A New Micro-Manipulator actuated by Ultra-Sonic Wave for Planetary Surface Exploration

Japanese space agencies are planning SELENE mission series, that will launch an orbiter and a lander mission to the moon in the next decade. One of candidates in SELENE 2 missions is a rover mission. A manipulator has strong possibility to be one of equipments mounted on a rover, though. It is to be a periscope and a sampling tool, and can operate other scientific equipments. In this paper, we discuss a manipulator for our rover system and introduce a developed micro manipulator. It has 5 degrees of freedoms and each joint is driven by a Ultra-Sonic Motor (USM) which needs no electrical power to keep a posture of a manipulator. In general, a manipulator spends almost of working times to maintain to its posture, so that is stopped. However, in that time, each actuator makes a torque by using electrical power and also CPU power. That is huge energy loss in the very severe energy environment like the space, and we need some countermeasure on this problem. We strongly believe that the best solution of this problem is to apply USM to an actuator of a joint to solve this problem. To make a torque on a rotor, it should have a large friction on a interface between a stator and a rotor. It means USM can have a large static friction during an idle state, so that works like a clutch. Furthermore, we don't need any electrical and CPU power to stop a rotation of a joint, and it is very light.