Inspired by the vertebrate branch of the animal kingdom, articulated soft robots are robotic systems embedding elastic elements into a classic rigid (skeleton-like) structure. Leveraging on their bodies elasticity, soft robots promise to push their limits far beyond the barriers that affect their rigid counterparts. However, existing control strategies aiming at achieving this goal are either tailored on specific examples, or rely on model cancellations -- thus defeating the purpose of introducing elasticity in the first place. In a series of recent works, we proposed to implement efficient oscillatory motions in robots subject to a potential field, aimed at solving these issues. A main component of this theory are Eigenmanifolds, that we defined as nonlinear continuations of the classic linear eigenspaces. When the soft robot is initialized on one of these manifolds, it evolves autonomously while presenting regular -- and thus practically useful -- evolutions, called normal modes. In addition to that, we proposed a control strategy making modal manifolds attractors for the system, and acting on the total energy of the soft robot to move from a modal evolution to the other. In this way, a large class of autonomous behaviors can be excited, which are direct expression of the embodied intelligence of the soft robot. Despite the fact that the idea behind our work comes from physical intuition and preliminary experimental validations, the formulation that we have provided so far is however rather theoretical, and very much in need of an experimental validation. The aim of this paper is to provide such an experimental validation using as testbed the articulated soft leg. We will introduce a simplified control strategy, and we will test its effectiveness on this system, to implement swing-like oscillations. We plan to extend this validation with a soft quadruped.

翻译：受脊椎动物分支的启发，关节式软体机器人是将弹性元件嵌入经典刚性（骨架状）结构的机器人系统。通过利用身体弹性，软体机器人有望突破刚性机器人的局限性。然而，现有旨在实现这一目标的控制策略要么针对特定示例定制，要么依赖于模型抵消——这反而违背了引入弹性的初衷。在近期一系列工作中，我们提出在机器人受势场作用时实现高效振荡运动，以解决上述问题。该理论的核心是"特征流形"，我们将其定义为经典线性特征空间的非线性延拓。当软体机器人初始化于某一特征流形时，其自主演化将呈现规律且具有实用性的模态运动（称为正常模态）。此外，我们提出一种控制策略，使模态流形成为系统的吸引子，并通过调节软体机器人的总能量实现不同模态演化间的转换。通过这种方式，大量自主行为可被激发，这些行为直接体现了软体机器人的具身智能。尽管我们工作的思想源于物理直觉和初步实验验证，但当前的理论框架仍偏重理论推导，亟需实验验证。本文旨在以关节式软体腿为实验平台进行验证。我们将引入简化控制策略，并在该系统中测试其有效性以实现摆动类振荡。未来计划将验证扩展至软体四足机器人。