We propose a novel multi-section cable-driven soft robotic arm inspired by octopus tentacles along with a new modeling approach. Each section of the modular manipulator is made of a soft tubing backbone, a soft silicon arm body, and two rigid endcaps, which connect adjacent sections and decouple the actuation cables of different sections. The soft robotic arm is made with casting after the rigid endcaps are 3D-printed, achieving low-cost and convenient fabrication. To capture the nonlinear effect of cables pushing into the soft silicon arm body, which results from the absence of intermediate rigid cable guides for higher compliance, an analytical static model is developed to capture the relationship between the bending curvature and the cable lengths. The proposed model shows superior prediction performance in experiments over that of a baseline model, especially under large bending conditions. Based on the nonlinear static model, a kinematic model of a multi-section arm is further developed and used to derive a motion planning algorithm. Experiments show that the proposed soft arm has high flexibility and a large workspace, and the tracking errors under the algorithm based on the proposed modeling approach are up to 52$\%$ smaller than those with the algorithm derived from the baseline model. The presented modeling approach is expected to be applicable to a broad range of soft cable-driven actuators and manipulators.

翻译：我们受章鱼触手启发提出了一种新型多段缆索驱动软体机械臂及其建模方法。该模块化机械臂的每个分段由软管骨架、软硅胶臂体及两个刚性端盖构成，其中端盖用于连接相邻分段并解耦不同分段的驱动缆索。通过3D打印刚性端盖并进行浇铸成型，实现了低成本且便捷的制造工艺。针对因取消中间刚性缆索导向结构以提高柔顺性而导致的缆索压入软硅胶臂体的非线性效应，本文建立了解析静力模型以表征弯曲曲率与缆索长度之间的关系。实验表明，相较于基线模型，所提模型在预测性能上展现出显著优势——尤其在大弯曲工况下表现更为突出。基于该非线性静力模型，进一步建立了多段机械臂的运动学模型并推导出运动规划算法。实验结果表明，所提出的软体机械臂具有高灵活性和大工作空间，基于本文建模方法的算法跟踪误差相比基线模型算法最高降低52%。所提出的建模方法预期可广泛应用于各类软体缆索驱动执行器与机械臂系统。