We investigate how well a physics-based simulator can replicate a real wheel loader performing bucket filling in a pile of soil. The comparison is made using field test time series of the vehicle motion and actuation forces, loaded mass, and total work. The vehicle was modeled as a rigid multibody system with frictional contacts, driveline, and linear actuators. For the soil, we tested discrete element models of different resolutions, with and without multiscale acceleration. The spatio-temporal resolution ranged between 50-400 mm and 2-500 ms, and the computational speed was between 1/10,000 to 5 times faster than real-time. The simulation-to-reality gap was found to be around 10% and exhibited a weak dependence on the level of fidelity, e.g., compatible with real-time simulation. Furthermore, the sensitivity of an optimized force feedback controller under transfer between different simulation domains was investigated. The domain bias was observed to cause a performance reduction of 5% despite the domain gap being about 15%.

翻译：我们研究了基于物理的仿真器在模拟真实轮式装载机进行土堆铲斗填充时的复现精度。通过现场试验时间序列数据，对车辆运动与驱动力、装载质量及总功进行了对比。车辆被建模为包含摩擦接触、传动系统和线性执行器的刚体多体系统；土壤则采用不同分辨率（含/不含多尺度加速）的离散元模型进行测试。时空分辨率范围设定为50-400毫米和2-500毫秒，计算速度介于实时速度的1/10,000到5倍之间。研究发现仿真-现实差距约为10%，且对仿真保真度水平的依赖性较弱（例如兼容实时仿真）。此外，我们探究了优化力反馈控制器在不同仿真域间迁移时的敏感性。尽管域间差距约为15%，但观测到的域偏差仅导致控制器性能下降5%。