Two-degree-of-freedom internal model controller for NCS

To aim at the network delays in the industrial control process and uncertain object model, we add a feedback filter into the feedback loop of the traditional internal model controller, which we call it two-degree-of-freedom internal model controller for the networked control system, so that we can adjust the track and the robustness respectively. The results of the simulation show the validity of the control scheme, and indicate the system has better dynamic performance and robustness.