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多大程度上能够复现真实轮式装载机在土堆中进行铲斗装载的过程。对比基于现场测试的时间序列数据，包括车辆运动与驱动力、装载质量及总功。车辆被建模为带有摩擦接触、传动系统和线性驱动器的刚体多体系统。对于土壤，我们测试了不同分辨率的离散元模型，并采用了多尺度加速技术。时空分辨率范围在50-400毫米和2-500毫秒之间，计算速度介于实时速度的1/10,000至5倍之间。仿真与现实差距约为10%，且对模型保真度水平的依赖较弱（例如，兼容实时仿真）。此外，研究了优化力反馈控制器在不同仿真域间转移时的敏感性。尽管域间差距约为15%，但观察到的域偏差导致性能下降5%。