Tip-over Prevention for Lunar and Planetary Lander with Translation-rotation Motion Conversion Mechanism

Abstract

The landing system which is adaptable to different kind of terrain condition is required to achieve touchdown on rough and inclined terrains. However, it is difficult to design a landing system which is applicable to a wide variety of terrains. In the conventional landing gear system, aluminium honeycomb crush and oil damper are used to mitigate landing impact. These classical mechanisms have advantages of simplicity and large shock absorption capability. However, those classical passive landing gears are ill suited for landing to the uneven and inclined areas and for landing with lateral velocity. To prevent from lander tip-over, it is necessary to make landing gear adaptable to wide condition of terrain. In order to solve this problem, we propose a new mechanism for safety landing on an inclination. In general, tipping-over of spacecraft is caused by the torque which is generated by the difference of the force acting on each leg. However, it is difficult to synchronize force acting on the all the landing legs. Here, we focused on the difference of the force acting on each leg. In case of touchdown on the inclination, the force acting on the upper leg is larger than any other legs. In case of touchdown with a lateral velocity, the force acting on the former leg is larger than any other legs. Therefore, if we can convert this force to torque which is acting to the direction against to the rotating of the spacecraft, it becomes possible to prevent tip-over of the spacecraft.