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.

Connected dominating set (CDS) has been used widely in mobile ad hoc networks by numerous routing, broadcast, and time synchronization protocols. Although computing minimum CDS is known to be NP-hard, many distributed protocols have been proposed to construct a small CDS. However, these protocols are either too complicated, need non-local information, are not adaptive to topology changes, or fail to consider the difference in energy consumption for nodes within and outside the CDS. In this paper, we present two timer-based energy-aware connected dominating set protocols. Our protocols extend the MAC-layer timer-based connected dominating set protocol (MTCDS) so that the energy level at each node is taken into account when constructing the CDS. Simulation results have shown that our protocols effectively construct an energy-aware CDS with a very competitive size and prolong the network operation under different levels of nodal mobility.