Design of Synergetic Controller based on Nonlinear State Observer for Twin Rotor MIMO System

Abstract

This paper presents the design of a robust controller for the Twin Rotor MIMO System (TRMS) by integrating Synergetic Control Theory (SCT) with a Nonlinear State Observer (NSO). TRMS is a benchmark system widely used to evaluate advanced control algorithms due to its highly nonlinear dynamics, strong coupling, parameter uncertainties, and susceptibility to external disturbances. Conventional controllers often struggle to ensure both stability and precise trajectory tracking under such conditions. To overcome these challenges, the proposed method leverages SCT to guarantee convergence of pitch and yaw angles to desired trajectories while preserving system stability in the presence of unknown disturbances. Since synergetic control laws require full state information, a nonlinear state observer is developed to estimate unmeasured states with high accuracy. The stability of both the controller and observer is rigorously proven using Lyapunov functions. Simulation results demonstrate that the combined SCT–NSO approach effectively eliminates disturbances, achieves fast convergence, and ensures accurate trajectory tracking, outperforming traditional methods. The proposed framework provides a promising solution for robust control of complex nonlinear systems such as TRMS and paves the way for further extensions to terminal synergetic control designs.