Development of a Simplified Load-Cycle Model for Wheel Loader Design

Abstract

An indispensable part of the off-road construction equipment industry, the front-end-loader (FEL) is a classic example of a working machine, having complex—often nonlinear—interaction between its hydraulic, mechanical, and electrical subsystems [1]. Current state-of-the-art in dynamic simulation of these machines employs full-scale vehicle models and an event-based operator model to quantify the overall system performance, efficiency, and operability. Quantifying these machine parameters is further complicated by the variability in the machine's working environment and task profile. It is recognized that full-scale simulations may offer the most insight into the machine performance and system efficiency; however, even simplified models can yield useful information for structural design, rapid prototyping, and local optimization. This paper explores developing a sub-scale dynamic model for the boom and bucket manipulator system on a FEL that will adequately characterize the system response for the purposes of design and optimization. The equations of motion for the multi- rigid body model of the manipulator system are derived using Kane's method. State equations governing the hydraulic flow to the cylinders and reaction forces on the bucket are employed to model the manipulator system's interaction with the machine and work-pile, respectively. Output from the dynamic simulation is correlated and compared to data gathered during field test operation of the machine.