A Multiscale Model of Terrain Dynamics for Real-Time Earthmoving Simulation

Abstract

A multiscale model for real-time simulation of terrain dynamics is explored. To represent the dynamics on different scales the model combines the description of soil as a continuous solid, as distinct particles and as rigid multibodies. The models are dynamically coupled to each other and to the earthmoving equipment. Agitated soil is represented by a hybrid of contacting particles and continuum solid, with the moving equipment and resting soil as geometric boundaries. Each zone of active soil is aggregated into distinct bodies, with the proper mass, momentum and frictional-cohesive properties, which constrain the equipment's multibody dynamics. The particle model parameters are pre-calibrated to the bulk mechanical parameters for a wide range of different soils. The result is a computationally efficient model for earthmoving operations that resolve the motion of the soil, using a fast iterative solver, and provide realistic forces and dynamic for the equipment, using a direct solver for high numerical precision. Numerical simulations of excavation and bulldozing operations are performed to validate model and measure the computational performance. Reference data is produced using coupled discrete element and multibody dynamics simulations at relatively high resolution. The digging resistance and soil displacements with the real-time multiscale model agree with the reference model up to 10-25%, and run more than three orders in magnitude faster.

Efficient Haptic Rendering of Regolith

“…To improve realistic haptic perception, while maintaining computational efficiency, a hybrid model could be considered, with finer-grained particles interacting with the tool with coarser macroparticles or even continuum mechanics used for the rest of the simulation, such as in [28]. Additionally, a more detailed user study could determine characteristics most relevant for realistic perception and study users' perception capabilities in detail.…”

Continuous Control of an Underground Loader Using Deep Reinforcement Learning

“…The simulated environment consisted of an LHD and a narrow underground drift with a muck pile (see Figure 1 and the Supplementary Video Material). The environment was created in Unity [24] by using a physics plugin, AGX Dynamics for Unity [25,26]. The vehicle model consisted of a multibody system with a drivetrain and compliant tires.…”

“…The drift was 9 m wide and 4.5 m tall with a rounded roof. The muck pile was modeled using a multiscale real-time model [26] that combined continuum soil mechanics, discrete elements, and rigid multibody dynamics for realistic dig force and soil displacement.…”