A simplified dynamic model for front-end loader design

Abstract

The front-end loader is an indispensable machine for the off-road construction equipment industry. It is a classic example of a working machine with complex interactions between its subsystems (hydraulic, mechanical, and electrical). Dynamic models of the full-scale vehicle coupled with event-based operator models are currently used to help quantify the overall system performance, efficiency, and operability. However, these models are complex and not always necessary to characterize the response of individual subsystems. There is great value added to the design process — especially in prototyping of new vehicle platforms — in development of simpler models that can quickly and accurately define first-order measures of system loads and performance. This paper presents a subscale dynamic model, which isolates the boom and bucket manipulator systems of the front-end loader for the purpose of design load characterization. The model includes state equations governing the hydraulic dynamics across the control valves and in the cylinders, as well as soil—tool interaction loads (passive earth loads) at the bucket cutting edge. The governing equations of motion for the multi-rigid body model of the bucket linkage are developed using Kane's method. The proposed model is intended to accelerate the structural design and analysis of the boom and bucket linkage subsystems and may yield useful information for optimization purposes. The output from the dynamic simulation is compared with the field test data of the machine.