Prescribed-time adaptive constraint control of an uncertain nonlinear 2-DOF helicopter

This paper addresses the problem of attitude tracking for a 2-Degree of Freedom (DOF) helicopter system with uncertainties. Euler-Lagrange equations are utilized to develop a nonlinear model for the helicopter, considering the control input constant coefficients and system parameters as unknown. The prescribed-time control approach is proposed using adaptive backstepping to track the desired pitch and yaw positions separately. In Addition, a constrained function is also used to avoid the risk of a larger signal when time gets closer to the appointed settling time. Through the application of the theory of Lyapunov stability, it is shown that the proposed strategy ensures that all closed-loop signals are bounded, and all the states converge within the prescribed time. A significant advantage of this approach is the ability to pre-specify the upper bound of the settling time. Finally, the efficacy and control capabilities of the proposed scheme are verified by obtaining the simulation results on the Quanser 2-DOF helicopter.