Fixed-Structure $${H_{\infty}}$$H∞ Controller Design for Two-Rotor Aerodynamical System (TRAS)

This paper illustrates an efficient controller design technique for the control of a laboratory setup, known as two-rotor aerodynamical system (TRAS). A decentralized control of TRAS using control scheme known as fixed-structure $${H_{\infty}}$$H∞ control is presented in this paper. TRAS is a multi-input–multi-output system having strong coupling between horizontal and vertical planes. The main focus of this paper is to design a reduced-order, robust controller for TRAS with a fixed structure. First, the nonlinear model is linearized and then system is decoupled into horizontal and vertical planes. Two independent SISO controllers are designed for both planes using proposed control approach. Comparison is made between conventional $${H_{\infty}}$$H∞ and fixed-structure $${H_{\infty}}$$H∞ controller design techniques under the influence of different command inputs. The performance of controllers under the effect of external disturbance is also taken into account to show the effectiveness of the proposed approach. In spite of having reduced order, the proposed approach has shown significant improvement toward tracking performance and disturbance rejection as compared to conventional $${H_{\infty}}$$H∞ approach.