Data Link Antenna Control System Design Using A Fuzzy Controller
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1. Introduction
The performance of stabilization and tracking system mainly depends on the servo control system that driving the antenna pedestal. However, the outdoor antenna servo system is subject to significant torque disturbances from wind pressures and gusts on the antenna structures, as well as bearing and aerodynamic frictions. This control system should provide a sharp directivity in spite of the environmental disturbances and internal uncertainties.


Stabilization Algorithm
An antenna system mounted on a vehicle, having disturbance motion, becomes unstable owing to vehicle's roll, pitch and yaw motion. If this antenna system was used for data page link between moving vehicles, the disturbance bring to pointing error and disable to communicate between moving vehicles


The Structure of Antenna System
Generally, antenna system is composed of three parts, ACU(Antenna Control Unit), PCU(Pedestal Control Unit), SAP (Stabilized Antenna Pedestal). ACU controls SAP by transferring control command for azimuth and elevation angles of SAP and calculate position of the moving vehicle. In figure 1, general structure of antenna system was represented. SAP is mechanical part that directly controls the azimuth and elevation angle of the antenna for pointing a moving vehicle. PCU controls SAP using azimuth and elevation angle value form ACU.

Simulations

The fuzzy-PID controller for data page link tracking antenna system was design and the performance was verified with computer simulations. Matlab and Simulink were used for these simulations. A Fuzzy rule based controller was designed and the performance was tested with several environmental conditions. In figure 7, Simulation block diagram of Matlab and Simulink was shown. For the availability test for the designed fuzzy-PID controller, the comparison with conventional PID controller was performed