Experimental method for the planar landing of a three-legged asteroid probe: The effects of asymmetric configuration and element forces

Focused on an asteroid probe with three-legged cushioning, this paper discusses the effects of the asymmetric configuration and the element forces form of the planarized cushioning mechanism on the method for developing the landing experiment. The main objectives are to present an accurate experimental analysis of the planar landing and to facilitate the construction of a micro-gravity experimental platform through the theoretical analysis in advance. Probe models based on the planar symmetric and asymmetric configurations of the cushioning mechanism were constructed and their parametric characterization was determined. Mathematical models of the element forces on cushioning legs were established and differences between each set of corresponding element forces were analyzed. Then, dynamics models explaining the landing process were established. On this basis, the maximum initial safe attitude angle and the change process of the attitude variables were researched. The results revealed that the asymmetric configuration greatly reduced the safety margin of the attitude angle and it was determined by the M-R(I) landing as 23°. In addition, the simplified version of the ground friction force could be employed for developing the experiment at the initial attitude angle of 20°, but it affected the results at the initial attitude angles of 0°, 5°, and 10°. At the initial attitude angle of 20°, which is more significant as the critical condition for dangerous landing, the normal footpad-ground contact of the merged leg could adopt the same stiffness coefficient as that of the real leg to facilitate the experimental design without affecting the experimental results.