A pneumatic chamber-actuated modular robotic gripper

With the rapid advancement of industrial automation, higher demands have been placed on the compliance, loading capacity, and grasping adaptability of robotic grippers. Although existing soft grippers exhibit excellent compliance, they generally suffer from weak load-bearing capacity, insufficient stiffness, and uncontrollable deformation under external forces, owing to their reliance on flexible polymers as the primary structural material and the lack of rigid skeletal support. This paper presents a modular flexible robotic gripper actuated by pneumatic chambers. The finger of the proposed gripper consists of an actuation layer and a rotation layer. The actuation layer is fabricated from silicone material with rectangular-cross-section pneumatic chambers, which undergo expansion deformation upon pneumatic actuation. The rotation layer is constructed using high-rigidity material integrated with torsion springs to achieve passive resetting. Based on the Yeoh hyperelastic model and the principle of virtual work, a nonlinear deformation model of the pneumatic chamber is established, revealing the mapping relationship between input air pressure, bending angle, and expansion volume of the chamber. Single-chamber deformation and overall bending simulations of the gripper are conducted using Abaqus finite element software, identifying an optimal chamber wall thickness of 2.0 mm. This parameter achieves a joint bending angle of approximately 30° while balancing structural strength and load capacity. Experimental validations via pneumatic bending tests and grasping experiments demonstrate that the single chamber reaches a bending angle of 27.3° at 80 kPa, and the experimental results are in good agreement with the theoretical model. The gripper can stably grasp various common daily objects. Featuring a compact structure, low cost, and strong reconfigurability, the proposed modular flexible gripper can be adapted to grasp objects of different sizes and shapes by adjusting the number of joints. It effectively balances compliance and grasping stability, providing a novel solution for industrial applications such as fragile object grasping and medium-small workpiece handling.