Development of a monolithic pneumatic soft actuator for fruit grasping*

In soft grippers, deformable materials are crucial for safety and adaptability. However, materials alone are not enough to ensure a successful grip. Soft grippers are generally designed to exploit precision or power grasp but still show limited versatility in handling objects whose characteristics are widely different. This paper presents a soft gripper with a monolithic pneumatic artificial muscle (M-PAM) design. The monolithic approach prevents failure from delamination while it improves lifetime. Concurrently, adjustable finger distance and a foam interface improve stability during grasping. The resulting structure exerts a maximum force of 1.95N and reaches a bending angle of 78.27 degrees corresponding to a positive pressure of 18 kPa. Furthermore, an optimized geometry increases the contact area and grasping strength. A soft gripper integrating two M-PAMs is demonstrated grasping fruit with dimensions ranging from 0.5 to 65 mm.