Anthropomorphic robot hand using the principle of sweat and fingerprints of human hands

In our daily life, when a small amount of sweat or water forms on a person's hand, we can empirically feel that the friction force of the hand increases, and the objects are gripped well. However, if sweat or water forms heavily, we can feel the friction decrease when holding an object. In this study, we analyzed the degree to which fingerprints and sweat present on a person's hand can affect the friction force between the hand and the gripping object. We fabricated an anthropomorphic robot hand with a fingerprint structure to set up an environment similar to that of the human hand, and performed object-holding and friction-change experiments by changing the amount of sweat to verify that this phenomenon can be applied to a robot hand. Furthermore, we for the first time proposed and developed a variable friction system using fluids and microstructures to solve the difficulty of anthropomorphic robot hand force control. By applying the manufactured variable friction system and performing an active friction control performance test and an object grip test of the robot hand, we validated that the fingerprint and sweat of a human hand can affect the grip of an actual object.