RIGID-DISCRETE COUPLING DYNAMIC ANALYSIS OF ROBOT MONO-PEDAL SYSTEM JUMPING IN SAND

In the process of planetary exploration, it involves the landing and movement of the probe on the earth, as well as the collection, storage and return of some sample materials. Therefore, it is necessary to establish a dynamic model of the motion of the probe robot on the sand, so as to optimize the system configuration. In recent years, the studies on jumping detection machinery have received considerable attentions. In this paper, the discrete element method is used to simulate the particle field deformation. The multibody dynamics method is used to model the mechanical system. Then the coupling dynamics simulation and analysis are carried out for the jumping problem of the robot single foot system on the sand. Based on Prandtl-Reissne theory of classical soil mechanics, starting from the form of pressure stratification and momentum transfer of particle field, a modified Poncelet formula is proposed while the inertia force dynamic resistance term describing particle intrusion resistance is modified. The modified formula adds supplementary items related to rigid body acceleration and intrusion depth, and no new fitting coefficient is added compared with the original formula. By comparing with the results of discrete element simulation, it is shown that the proposed modified Poncelet formula can more accurately calculate the sand and soil invasion resistance of the mechanical foot than the original Poncelet formula. Especially, it shows better convergence when reaching a certain invasion depth. Finally, the influence of different size and shape of the mechanical leg's foot on the jumping effect in sand is analyzed, and the approximate calculation formula of the volume of the conical foot and the cylindrical foot on the jumping effect is presented. The simulation results show that the conical sole will replace the volume of the consolidation zone of the particle field. Furthermore, the influence of particles in the consolidation zone of robot foot on the invasion resistance is discussed. This study will expand the rigid-discrete coupling dynamics theory, and provide technical support for the system design of the new type probe moving on the planetary soil.