Effects of gravity on rigid rover wheel sinkage and motion resistance assessed using two-dimensional discrete element method

Abstract

Elucidating the effects of gravity on rover/rover wheel performance is important because it can provide a basis for predicting their performance on extraterrestrial surfaces based on test results obtained on Earth. Results of previous studies by Wong (2012) and by Wong and Kobayashi (2012) indicate that if in conducting performance testing of rovers/rover wheels on Earth with identical mass to that on the extraterrestrial surface, instead of with identical normal load (force) used in the current practice, their performance on the extraterrestrial surface can be predicted based on test results obtained on Earth. As described herein, the effects of gravity on rigid rover wheel sinkage and motion resistance were investigated using the two-dimensional discrete element method. The rover wheel mass is unchanged under various gravity conditions. The results of this study substantiate the findings presented in Wong (2012) and Wong and Kobayashi (2012). Given identical mass, the sinkage of a rigid rover wheel under Earth gravity g is the same as that under a different gravity gex: 1/6g–2g. It is also shown that the ratio of the motion resistance of a rigid rover wheel under gravity gex to that under Earth gravity g is equal to the ratio gex/g.