Water jumping motion extends the robot's movement space and flexibility. However, the jumping performance is influenced by multiple factors such as driving force, rowing trajectory, and robot structure. The interaction force between the robot and water surface is complicated due to water deformation, and the difficulty of the water jumping increases with the robot's scale. This article designs a miniature water jumping robot with rowing driving legs. The hydrodynamic model between driving legs and water is established based on the modified Wagner theory with consideration of water surface deformation. Particularly, the dynamic model of the robot for the whole jumping process is also developed related to multiple factors. Then, the jumping performance is improved by optimizing the energy storage modality, rowing trajectory, and supporting leg shapes through the theoretical analysis and experiments. The fabricated robot weights 91 g, and its length, width, and height are 220, 410, and 95 mm, respectively. The maximum water jumping height and distance are 241 and 965 mm.

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.

Aiming at mimicking the jumping locomotion of water striders, a new continuous jumping robot on water is proposed. Compared with the horizontal rowing motion, the jumping capability of water striders is challengeable to imitate, since the impact force on water is easy to cause the sinking of the robot. In this paper, a jumping mechanism based on springs is designed to produce a large thrust for the robot to jump. The shape of supporting legs and center of gravity of the robot are carefully designed so that the robot can jump on the surface continuously and smoothly. Influences of several critical factors, including the area of supporting legs, spring stiffness and jumping angle, on jump performance are analyzed by means of dynamic simulation and experiments. The fabricated robot weighs about 10.2 g and can continuously jump on water with the maximum leap height and length of 120 mm and 410 mm, respectively.