A 3D Physics-Based Hydraulic Excavator Simulator

The actuation of hydraulic excavators is a complex and not intuitive task which requires long and costly training periods, since the qualification of the operator has a significant impact in productivity and safety. Simulation-based training combined with virtual reality is becoming a competitive alternative to traditional training to reduce costs and risks in the instruction of excavator operators. Several excavator training simulators have been developed, but none of them features a dynamic model of the machine complete enough to simulate all the maneuvers performed in the daily work of real excavators. The authors have applied real-time simulation techniques from multibody system dynamics to develop a full 3D physics-based excavator simulator made up of 14 rigid bodies with 17 degrees of freedom. The simulation engine includes a custom collision detection algorithm and detailed tire force and contact force models. Terrain excavation and bucket loading and unloading are also simulated. The resulting model delivers realistic real-time behavior and can simulate common events in real excavators: slipping on slope terrains, stabilizing the machine with the blade or the outriggers, using the arm for support or impulsion to avoid obstacles, etc. The simulator console has a semi-immersive virtual reality interface that emulates the excavator cabin. The operator console imitates most of the controls of the real machine cabin using low-cost standard USB input devices: steering wheel, 2 joystiks with the standard excavator functions and 2 pedals. A tactile screen replicates the digital control panel of the excavator, which lets the operator control different machine settings. A hard shell hemispherical dome of 2 m diameter is used to project the subjective view from the operator’s position. The resulting simulator, which can run in a standard PC due to its high computational efficiency, can reproduce almost all the maneuvers performed by real excavators.