Automatic gain Control for Unity Feedback Control Systems

In this paper, an automatic gain control scheme is first proposed for analyses and designs of unity feedback control systems. The controlled system is a nonlinear feedback control system. The overall system is equivalent to a conventional automatic gain control loop with command tracking error input. Therefore, it gives good command tracking behaviour while keeping robust characteristic of the original AGC loop. Furthermore, it gives good robustness for coping with fast large parameter variations. The stability and effective of controlled systems are verified by time responses, frequency responses, and parameter variation testing with three numerical examples. Comparisons are also made with the PID control. Key-Words: Automatic gain Control, nonlinear feedback System.