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：我们提出了一种受章鱼触手启发的多段缆索驱动软体机械臂及其新型建模方法。该模块化操作臂的每个段由柔性管状骨架、软体硅胶臂体以及两个刚性端盖构成——端盖用于连接相邻段并解耦不同段的驱动缆索。软体机械臂采用铸造工艺制造，刚性端盖通过3D打印制成，实现了低成本且便捷的加工。由于在追求更高柔顺性时取消了中间刚性缆索导向结构，缆索对软体硅胶臂体产生的非线性挤压效应被纳入考量。为此我们建立了解析静力学模型，以描述弯曲曲率与缆索长度之间的关系。实验表明，该模型相比基线模型展现出更优的预测性能，特别是在大弯曲条件下。基于该非线性静力学模型，我们进一步构建了多段臂的运动学模型，并据此推导出运动规划算法。实验结果显示，所提出的软体臂具有高灵活性和大工作空间，且基于本建模方法推导的算法相比基线模型算法，跟踪误差降低了最高52%。该建模方法预计可广泛应用于各类软体缆索驱动执行器与操作臂。