Evaluation of virtual controller interface device and software-in-the-loop simulation

In current practice, hardware-in-the-loop simulation and software-in-the-loop simulation are two typical methods for traffic signal control research. The former uses a controller interface device (CID) to connect an actual traffic signal controller to micro-simulation software when conducting a simulation, whereas the latter uses software packages to take the roles of actual signal controllers. Using an actual signal controller can help to generate more reliable simulation results; however, the operational costs of CIDs limit the applicability of hardware-in-the-loop simulations. In this paper, a virtual controller interface device (VCID) is proposed to connect the actual signal controllers to simulation software. The proposed device communicates with the actual signal controller through the US national transportation communications for intelligent transportation systems protocol (NTCIP), which provides great operation flexibility, such as remote control, and reduces the operating costs compared with previous hardware-in-the-loop simulations. The simulation performance of the VCID is compared with software-in-the-loop simulations through a case study in this paper. It is found that the proposed device is able to provide accurate and reliable traffic simulation results: the relative difference with software-in-the-loop simulations is only 1.8%, but it requires significantly less effort and has a lower cost.