I. INTRODUCTION
Soft robots can interact with environments and humans in simplified, safer, and adaptive ways owing to their body compliance [1]. However, they usually cannot generate large forces also due to body compliance, thus unable to realize fast motion. Although some soft robots can realize rapid motions [2]–[6], they require an intensive power input. But intensive power inputs may not be always possible due to limited capability of actuators such as motors, compressors, and especially artificial muscles, or sometimes due to limited power supply, especially when a robot is untethered. To address this problem, in this work, we leverage the internal energy stored in a soft robot to realize strong and fast motion without an intensive power input and strong actuators.