Effect of Soil Type on Running Performance of Small Lunar Rover

It is very easy for a small lunar rover to slip on the regolith of the lunar surface and become stuck. Previous studies have quantitatively evaluated the effects of wheel geometry, such as elliptical or eccentric wheels, on the performance of a rover when climbing up slopes. These studies reported that the rovers were able to run on a 30-degree slope made of silica sand. In this study, a small rover was designed and created, and running tests were conducted using lunar soil simulant and silica sand to predict its performance on the lunar surface. The effects of soil differences on the performance of the rover were clarified through the running tests and the measurement of reaction force on the lug. Although the rover exhibited a greater slip ratio on the lunar soil simulant than on the silica sand, the rover with eccentric wheels was able to climb up to a 30-degree angle on the lunar soil simulant. The results for the sinkage measurement of the rover showed that the eccentric wheels prevented sinkage with their up-and-down motion, enabling the rover to climb steep slopes. Furthermore, the tests for measuring the reaction force on the lug indicated that the density change in the lunar soil simulant did not provide sufficient reaction force, and that the running performance on the lunar soil simulant was lower than that on the silica sand.