An Untethered, Jumping Roly-Poly Soft Robot Driven by Combustion

We have developed a fully untethered and combustion-actuated soft robot powered by nitrous oxide-propane/butane gas mixtures. Since the specific energy content of hydrocarbons is significantly higher than that of batteries (comparing energy per weight), our design demonstrates a simple geometry taking advantage of the latest development in soft robotics. This design includes a roly-poly toy geometry enabling equilibration into an upright orientation after each jump event. We were able to show stable operation even on rough terrain. Upon gas ignition, our robot (diameter 18 cm, weight 2.1 kg) jumped and covered distances of 0.5m with a single hop-and-roll movement and an apex of up to 0.2 m. We further calculated the specific energy efficiency of the here-presented design by comparing liberated combustion and resulting potential energy. Analyzing jump pathways, we also identified length and tendency of a jump.