Bending pneumatic artificial muscles (BPAMs) are particularly promising candidates in the area of soft robotics. Most existing BPAMs that are capable of bending in a two-dimensional plane seem to be hardly suitable for the complexity and diversity of environments. In this paper, we design a BPAM with multi-degree of freedom (multi-DOF), which can bend in three-dimensional space and extend its soft body. And a static analytical model for bending in free space is proposed to give insights into the bending deformation of the BPAM. The bending angle predicted by the developed static model matches well with the corresponding experimental and numerical results, demonstrating the validity of the modeling method for the multi-DOF BPAM. We further validate that the developed model can reliably estimate the bending angle of the BPAM with different geometric parameters. Therefore, the developed static model can be employed as an effective tool for the guidance of the BPAM designs. In addition, a flexible and versatile gripper is fabricated by utilizing the BPAM, which shows an outstanding performance in grasping fragile, irregular, and deformable objects. Experimental results indicate that the maximum grasping mass is about 400 g when the operating pressure is 120 kPa. The developed multi-DOF BPAM also provides enormous potential for future applications that require motion and manipulation in three-dimensional space.

弯曲气动人工肌肉 (BPAM) 是软机器人领域特别有前途的候选者。大多数能够在二维平面上弯曲的现有 BPAMs 似乎很难适应环境的复杂性和多样性。在本文中，我们设计了一种具有多自由度（multi-DOF）的 BPAM，它可以在三维空间中弯曲并扩展其软体。并提出了自由空间弯曲的静态分析模型，以深入了解 BPAM 的弯曲变形。开发的静态模型预测的弯曲角度与相应的实验和数值结果匹配良好，证明了多自由度 BPAM 建模方法的有效性。我们进一步验证了开发的模型可以可靠地估计具有不同几何参数的 BPAM 的弯曲角度。因此，开发的静态模型可以作为指导 BPAM 设计的有效工具。此外，利用BPAM制造了一种灵活且多功能的抓手，在抓取易碎、不规则和可变形物体方面表现出优异的性能。实验结果表明，当操作压力为120 kPa时，最大抓取质量约为400 g。开发的多自由度 BPAM 还为需要在三维空间中进行运动和操纵的未来应用提供了巨大的潜力。利用BPAM制造了一种灵活多用途的抓手，在抓取易碎、不规则和可变形物体方面表现出优异的性能。实验结果表明，当操作压力为120 kPa时，最大抓取质量约为400 g。开发的多自由度 BPAM 还为需要在三维空间中进行运动和操纵的未来应用提供了巨大的潜力。利用BPAM制造了一种灵活多用途的抓手，在抓取易碎、不规则和可变形物体方面表现出优异的性能。实验结果表明，当操作压力为120 kPa时，最大抓取质量约为400 g。开发的多自由度 BPAM 还为需要在三维空间中进行运动和操纵的未来应用提供了巨大的潜力。