Two-degree-of-freedom Control Structure for Unstable Processes with Time Delay

The present study suggests the maximum sensitivity of stable plant can be achieved with good robust and performance trade-offs in a reasonable range. However, there is not no fixed structure of controller making the system get the maximum sensitivity of this range for the unstable time-delay process. In this paper, a modified two degree of freedom control scheme adapting a novel filter structure is proposed for the unstable process with time delay. The scheme has deeply analyzed the parameter of controller, using the maximum sensitivity function to evaluate the robustness of system and the integral absolute error to evaluate the output performance. The range of maximum sensitivity function is considered and the compromise of the robustness and performance is realized. Finally, the control simulation example for unstable time-delay process demonstrates the effectiveness of this approach.