This paper presents a scale model excavator intended to allow for studies on human-machine interactions. In the past, this work has been performed on full-scale equipment which can be dangerous and costly to acquire and operate, or fully in simulation, which requires high precision models of complex effects such as soil forces (e.g. using the Discrete Element Method, DEM, simulating thousands of particles). Also simulation models with scenes projected on computer monitors or in virtual reality may not be realistic enough for the human operator to be fully immersed and behave in a realistic manner. The motion of the small-scale excavator presented here is directed by a digital model of a hydraulic machine given inputs of operator commands and actuator forces, allowing it to mimic the behavior of various hydraulic architectures (e.g. pressure compensated load sensing vs open center vs closed center systems). The excavator is used to dig in physical soils, generating realistic soil-tool interaction forces (which are fed back into the digital machine model) without the need for computationally expensive DEM models. This allows for rapid, low-cost evaluation of various hardware modifications as well as human-machine interaction effects. We also present some preliminary data from a pilot study investigating energy efficiency.

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