The 3D printing robot hand learns to feel

The concept: flexible grippers from the 3D printer use sensors to recognize how firmly they can grip without damaging anything. Technical systems such as robots or other machines should learn to grip "sensitively" in a similar way to a human hand. Future applications include harvesting robots that pick strawberries without crushing them, or autonomous rovers that safely retrieve unknown samples. In publicly funded projects such as "BioGrip", researchers are inspired by nature to solve problems. They try to understand the underlying biological principle, imitate it technologically and develop it further. This approach is known as bionics or biologization.

"Technological advances in additive manufacturing now make it possible to adapt many more biological concepts than before," emphasizes mechatronics engineer Hannes Lauer from the Fraunhofer Institute for Material and Beam Technology IWS, who is supervising the BioGrip project. "Nature is full of solutions. If we as engineers get stuck, it's always worth looking at their concepts." Moritz Greifzu, Group Manager Process Chains and Product Design, adds: "Bioinnovation processes often take several years and currently still require a lot of support and, above all, interdisciplinary collaboration. The aim here is to train a new generation of bionic engineers who have a strong network and experience with complete innovation processes."

Finray effect: Fin encloses object

In this specific case, the project partners are making use of the ability of the fins of certain fish to react to pressure with a counter-movement rather than an evasive one, i.e. to enclose the attacking force. The fish themselves use this to move more easily. The engineers used this effect, known as finray, as part of the BioGrip project from mid-2021 to early 2023. They printed grippers equipped with sensors that can gently grasp objects thanks to Finray technology. To do this, the Fraunhofer IWS first created a gripper base structure - similar to the fin skeleton of fish - from flexible polyurethane. A 3D printer was used, which works according to the additive principle of fused filament fabrication (FFF).