Numerical and Experimental Studies on 3D Printed Compliant Mechanisms in Gripper Applications

The article describes two versions of a gripper's fingers that utilize compliant revolute kinematic pairs in their operation. The goal in designing the gripper was to create a universal structure that allows for easy adjustment of torsional stiffness and maximum rotation angle as needed. Two compliant revolute joints were proposed and applied in the creation of two versions of the gripper’s fingers. In both joints, one geometric parameter was selected for variation. Finite element analysis was conducted to calculate the statics within the parameter range. Based on the calculations, stiffness charts were created as a function of parameter values. Subsequently, using 3D printing technology in resin, two gripper fingers were produced. Experimental tests were conducted on these fingers to assess their torsional stiffness. The computational and experimental results were compared. The designed fingers are best suited for pneumatic grippers. When using them, complex force control can be eliminated because the gripping force increases gradually in accordance with the compliance of the gripper, rather than abruptly. The fingers also exhibit different stiffness characteristics depending on the direction of the grip - outward or inward.