HARDWARE-IN-THE-LOOP SIMULATION

Cost effective procedures are needed for evaluating state of the practice traffic signal control equipment so that informed deployment and design decisions can be made. These procedures can also be used by researchers to develop new control algorithms for applications such as transit priority or adaptive control. In order to achieve these objectives, this paper reviews the need and theory of using hardware-in-the-loop simulation procedures. Hardware-in-the-loop simulation presents a new set of challenges for traffic engineering model developers since the correctness of a real-time model depends upon both the numerical computation and the timeliness with which the simulation model interacts with external control equipment. This paper reviews the state of practice, summarizes the fundamental technologies necessary for implementing such a system, and uses a simple statistical test for assessing the real-time errors introduced into a simulation model. This paper can provide a reference for the application of hardware-in-the-loop simulation so that developers can produce procedures that permit rigorous and systematic evaluation of alternative control algorithms using a common microscopic traffic model