VIOLATION OF PUBLISHING ETHICS. Robust tracking control for twin rotor multiple-input multiple-output system modelled by uncertain fully-actuated mechanical form with additive disturbances

VIOLATION OF PUBLISHING ETHICSTRMS finds applications across various fields, including aerospace, robotics, education, and research. In control system development field, TRMS provides an excellent platform for developing and testing control algorithms due to its nonlinear and coupled dynamics. This research aims to develop a robust tracking control approach for twin rotor multiple-input multiple-output system (TRMS). First, the model of TRMS is written in the space state of uncertain fully-actuated mechanical form with additive disturbances caused by existence of measurement errors, payload variations, and external disturbances. The robust controller is then designed using the sign function and auxiliary controller to ensure that the closed system including TRMS system and robust controller is always adjusted so that the position-tracking errors tend to the origin, the closed-loop system is globally robust and stable with the lumped system uncertainties caused by modeling errors, the aerodynamic coupling between the vertical and horizontal movements, and friction forces that affect the motions of TRMS. The advantages of this method are a fast transient period, high precision, and strong robustness, and without the adaptive mechanism, it can be applied widely to practical applications such as high nonlinear systems, robotic manipulators, and rigid spacecraft attitude control systems. Finally, to show the advantages this control method is applied to the angles tracking control problem of TRMS which has high nonlinear characteristics, input torque disturbances, and the coupling between the vertical and horizontal movements. The experimental results are presented with the choosing of parameters as nominal parameters that validate the proposed solution. The prominent advantages of this method include a zero percent overshoot, a transient response time of approximately 1s for the yaw angle and 1.5 s for the pitch angle, and superior impulse disturbance rejection compared to linear control. Specifically, the proposed controller stabilizes the pitch angle to its desired initial value within 1s, while the stabilization time for the yaw angle is also 1 s.