Principles of control for robotic excavation

Excavation can be considered one of the most unstructured problems in the construction environment. On one hand, many technologies have been developed in the past to build shelters using earth. On the other hand, the combinations of encountered soil characteristics are almost infinite and may vary significantly within the range of one meter. Rocks, boulders, and electric cables are buried in the ground, endangering the lifes of human operators and disabling excavation equipment. Efforts to optimize the energy used per volume of excavated soil is generally a futile undertaking. Although early lunar excavators will not have to worry about electric cables in the ground, the desire to robotize this operation, while also minimizing the consumption of energy, provides a challenging task to researchers familiar with the problem of cutting soil. Although control models exist to handle the dynamic relationship between a robot and its environment, the modeling of soil tool interaction is very difficult. This paper will first present an approach to understanding the principles of path and motion control, which is based on scaled modeling and experimentation with different soil types and soil conditions. Second, it will discuss the effect of explosive loosening on the amount of force and energy needed to excavate along a given path. This analysis will be based on experimental research using lunar simulant.