Robust Control Techniques for State Tracking in the Presence of Variable Time Delays

In this paper, a distributed driver-in-the-Ioop and hardware-in-the-Ioop simulator is described with a driver on a motion simulator at the U.S. Army TARDEC Ground Vehicle Simulation Laboratory GVSL. Realistic power system response is achieved by linking the driver in the GVSL with a full-sized hybrid electric power system located 2,450 miles away at the TARDEC Power and Energy Systems Integration Laboratory PE SIL, which is developed and maintained by Science Applications International Corporation SAIC. The goal is to close the loop between the GVSL and PE SIL over the Internet to provide a realistic driving experience in addition to realistic power system results. In order to preserve a valid and safe hardware-in-the-Ioop experiment, the states of the GVSL must track the states of the PE SIL. In a distributed control system utilizing the open Internet, the communications channel is a primary source of uncertainty and delay that can degrade the overall system performance and stability. The presence of a cross-country network delay and the unavoidable differences between the PE SIL hardware and GVSL model will cause the GVSL states and PE SIL states to diverge without any additional action. Thus, two robust strategies for state convergence are developed and presented in this paper. The first strategy is a non-linear Sliding Mode control scheme. The second strategy is an H-infinity control scheme. Both schemes are implemented in simulation, and both schemes show promising results for state convergence in the presence of variable cross-country time delays.