Output Feedback Linearization Based Controller for a Helicopter-like Twin Rotor MIMO System

In this paper, an output feedback linearization based controller is designed to stabilize the Twin Rotor Multi-input Multi-output System (TRMS), and make its beam track accurately a reference signal, or reach desired positions in 2 DOF. Only yaw and pitch angles are considered available for measurement. An observer, to estimate the remaining states, is coupled with feedback linearization technique in a two-stage procedure. In the first stage, propellers thrusts are considered as virtual control inputs that lead to a TRMS canonical model for which feedback linearization is applied straightforwardly. In the second stage, the motors torques and actual control input voltages are computed, respectively, by solving algebraic equations and inverting motors models. In the proposed approach, the coupling effects are maintained in controller derivation and so there is no need to decouple the TRMS into horizontal and vertical subsystems, as usually done in the literature. Exponential stability of the closed loop is guaranteed by using the second method of Lyapunov. To show the performance and the effectiveness of the proposed controller, simulation results are presented.