Design of a 3D-printed polymeric compliant constant-force buffering gripping mechanism

This paper reports on a novel 3D-printed polymeric compliant constant-force buffering gripping mechanism. The motivation of this work is to develop a buffering gripping mechanism to avoid the damage of manipulated biological object induced by excessive displacement output. The presented zero-stiffness mechanism is realized by connecting the negative-stiffness part and positive-stiffness part in parallel. The negative stiffness is obtained by a bistable buckled fixed-guided beam mechanism. Analytical modeling and simulation study are carried out before the prototype fabrication with 3D printing. Experimental results show that the proposed gripping mechanism can provide a constant output force of 780 mN in 500 μm motion range. Results also reveal that the manipulated object bears no deformation in the constant-force range, which is enabled as the excessive displacement output is buffered by the mechanism. The proposed design can be used to replace the existing combined force-displacement control strategy for fragile object manipulation.