The amazing ability of water striders on water surface has attracted many scholars. Especially the flexible driving mechanism enable the driving legs conform to the deformation of the water surface, which effectively improving water striders’ floating ability and stability. However, the current research on water striders has never designed a flexible driven robot prototype like water striders. This paper proposes a new water strider robot that can walk on water surface based on flexible driving mechanism. The robot’s driving legs are designed with flexible materials and possess ellipse-like spatial trajectories like water striders through a limit pin-linkage mechanism. Based on microelement cantilever method, the flexible driving effect was analyzed with different elastic modulus and diameter. It shows that the flexible legs can row at a higher frequency before puncturing the water surface and achieve bigger work in one period compared with the rigid one. At last, the skating experiment of the robot under different stiffness and rowing frequency was carried out. The results verified that the limit frequency of the flexible driving legs and maximum moving speed of the robot are about 41.3% and 36.2% higher than those with rigid legs, respectively. Moreover, a similarity analysis of hydrodynamic characteristic constants reveals that the locomotion of the flexible driving robot is more analogous to the biological water striders than the rigid one.

In the paper, a concept of novel self-reconfigurable robotic system made of the autonomous robotic modules has been reviewed. Each robotic module is made of simple structure and few degrees of freedom; however, a group of the modules is able to change its connective configuration by changing their local connections and has functionality of robotic system which is capable of generating complicated motions and accomplishing a large variety of tasks, such as: transportation, exploration, inspection, construction and in-situ resource utilization. Multimode locomotion and self-reconfiguration are the basic and essential abilities for the self-reconfigurable robotic system. Based on this concept, a new self-reconfiguration system, UBot robotic system that combines the advantages from the chain-based and lattice-based robots has been proposed. Each UBot module which is cubic structure based on universal joint has two rotational DOF and four connecting surfaces that can connect to or disconnect from adjacent modules. The smart structure and the reliable connecting mechanism of the modules make the robot flexible enough to complete multimode locomotion and self-reconfiguration. This paper demonstrates the design philosophy of the UBot module and a solution for multimode motions and self-reconfiguration using the UBot system. The system can complete motion in the modes of quadruped, chain and loop configuration. Besides, the system can deform from one mode to the other though self-reconfiguration. All the proposed methods have been verified though simulations and real hardware experiments.