Design and Quasi-Static Analysis of a Multidirectional Bending Fiber-Reinforced Soft Pneumatic Actuator

Soft pneumatic actuators (SPAs) have demonstrated significant advantages in unstructured environments due to their geometrically nonlinear deformations characterized by large deflections, high strain, and curvature. However, existing SPA designs predominantly exhibit unidirectional actuation or require mechanical transmissions for multidirectional bending actuation, which restricts their operational flexibility. To solve this limitation, this article proposes a multidirectional bending fiber-reinforced soft pneumatic actuator (MDB-FRSPA), and studies its deformation response characteristics under multiple pneumatic boundary conditions. We establish a response surface model for free-end contact force characterization in the MDB-FRSPA. A moment equilibrium-based quasi-static modeling approach is proposed for investigating the correlation between bending angles and internal pressures across varying pressurization states. Building upon this foundation, an experimental testbed is established for validation analysis. The experimental results demonstrate that the contact force output and deformation response characteristics under varying pressure conditions closely align with both finite element method results and theoretical predictions. Experimental validation confirms enhanced adaptability and operational stability of the three-mode flexible gripper with self-reconfigurability composed of MDB-FRSPA s during complex grasping tasks.