Adaptive Improved Terminal Sliding Mode Tracking Control for 2-DOF Helicopter with Uncertain Parameters and Unknown Input Constraints

This paper studies the attitude tracking problem for 2-DOF helicopter system. An adaptive improved terminal sliding mode controller is proposed to address parameter uncertainties and unknown input constraints simultaneously. Specifically, an adaptive law is designed in the controller to eliminate the effects from uncertain parameters. In addition, the controller integrates terminal sliding mode and Nussbaum gain to counteract the impact of unknown input constraints. Finally, the effectiveness of the controller is substantiated through Lyapunov theory, and favorable tracking results are demonstrated by simulations.