Two competing linear models for flexible robots: comparison, experimental validation, and refinement

The modeling of a rigid robot attached to a flexible base is addressed in this work. Two approaches are compared: the finite element method (FEM) and the transfer matrix method (TMM). Initially, idealized models of the hydraulic actuators are used that do not include flexible effects in the joints. Those models greatly overestimate the second natural frequency of the system, therefore the identification of local flexibilities in the joints is pursued to improve the results. The very good agreement between both approaches, and their ability to represent the physical system (once joint flexibility is included), confirms their efficiency and relevance in this context.