Traction Performance Evaluation and Influence Analysis of Planetary Rover Based on Equivalent Friction Coefficient

With the complexity of planetary patrol exploration missions, terramechanics is evolving from a semi-empirical model to a physical model, and the next generation of terramechanics models for planetary rovers requires a physics-based traction performance evaluation index. In response to the wheel slip-sinkage of planetary rover, the equivalent friction coefficient, which presents the influence of sinkage on the wheel-soil friction coefficient, has been proposed to evaluate the traction performance. The single wheel test was implemented, and the wheel equivalent friction coefficient increasing and then decreasing with the slip ratio. The variation trend of equivalent friction coefficient shows that the increase of wheel’s traction force is at the cost of the increase of the sinkage. When the slip ratio exceeds the optimum value, the traction increment provided by the unit sinkage will be reduced, and the risk of vehicle sinkage will increase. Considering the effect of load on wheel traction performance, the relationship between longitudinal slip volume stiffness and load is established using a binary linear equation. The validity of the equivalent friction coefficient was verified on planetary soil simulant, gravel, and slate terrain. The test results showed that the equivalent friction coefficient can be quantitatively evaluated for wheel traction performance under different wheel configurations, motions, and terrain conditions. The equivalent friction coefficient can provide reference for the drive control and risk warning of the planetary rover. © 2024 Chinese Mechanical Engineering Society. All rights reserved.