From Hardware-in-the-Loop to Hybrid Process Simulation: An Ontology for the Implementation Phase of a Manufacturing System

Hardware-in-the-loop (HIL) is a widely used testing approach for embedded systems, where real components and/or controllers are tested in closed-loop with a simulation model. In this paper, we generalize HIL by combining multiple simulations and real components into a Hybrid Process Simulation (HPS). An HPS is a test setup that contains at least one simulated and one actual component, but may contain many of both. It is implemented such that each simulated component can be swapped out with its real counterpart without making changes to the existing system, and vice versa. In this paper, an ontology which provides a conceptual architecture is developed for an HPS, such that a general interpretation of a manufacturing system's implementation is made possible. A formalized application method is then devised for replacing simulations with real processes and vice versa. A conceptual architecture is put forth that separates the effect of a component from its spatial essence (volume or mass). This separation allows workpieces in a manufacturing process, for example, to go from the physical world into the virtual world (computer simulation) and back again repeatedly. The conceptual architecture is applied to a small manufacturing line in the following scenarios: replacing a real robot with a simulated robot, replacing a manufacturing cell with a simulated manufacturing cell, and adding a new simulated manufacturing cell to the existing system. These applications successfully demonstrate how an HPS can be used to test a manufacturing system setup with multiple regions of real and simulated components.