Antenna azimuth position control using Quantitative feedback theory (QFT)

In most of the practical systems there exists some structured parametric uncertainty for which it is difficult to maintain good stability margins and performances for the closed loop system. In conventional control, if plant parameter changes we cannot guarantee about the system performance, hence it is necessary to design robust control for uncertain plant. There are various strategies involved for the antenna azimuth position control such as PID controller, fuzzy logic controller etc. But Quantitative feedback theory (QFT) has proved to be superior as it is not only taken care about the system performance but also the parametric uncertainty exists in the position control system by designing a robust controller. QFT is a frequency domain design technique which allows the trade-off (or quantification) among the simplicity of controller structure, minimization of cost of feedback, existing plant parametric uncertainty and the achievement of desired performance specification at each and every frequency of our interest. In this paper a robust QFT controller and Pre-filter has been designed for the 2-Degree of Freedom (DOF) parametric uncertain azimuth position control system to satisfy both the performance specifications and stability specifications. This work has been accomplished with the help of QFT Toolbox in MATLAB Environment. System response with proposed QFT controller and Pre-filter is shown and commented according to the result.