| Robostrider |
| The study of live water striders led us to attempt the construction of a mechanical water strider "Robostrider". The challenge was to build a device capable of self propulsion light enough to be supported by surface tension. At the scale where surface tension is important, the weight of a handmade water strider increases with complexity; therefore it was important to develop a very simple driving mechanism. |
| The first "robostrider" was a simple wire armature shaped roughly like a water strider. It was built to demonstrate that a metal object that is denser than water could be supported by surface tension. If Robostrider 1 hadn't been able to float, the possibility of an actuated version would be out of the question. |
| Robostrider 2 demonstrated the kind of actuation mechanism that would power the final version. The actuator is a thin elastic band coiled around a pulley which is connected to the rowing legs. In order to simplify testing, Robostrider 2 floated on a foam hull instead of thin legs. |
| The final version of robostrider incorporated actuated middle legs and four support legs, modeled after live water striders. It sports aluminum construction with stainless steel legs. In one winding, it was able to travel a full 20 cm in five strides. Below is an animation of Robostrider 3 in action. |
Robostrider 3 in motion