Estimation of Supporting Force for Lunar/Planetary Exploration Rovers with Function of a Push-Pull Locomotion

This paper proposes a supporting force model of a Push-Pull Locomotion on the rough terrain. Planetary rovers should avoid many obstacles on the planetary surfaces, for instance, rocks, stones, and rough terrain. When planetary rovers become stuck, this typed rover can move by using a large supporting force of the wheel, which is generated by keeping a position of a supporting wheels relative to the ground and move to another position. Recently, planetary rovers need to be controlled autonomously, therefore, the interaction mechanics between supporting wheels and soil need to be investigated. The drawbar pull force of the rotational wheel model has been investigated in the terramechanics field, however, in the Push-Pull Locomotion, the supporting wheels are locked during bulldozing soil. Therefore, the conventional model cannot apply to the supporting wheels. As the initial step, this paper constructs the supporting force model of the locked wheels without considering normal force of a wheel by using the Coulomb and GLEM (Generalized Limit Equilibrium Method) theory. The validity of these models is confirmed by a single wheel bulldozing tests. The experimental results revealed that the proposed model based on the GLEM theory can predict the supporting force of the wheel without a normal force in each wheel size and sinkage.