Effects of Compliance on Path-Tracking Performance of a Miniature Robot

Path-tracking is often challenging in miniature robots because their feet or wheels tend to slip due to the low robot weight. In this work, we investigate the effect of c-leg compliance on path-tracking performance and the obstacle-climbing capabilities of our foldable and miniature robot with soft, c-shaped legs. With its 82 mm x 60 mm x 29 mm size and 29.25 grams weight, a single module of our robot is one of the smallest untethered miniature robots. Our results show that utilizing soft c-shaped legs provides smooth path-tracking performance, similar to a wheeled differential drive robot. However, modules with rigid c-shaped legs are affected significantly by the impact and slip between the leg and the ground, and they perform rather unpredictably. Additionally, modules with wheels cannot climb obstacles 1 mm or larger. We show that using soft legs enhances the obstacle climbing skills of modules by climbing a 9 mm obstacle, while the module with rigid legs can only climb a 7 mm obstacle. These path-tracking abilities and obstacle-climbing capacity support our vision to build a reconfigurable robot using these modules.