A soft pneumatic bistable reinforced actuator bioinspired by Venus Flytrap with enhanced grasping capability

Soft actuators, as an important part of soft robotics, have attracted significant attention due to their inherent compliance, flexibility and safety. However, low capacity in force and load limits their applications. Prestored elastic energy can improve the capacity in output force and load of soft actuators. This work introduces a soft pneumatic bistable reinforced actuator inspired by the Venus Flytrap's bistable mechanism that allows for the storage of elastic energy. The proposed actuator consists of two separated 3D-printed actuation chambers that are attached to a central prestressed steel shell to achieve bistability. The pressure triggering the pneumatic bistable reinforced actuator from one stable state to the other is derived and validated by experiments. Further experimental comparisons between the proposed actuator and a dual chamber actuator show that the proposed design significantly improves the block tip force, load capacity and stiffness. The pneumatic bistable reinforced actuator also demonstrates superior performance in the actuation speed and bending angle under the same input pressure. Finally, a two-finger gripper is developed using the proposed actuator, which is demonstrated to grasp and hold various objects.