Adaptive sliding mode for path following control of the unmanned helicopter based on disturbance compensation techniques

This paper aims to address the robust control problem of the unmanned helicopter during a path-following task in the presence of inertia uncertainty and external disturbance. A combination of the adaptive sliding mode control method and a nonlinear disturbance observer is proposed as a solution, where the upper bounds of the parametric uncertainty and disturbance are not required in advance. Firstly, according to the force of the flight system, the dynamic model is established by using the Newton-Euler equation and simplified properly. Then an adaptive sliding mode variable structure control method is proposed to combine with adaptive control method, nonlinear disturbance observer (NDO) and sliding mode control techniques which is used to obtain the position controller and attitude controller, respectively. On the premise of sliding mode control to ensure the control robustness, the adaptive control variables are used to compensate the parameter uncertainty and extern disturbance. Base on the Lyapunov theory, the global asymptotic stability is validated. Finally, the algorithm is verified by Matlab simulation experiment and the result is analyzed. It can be seen that the adaptive sliding mode control method has invariance to parameter perturbation and external disturbances and is feasible.