Fy2002 Ground -based Research Announcement for Space Utilization Research Report Study on Mobility Mechanism under Micro-gravity Environment 6. Investigators

(1) Introduction Recently, there are various kinds of tasks to be conducted in space, such as building and operation of the international space station, docking and rendezvous system, inspection and repair of satellite, as well as planetary exploration. In such operations, unmanned robots are most promising tools for future exploration and utilization over the microgravity environment. The mobility system under microgravity is key technology in those fields. So this research focuses on the investigation of the mobility mechanism in micro-gravity environment. To study mobility system under low gravity environment such as on the surface of small bodies, a method to use friction with the surface is discussed and investigated. As an effective locomotion, hopping is considered in this research. The model of hopping mechanism and dynamics is designed and analyzed. The effectiveness of the hopping mechanism is evaluated by micro-gravity drop-tests and numerical simulations. Attitude control scheme and landing mechanism are also studied for hopping robots. The influence of the friction and the level of the gravity on such performance of hopping robot as the hop angle, hop speed, rotation etc. is also investigated through micro-gravity experiments. (2) Research Results For detailed understanding of mobility system under micro-gravity environment, the numerical model of hopping mechanism was built and analyzed by some computer simulations. Some robots with hopping mechanism were developed as shown in Fig.1. The effectiveness of hopping mechanism was confirmed by micro-gravity drop tests as shown in Fig.2. The new hopping robot with landing function was developed, which consists of three masses connected with the spring and the linear actuator. Fig.3 shows the landing