Although robots are increasingly found in a wide range of applications, their use in proximity to humans is still fraught with challenges, primarily due to safety concerns. Roboticists have been seeking to address this situation in recent years through the use of soft robots. Unfortunately, identifying appropriate models for the complete analysis and investigation of soft robots for design and control purposes can be problematic. This paper seeks to address this challenge by proposing two complementary modeling techniques for a particular type of soft robotic actuator known as a Fiber-Reinforced Elastomeric Enclosure (FREE). We propose that researchers can leverage multiple models to fill gaps in the understanding of the behavior of soft robots. We present and evaluate both a dynamic, lumped-parameter model and a finite element model to extend understanding of the practicability of FREEs in soft robotic applications. The results of experimental simulations using a lumped-parameter model show that at low pressures FREE winding angle and radius change no more than $$2\%$$ . This observation provided confidence that a linearized, dynamic, lumped-mass model could be successfully used for FREE controller development. Results with the lumped-parameter model demonstrate that it predicts the actual rotational motion of a FREE with at most $$4\%$$ error when a closed-loop controller is embedded in the system. Additionally, finite element analysis was used to study FREE design parameters as well as the workspace achieved with a module comprised of multiple FREEs. Our finite element results indicate that variations in the material properties of the elastic enclosure of a FREE are more significant than variations in fiber properties (primarily because the fibers are essentially inextensible in comparison to the elastic enclosure). Our finite element analysis confirms the results obtained by previous researchers for the impact of variations in winding angle on FREE rotation, and we extend these results to include an analysis of the effect of winding angle on FREE force and moment generation. Finally, finite element results show that a $$30^{\circ }$$ difference in winding angle dramatically alters the shape of the workspace generated by four FREEs assembled into a module. Concludingly, comments are made about the relative advantages and limitations of lumped-parameter and finite element models of FREEs and FREE modules in providing useful insights into their behavior.

中文翻译：

---

纤维增强软执行器的两种互补建模方法的评估

尽管机器人的应用范围越来越广，但它们在人类附近的使用仍然充满挑战，主要是出于安全考虑。近年来，机器人专家一直在寻求通过使用软机器人来解决这种情况。不幸的是，为设计和控制目的而为软机器人的完整分析和调查确定合适的模型可能是有问题的。本文旨在通过为一种称为纤维增强弹性外壳 (FREE) 的特定类型的软机器人致动器提出两种互补的建模技术来应对这一挑战。我们建议研究人员可以利用多种模型来填补对软机器人行为理解的空白。我们提出并评估一个动态的，集总参数模型和有限元模型，以扩展对 FREE 在软机器人应用中的实用性的理解。使用集中参数模型的实验模拟结果表明，在低压下，自由缠绕角和半径变化不超过 $$2\%$$。这一观察结果为线性化、动态、集中质量模型可以成功地用于免费控制器开发提供了信心。集总参数模型的结果表明，当闭环控制器嵌入系统时，它可以预测 FREE 的实际旋转运动，误差最多为 $$4\%$$。此外，有限元分析用于研究 FREE 设计参数以及由多个 FREE 组成的模块实现的工作空间。我们的有限元结果表明，FREE 的弹性外壳材料特性的变化比纤维特性的变化更显着（主要是因为与弹性外壳相比，纤维本质上是不可拉伸的）。我们的有限元分析证实了先前研究人员获得的关于缠绕角变化对自由旋转的影响的结果，我们将这些结果扩展到包括分析缠绕角对自由力和力矩产生的影响。最后，有限元结果表明，$$30^{\circ }$$ 的缠绕角差异极大地改变了由四个 FREE 组装成一个模块所产生的工作空间的形状。最后，