Force-balancing algorithm to remove the discontinuity in soil force during wheel loader excavation

An important issue in developing a virtual simulation environment for a wheel loader is capturing the interaction force between the bucket and soil during excavation. In this work, we review several important studies on fundamental earthmoving equations (FEE) and confirm that discontinuity of soil force occurs when soil is loaded with a large terrain angle using a soil model based on traditional FEE for a wheel loader. This discontinuity is removed by recalculating the external friction angle to satisfy the force equilibrium condition under the assumption that the combined net normal and frictional force is zero in a certain condition. Comparison of an actual test with an inverse dynamic simulation using measured data confirms that the soil model proposed in this study is sufficient for estimating the external force transferred to the structure during actual operation. This soil force model can be used for durability and performance assessments in the initial design of wheel loaders.