This paper proposes a new mobility system for planetary exploration robot using springs and linear actuators . In microgravity environment, it is difficult to obtain the horizontal velocity, because the friction force between a robot and the ground is very small. By pushing the ground, however, the robot can not only hop, but also obtain the horizontal velocity. The proposed hopping robot consists of two masses, and can push the ground by using springs . The robot can hop from the stationary

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... te by transforming the elastic energy to the kinetic energy using the sprigs and linear actuators. Furthermore the robot can land without bounding by transforming the kinetic energy to the elastic energy. The simulation studies and the ground experiments show the effectiveness of the proposed mobility system.