Design of Three-wheeled Planetary Rover Tri-StarII

Abstract

Many studies have been made concerning the planetary Rover, the essential element in the planet exploration mission, and some have already been put into practical use in exploration missions. In this paper, we propose an expandable three-wheeled rover, Tri-StarII, as a planetary rover having a new mechanism. Tri-StarII has three drive wheels and does not need suspension mechanism, so the drive mechanism is simplified and lightened. By use of this feature, the body is designed to be an expandable type with the wheels attached to a slide arm. By folding it up in the lander carrying it to the surfaces of the moon or Mars, and expanding to large size when running, it can achieve running stability equivalent to larger rovers. The wheels are attached to the body with an offset wheel steering mechanism. For the expansion and steering mechanisms, latches having very small actuators are used and the increase in weight is minimized by introduction of these mechanisms. Further, the running wheel uses a spring wheel usable in space environments. By using the expansion mechanism for the spring wheel, the energy loss in running is decreased and performance is improved. We confirmed the feasibility of an experimental unit.