A study on the alignment angle of the lugs for the lunar rover’s crawler mechanism and its mobility performance

Currently, the environment for human habitation on the Moon and technologies for mining lunar resources are being actively researched. Space rovers are necessary for this purpose. On a planet like the Moon, the ground is soft and covered with sand. When a spacecraft travels on such terrain, it is prone to the “stuck phenomenon,” in which the wheels spin around and the vehicle becomes unable to travel. There is a need for an explorer that is less prone to getting stuck; in other words, one with high traveling performance. However, the conditions for improving mobility performance are not clearly defined. They depend on the shape and physical properties of the terrain. To pursue the conditions that enhance traveling performance, this study first focused on “lug”, one of the key conditions that improve travel performance. Lugs have the function of pushing out sand to generate a reaction force. This improves traveling performance. Commonly, lugs are installed perpendicular to the wheels and crawlers. Therefore, we examined the relationship between mobility performance and the alignment angle of the lugs. In this study, we conducted running experiments on crawlers with different lug attachment angles. The crawlers were single-wheeled and were assumed to run in a straight line. To evaluate the running performance of each crawler, we used the slip ratio. We investigated the adequate lug’s alignment condition for each crawler’s running performance. We discussed the results from the perspective of machining studies on how the lugs enter and exit the sand. We also employed PIV (Particle Image Velocimetry) analysis to investigate the effect of the lugs on the sand during operation.