A study on dynamic behaviors of pilot mining robot according to extremely cohesive soft soil properties

Abstract

KIOST developed a deep-sea mining robot called MineRo to collect manganese nodules in 2007. The MineRo is equipped with two tracks. Furthermore, KIOST also designed and manufactured a pilot mining robot which is named MineRo-II in 2012. MineRo-II is composed of four track modules. This paper is concerned with the dynamic behavior of the MineRo-II on extremely cohesive soft soil. In general, it costs a lot of time and much money for deep-sea test. Therefore, numerical simulation for prediction of dynamic behaviors has to be performed before a deep-sea test. In the numerical simulation, information of mining robot and soil properties are most important to analyze driving performance and dynamic response of MineRo-II. It is possible to get information of MineRo-II from the cad model in the design phase. But it is difficult to get exact soil properties of test sites. A terra-mechanics model of extremely cohesive soft soil is implemented in form of relationships of normal pressure to sinkage, of shear stress to shear displacement. In this paper, Wong model is applied to the terra-mechanics model. This model is necessary to get many soil coefficients for numerical simulation. However, in soil testing, obtained soil property data are limited in number. In this paper, dynamic behaviors of MineRo-II are analyzed according to driving velocity, steering ratio and variable extremely cohesive soft soil properties. Dynamic responses of MineRo-II are turning radius, sinkage and slip ratio. Relationships between dynamic responses and variable soil properties are derived. It will be used to predict dynamic behaviors of MineRo-II through inshore-test. The dynamic analysis program of tracked vehicle is developed using Newmark-β method based on incremental-iterative scheme in FORTRAN. Copyright ？ 2013 by The International Society of Offshore and Polar Engineers (ISOPE).