Modeling and control of a two DOF helicopter using a robust control design based on DK iteration

An alternative way to control a nonlinear system, such as a two Degree Of Freedom helicopter, is the linearization of the model around an equilibrium point, in this case, an equilibrium point around the Pitch angle. Subsequently, the design a Robust Controller for this system is done, using a the DK iteration method. However, when a variation of an angle such as its uncertainty is modeled, the performance of the controller is affected and it might turn itself into an unstable system even when minimal perturbations are presented. In this paper, a nonlinear mathematical model of a two Degree of Freedom helicopter is used. This model is linearized around one specific equilibrium point. Consequently, the uncertainties of the systems are modeled, and finally, the Robust controller by the DK iteration is designed and simulated.