| Hoang Duc Long Synthesis of Terminal Synergetic Controller Based on Nonlinear State Observer for 2-DOF Helicopter System |
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| Abstract. This paper presents the synthesis of a robust control scheme for a Two De-gree-of-Freedom Helicopter System based on Terminal Synergetic Control combined with a Nonlinear State Observer. The 2DOFHS is a highly nonlin-ear, strongly coupled MIMO system characterized by parametric uncertain-ties and unknown external disturbances, which makes control design particu-larly challenging. To address these issues, a terminal synergetic control strat-egy is developed to ensure finite-time convergence of the pitch and yaw an-gles to their desired reference values, while guaranteeing closed-loop stabil-ity in the presence of bounded disturbances. Since the terminal synergetic control law requires full state information, a nonlinear state observer is de-signed to estimate the unmeasured state variables, namely the angular veloci-ties of the pitch and yaw motions. The observer is constructed to achieve fast and accurate state estimation, enabling effective implementation of the pro-posed control law without direct measurement of all system states. Lyapun-ov-based stability analysis is carried out to rigorously prove finite-time con-vergence of the tracking errors and asymptotic convergence of the observer estimation errors. The effectiveness and robustness of the proposed control-ler–observer structure are validated through comprehensive simulation stud-ies under different operating conditions, including set-point regulation and trajectory tracking scenarios, as well as in the presence of bounded external disturbances. The simulation results demonstrate fast transient response, high tracking accuracy, and strong disturbance rejection capability, confirming the superiority of the proposed approach for controlling nonlinear helicopter systems. |
| Keywords: 2-DOF Helicopter System, Terminal Synergetic Control, Nonlinear State Ob-server, Lyapunov function |
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| DOI: https://doi.org/10.54381/itta2026.4.03 |