Parallel Helix Actuators for Soft Robotic Applications.
Parallel Helix Actuators for Soft Robotic Applications.
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DOI：
10.3389/frobt.2020.00119
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发表时间：
2020
影响因子：
3.4
通讯作者：
Valdastri P
中科院分区：
文献类型：
--
作者：
Chandler JH;Chauhan M;Garbin N;Obstein KL;Valdastri P
软气动弯曲执行器的制造通常涉及多个步骤，以适应复杂内部几何形状的形成以及软材料和不可扩展材料之间的对齐和粘合。当应用于多腔室和小规模（~10毫米直径）设计时，这些过程的复杂性会加剧，导致重复性差。设计通常依赖于组合多个预制的单腔执行器，或者限于简单的（固定截面）内腔几何形状，这可能导致过度膨胀和弯曲效率降低，迫使添加约束材料。在这项工作中，我们通过提出一种使用具有螺旋特征的平行芯的单一材料成型技术来解决现有的限制。我们证明，通过这些内部结构的特定取向和对准，可以在单一材料中制造具有复杂内部几何形状的小直径致动器，而无需额外的设计关键步骤。螺旋设计产生的壁廓限制了径向膨胀，同时通过腔室联锁实现紧凑的设计，简化了脱模。我们提出并评估了具有不同螺旋特征的三腔设计，展示了可观的弯曲角度（>180°），三维工作空间覆盖范围和三倍重量承载能力。通过对常曲率假设的应用和验证，提出了执行器的正运动学模型，并对其进行了校正，以考虑腔室特定的弯曲特性，结果表明，模型尖端平均误差为4.1 mm。这种简单而廉价的制造技术有可能在尺寸和腔室数量上进行缩放，从而允许针对特定应用的软、高移动性执行器的设计，特别是在外科手术或运动应用中。
Fabrication of soft pneumatic bending actuators typically involves multiple steps to accommodate the formation of complex internal geometry and the alignment and bonding between soft and inextensible materials. The complexity of these processes intensifies when applied to multi-chamber and small-scale (~10 mm diameter) designs, resulting in poor repeatability. Designs regularly rely on combining multiple prefabricated single chamber actuators or are limited to simple (fixed cross-section) internal chamber geometry, which can result in excessive ballooning and reduced bending efficiency, compelling the addition of constraining materials. In this work, we address existing limitations by presenting a single material molding technique that uses parallel cores with helical features. We demonstrate that through specific orientation and alignment of these internal structures, small diameter actuators may be fabricated with complex internal geometry in a single material—without- additional design-critical steps. The helix design produces wall profiles that restrict radial expansion while allowing compact designs through chamber interlocking, and simplified demolding. We present and evaluate three-chambered designs with varied helical features, demonstrating appreciable bending angles (>180°), three-dimensional workspace coverage, and three-times bodyweight carrying capability. Through application and validation of the constant curvature assumption, forward kinematic models are presented for the actuator and calibrated to account for chamber-specific bending characteristics, resulting in a mean model tip error of 4.1 mm. This simple and inexpensive fabrication technique has potential to be scaled in size and chamber numbers, allowing for application-specific designs for soft, high-mobility actuators especially for surgical, or locomotion applications.