While much work has been done recently in the realm of model-based control of soft robots and soft-rigid hybrids, most works examine robots that have an inherently serial structure. While these systems have been prevalent in the literature, there is an increasing trend toward designing soft-rigid hybrids with intrinsically coupled elasticity between various degrees of freedom. In this work, we seek to address the issues of modeling and controlling such structures, particularly when underactuated. We introduce several simple models for elastic coupling, typical of those seen in these systems. We then propose a controller that compensates for the elasticity, and we prove its stability with Lyapunov methods without relying on the elastic dominance assumption. This controller is applicable to the general class of underactuated soft robots. After evaluating the controller in simulated cases, we then develop a simple hardware platform to evaluate both the models and the controller. Finally, using the hardware, we demonstrate a novel use case for underactuated, elastically coupled systems in "sensorless" force control.

翻译：尽管近期在基于模型的软体机器人及软-刚混合机器人控制领域已取得大量研究成果，但多数研究聚焦于具有固有串联结构的机器人。虽然这类系统在文献中占据主导地位，但将不同自由度间内在弹性耦合特性引入软-刚混合机器人设计正成为趋势。本文旨在解决此类结构（特别是欠驱动情形下）的建模与控制问题。我们提出了几种典型弹性耦合的简化模型，这些模型常见于此类系统中。随后设计了一种补偿弹性效应的控制器，并利用李雅普诺夫方法在不依赖弹性主导假设的前提下证明了其稳定性。该控制器适用于一般类别的欠驱动软体机器人。在仿真验证控制器性能后，我们搭建了简易硬件平台以评估模型与控制器。最后，基于该硬件平台，我们展示了弹性耦合欠驱动系统在"无传感器"力控制中的创新应用场景。