Tracking performance evaluation in presence of hard nonlinearities for oscillatory antenna control

In this paper, closed loop performance of a system with hard nonlinear limitations is analyzed. In order to adequately control such a challenging process, an Internal Model Control strategy has been implemented. The controller has been applied to a real time process described by a radio satellite antenna. The performance of the closed loop has been evaluated by changing the natural frequency and the damping factor of the process transfer function. The experimental results show that the designed IMC controller is robust to changes in the natural frequency between [-5%, +20%] and to changes in the damping factor between [-50%,+100%]. The performance has also been tested for various resolution steps in the actuator (i.e. a stepper motor).