Evaluation of Hopping Robot Performance With Novel Foot Pad Design on Natural Terrain for Hopper Development

This letter presents the hopping performance evaluation on three types of terrains and novel foot pad designs for efficient traverse of hopping rovers. Hopping rovers, called Hopper, are expected to explore scientific richness areas where wheeled vehicles are hard to traverse. In order to succeed in the robotic planetary exploration, optimization and efficient designs of rovers are essential. Almost all planetary surfaces are covered with sand, called regolith, which makes hopping efficiency bad. In this letter, we discover the hopping performance on three kinds of terrains. Moreover, we also propose the method of increasing hopping performance on soft soil. Inspired by the conventional wheeled vehicle design, treads, called grouser, are installed on the bottom of the foot pad. While grousers are effective on hard ground and soft soil, they are ineffective on bilayer terrain. Bilayer means that hard ground is covered with thin regolith. And the other novel grouser shape is designed based on the soil interaction model using a multi-objective evolutionary algorithm. The proposed design improves the hopping performance on soft soil in comparison with the straight grouser.