Development of Pneumatic In-Plane Soft and Reinforced Finger Actuators: FE Modeling, Experimental Validation and Gripping Application

Robotic grasping and handling of delicate objects call for soft fingers of the gripper with careful design, avoiding damage while maintaining adequate grasp force. This paper presents such a soft, low-pressure pneumatically driven finger-actuator, outlining its design, FE modeling, numerical simulation, development using hyperelastic elastomers, and characterization for bending and force. The provision of a single pneumatic channel with multi-layered silicone casting containing an inextensible fabric underbelly results in differential strain and, in turn, in-plane bending. The application of semi-circular ring reinforcements along the finger length prevents bulging and enhances structural stability, stiffness, and force capability during contact. The entire assembly is modeled and simulated for free bending and blocked tip condition with frictional contact, validated by extensive experiments on the developed finger. The paper concludes with the simulation study on the gripping force in a two-fingered tip prehensile grasp of a circular object using the designed soft fingers.