Comparison of Gradeability of a Wheel-Legged Rover in Wheeled Mode and Wheel-Legged Mode

The gradeability of a rover is important for the detection in Mars exploration mission. The traditional rovers used in former American Mars projects and Chinese Chang'e project are all wheeled rover. The gradeability of this type rover is limited by the wheel-soil interaction. The wheel-legged rover has stronger gradeability than wheeled rover because it can use more soil strength. This paper proposes the structure of a wheel-legged rover utilizing the rocker-bogie suspension, the kinematics principle and terrametrics principle of the rover. In wheel-legged mode, the traction force provided by the brake wheel is more than 1.5 times of the drawbar pull of a same size driving wheel. This paper compares the gradeability of mobile system in the wheeled mode and the wheel-legged mode when the rover climbs 20 degrees slope, compares the maximum power of mobile system when rover climbs 20 degrees slope in different modes, and predicts the maximum power of rover in climbing 25 degrees slope utilizing wheellegged mode.