Paper presented at the 16th European-African Regional Conference of the ISTVS
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Title: Simulation of change in supporting force when imparting vibration by distinct element method
Authors: Tomohiro Watanabe, Ryoma Higashiyama, Kojiro Iizuka, and Dai Watanabe
Abstract: Robots with leg mechanisms have been investigated for planetary exploration as exploration rovers with outstanding running performance. The legged rovers are efficient in moving on rough terrain because the leg mechanism has a high degree of freedom. However, the surfaces of planets (For example, Mars and the Moon etc.) are not only rough but also loose. Owing to the inherent characteristics of loose ground, legged rovers mostly slip because the motion of their legs deforms the surface of loose ground. To solve this problem, we proposed a walking method for preventing legged rovers from slipping. Our previous study confirmed that the shear strength of the ground and sinkage of the rover legs increased when imparting vibration. In-creasing these parameters cause an increase in the supporting force, which is the resistance force exerted on the legs of the rovers by the ground. The running performance of a legged rover is related to the supporting force. The walking method was proposed based on the effects that vibration changes the ground parameters. The proposed method's ef-fectiveness was shown by an experiment in which a legged testbed walked on loose ground. To improve the running performance of legged rover, the supporting force must be estimated to select a suitable vibra-tion that can efficiently increase the bearing capacity. In this study, we simulated the bearing capacity when imparting vibration to the ground by the discrete element method (DEM). The simulated result was similar to the actual change in the bearing capacity when imparting vibration qualitatively. This relationship offers valuable information for under-standing the mechanism whereby the bearing capacity is increased by imparting vibrations.
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