Flexible Driving Mechanism Inspired Water Strider Robot Walking on Water Surface

Abstract

The agile and efficient locomotion of water striders on water surface is attributed to the water repellency ability of their slender legs. The legs are usually treated as rigid beams, neglecting the effect of flexible deformation on its movement. Several studies proved that the stable floating ability of water striders is closely related to the flexible legs. This paper focuses on exploring the flexible driven mechanism between the insect and the surface of water and applied them to design a robot. The spatial deformation and force models of the driving legs are established and analyzed based on the Euler-Bernoulli's beam theory. The influence of flexural rigidity and depth of a driving leg on the rowing speed is studied. Results indicates that a flexible driving leg can effectively increase its critical rowing speed and ensure that it does not penetrate the water surface at a higher speed, thus achieving a bigger driving force. Then a water strider robot capable of walking on water surface is proposed, which possesses ellipse-like spatial trajectories by using a limit pinlinkage. The driving legs are fabricated by different stiffness materials. Finally, the skating experiments of the robots with different stiffness of the driving legs were carried out. The results verified that the maximum rowing frequency of the flexible driving legs and maximum moving speed of the robot are more than 30% higher than those with rigid legs, respectively. Moreover, a similarity analysis of hydrodynamic characteristic constants reveals that the flexible driving robot is more analogous to the biological water striders. INDEX TERMS Flexible driving legs, miniature robot, surface tension, water strider.

Stroke Kinematics Analysis and Hydrodynamic Modeling of a Buoyancy-Supported Water Strider Robot

“…The powers under different stroke methods are shown in Figure 15 which clarifies that the robot adopted a rectangle-like spatial stroke trajectory required more energy during the interaction between the paddles and the water. Calculated by Equation (15), the average powers when the robot performed the ellipse-like spatial stroke trajectory and the rectangle-like spatial stroke trajectory were 6.52 × 10 −3 W and 5.25 × 10 −3 W, respectively. It means that the paddle performing an ellipse-like spatial stroke trajectory can provide more power for the robot at the same rotational speed of the paddle.…”

“…The water strider has many advantages such as highly efficient locomotion, a good stability, quiet movement, and little disturbance to the water surface [8,9]. Owing to the unique advantage the water strider has of walking on the water surface and the potential applications of bionic robots inspired by water striders in many areas such as water quality monitoring, aquatic search, and rescue [10], tremendous efforts have been devoted to the development of water strider robots in recent years [9][10][11][12][13][14][15][16][17][18][19][20].…”

“…Considering that it is relative easy to implement, most of the water strider robots developed imitate the slide movement of the water strider. The first type of water strider robots were designed based on the water surface tension support [9,10,[13][14][15][16]. The studies on these robots primarily focused 2 of 24 on the selection of the proper hydrophobic materials for the stroke legs and supporting legs to imitate the hydrophobic properties of the water strider.…”

“…Figure15. The powers of the robot P when the paddles perform an ellipse-like spatial stroke trajectory and rectangle-like spatial stroke trajectory as a function of the running time t.…”

Experimental and theoretical studies on the dynamic landing of water striders on water

“…2,3 Because of important applications such as monitoring and conservation of water quality, the development of bionic robots and vehicles moving on water becomes a promising topic of research. [4][5][6][7] In an ideal case, a water-walking robot should own the ability against the gravity to keep most of its body out of water in order to well execute specific functions. Meanwhile, it is important to exhibit an ability to recover a non-wetting state if its body partially or totally pierces the water surface.…”