Modeling of the supporting legs for designing biomimetic water strider robots

Recent studies on the insect water strider showed that the insect heavily relies on surface tension force to stay afloat. Inspired by this insect, water strider robots have been developed using the same locomotive principles as the insect. This paper focuses on numerically modeling the supporting legs of the insect and the robots. The rigid-leg model as well as the compliant-leg model is developed using numerical approaches, under an assumption made on the water surface breaking condition. The effect of different leg material and geometry are discussed. It is shown through simulations that four 7 cm-long Teflonreg coated compliant supporting legs with optimized shapes can lift up to 4.3 grams (0.15 g/cm), while an actual prototype carried 3.7 grams. Another prototype using twelve of these legs successfully lifted 9.3 grams. Experiments show that the analyses capture the important features of the supporting legs. The design rules proposed in this paper are useful in understanding the insect statics and also the robotic water strider supporting leg design. This study allows a heavier robot to be used for education, entertainment or environment monitoring purposes