不一致的膨胀。在这项工作中，我们旨在通过对具有广泛使用的腔室形状和横截面几何形状的 SPA 在可变负载条件下的性能进行建模和表征来提高软机器人的可靠性。我们还比较了它们在低应力集中提供均匀、可重复和时间一致的扩展的能力，并为设计可靠的 SPA 提供了一套原则。使用直室扩展 SPA 被证明具有更高的可重复性，平均偏差为 0.06 毫米，并且显示的应力比任何其他类型的室都小一千多倍。具有螺旋室的预成型 SPA 的膨胀显示出比其偏转对应物的均匀性高 500%，效率高 300%。具有平方横截面几何形状的 SPA 显示出比其圆形对应物多 1000 倍的时间一致性扩展。我们得出结论，保留较少势能或受其影响较小的 SPA 更可靠。我们将这些结果推导出为一组设计可靠 SPA 的原则。这些原则提供了在制造前做出明智决策的解决方案，以减轻 SPA 和软机器人最常见的可靠性问题。