Review of Resistive Force Models for Earthmoving Processes

The force required to insert a tool into a medium is of major interest for the design and automation of earthmoving machinery. The present work reviews previous investigations on forces encountered during earthmoving processes by cyclic (but nonrotary) excavation machines. The objective is to integrate the formulation for cutting and penetrating forces to those for excavation. Common practices for characterizing an unfrozen medium and the associated tool actions are discussed, followed by a general overview of various models describing earthmoving tasks of penetration, cutting, and excavation. Observation and analysis of cutting and excavation models reveals that there is not a common ground for their validation, but it also identifies a core of key parameters, reduced in number and essential to any further excavation model. The paper suggests a normalized experimental verification and comparison of the models before they can be further used.