Modeling and Identification of Soil-tool Interaction in Automated Excavation

Abstract

In the process of automating an earthmoving machine, we have developed a model of soil-tool interaction that predicts resistive forces experienced at the tool during digging. The predicted forces can be used to model the closed loop behavior of a controller that servoes the joints of the excavator so as to fill the bucket. In this paper, we extend the state of the art in two ways. First, we present a reformulated version of the classical fundamental equation of earthmoving often used to model soil-tool interaction. The new model includes consideration of previously unaccounted phenomena in the interaction of an excavator bucket as it moves through soil. Secondly, given that soil properties can vary even within a work site, we present an online method to estimate soil parameters from measured force data. Finally, we show how the predicted resistive force is used to estimate bucket trajectories.