Fractional order control of dissimilar redundant actuating system used in large air craft

The paper proposed a strategy to address the issue of dynamical force fighting and to provide precise tracking of actuator control surface driven by two dissimilar actuators. To solve this issue, a fractional order control strategy is adopted and its performance is compared with conventional PID controller. The control strategy includes the design of two fractional order PID controllers in position feedback configuration. In order to keep the actuator dynamics at similar pursuit, a third fractional order PID controller is added in such a way as to feed force compensation signal in position feedback loop of both actuators. To optimally tune the controller parameters, Nelder-Mead optimization technique is employed based on specified performance criteria. The objective function is defined by assigning weights to each time domain and frequency domain performance parameters. To check the robustness of proposed scheme, an external disturbance is applied at the control input of both actuators. Simulation results illustrated that proposed controller is able to reduce the force fighting problem as well as precisely track commanded input as compared to PID controller.